How much does an extension cost per m2: How Much Does a House Extension Cost?

How Much Does a House Extension Cost?

How much does a house extension cost? We get asked this question a lot, so, we thought it worthy of its own post!

It’s not an easy question to answer and obviously depends on a number of factors (etc, etc…), but that’s not the answer you’re looking for is it? You’re really looking for a very rough figure, a general guideline, a starting point.  OK, I’ll try my best.


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Let’s start with a basic single storey extension

say 4m x 5m


Figures have been updated in 2022 following recent price increases in constructions costs of approximately 30%, according to a survey of architects and designers on Design for Me.

You may have heard that the rule of thumb is £1,000-£1,200 per m2. However, this figure is now somewhat out of date. From experience, £2000 per m2 is a now a more realistic estimate for a basic / mid-range house extension. In London and some parts of the South East, these figures could be between £2,300-2,800 per m2. See our separate post on house extension costs in London and the South East here.


So, for your 4 x 5m extension, the build cost would be roughly £40,000.

  • Add on 10-15% for professional fees (architect, planning application, building regs, structural engineer) (£6,000  at 15%)
  • VAT (£8,000)

Single storey house extension cost = £54,000+


How about a double storey extension, same footprint?

As a rule of thumb you can add 50% extra to the build cost of a single storey extension.

So, £40,000 +50% = £60,000 for the basic build cost

  • Add on 10-15% for professional fees (architect, planning application, building regs, structural engineer) (£9,000 at 15%)
  • VAT (£12,000)

Double storey house extension cost = £81,000+


The above figures would apply to a typical, uncomplicated extension in most parts of the UK. However, you should consider that these figures would creep up if any of the following apply:


Does it include a kitchen or bathroom?

  • Add £5,000 for a bathroom. Costs may be more depending on your sanitary ware and finishes.
  • Add £10,000 for a kitchen (again, completely depends on your specification, £10,000 should get you a lower-mid range kitchen with appliances)


Finishes and fittings

Above costs assume modest finishes, fittings, electrics and lighting. Think simple painted walls, carpet floors or possibly engineered oak.

  • If you’re wanting higher-end finishes e.g. tile finishes, fitted joinery etc the costs will increase.
  • Glazing will increase the cost also. Sliding or folding doors are a popular addition to extensions at the moment.


Are there any complex site constraints?

Your builder will need to include additional costs in their quotation if any of the following apply:

  • Your soil type and ground conditions may present more costly construction methods / techniques.
  • Limited access to the site. Will it be easy for the builder to bring in tools and machinery easily?
  • Existing structure. Are you removing any structural walls? If so there will likely be additional costs for steelwork.
  • Are you moving any pipework, drainage, gas meters?



  • As already mentioned above, in the South East you can expect to pay more than the rest of the UK, and notably more in London.


Materials and construction techniques

  • Consider the type/ quality of construction materials involved and the type of construction.


Managing or reducing your project costs

1. It pays to get professional advice from a good architect. They can help you realise the main ambitions for your extension, whilst helping control your costs. They will work with you to make sure you get the most out of your budget to recommend where your budget is best spent, and where costs would be unnecessary or could be minimised.

2. Make sure you get 3-5 quotes from recommended builders (your architect can help compile a tender list for you) to get a firm idea of the costs before starting work.

Your architect can also help you with your building contract, to prevent any nasty surprises down the line. They can also inspect the builder’s work to ensure it’s being carried out in accordance with the agreed design and specifications.

3. Shop around. Designers and contractors are often able to to access trade discounts.



Finding the right architect

Choosing the right architect for your home project is a critical first step, but can also be a bit of a minefield. This is exactly why I set up this website in the first place!

As well as being founder of, I am also a qualified architect. I found that many homeowners search online to find well established or high-end practices (it makes sense – these companies have bigger marketing budgets with stylish websites). However, such practices are often too busy, too expensive and, in fact, often less experienced in dealing with small residential projects on ‘normal’ budgets.

So I wanted to create this platform for those design professionals I know who are suitable, experienced and eager to take on domestic projects like yours. They are often small, young practices or freelancers. The problem was that, before Design for Me, they were very difficult to find! All you need to do is tell us a bit about your project…


Emily  Design for Me

Find your perfect design pro within minutes…

Here at Design for Me we match you with the right design professional, from thousands all over the UK. Get quotes & arrange up to three no obligation consultations. And it’s all completely free! Find out more here or get started below…



filed under Cost Planning, Extensions.

How Much Does a House Extension Cost? 2022 Savings Guide

Planning a house extension is a big job that can seem daunting, especially with so many things to think about.

There are so many decisions to make before you even start building your extension, and so many rules and regulations to follow. That’s why it’s a good idea to get a proper handle on extension costs before you dive in.

In this guide, we’ll discuss:

  • How much an extension costs
  • What affects the cost of building an extension
  • How to save money on an extension
  • What’s involved in fitting an extension
  • How to find and hire a builder

If you want to extend your home and add to your living space, but aren’t quite sure where to begin, keep reading to find out everything you need to know.


How Much Does an Extension Cost?

Extension costs vary widely depending on factors such as the size and how you intend to use it. Smaller, less complex extensions tend to be the most affordable.

Here are some common extension types and their associated costs, from budget to mid-range and to luxury, as well as the time required to complete them:

Extension Type Budget (per sqm) Mid-range (per sqm) Luxury (per sqm) Time Required
Single-storey Extension £1,000 to £1,600 £1,700 to £2,000 £2,200 to £4,000 and up 8 to 10 weeks
Two-storey Extension £1,200 to £1,900 £2,000 to £2,200 £2,300 to £4,000 and up 12 to 16 weeks
Side Return Extension £1,500 to £1,900 £1,900 to £2,200 £2,200 to £2,500 10 to 12 weeks
Glass Extension £1,350 to £1,950 £1,800 to £2,300 £3,000 and up 10 to 12 weeks
Flat Pack Extension £750 to £1,440 £1,275 to £1,800 £1,650 to £3,600 1 to 2 weeks

For a single-storey extension, you can expect it to cost between £1,000 to £1,600 at the lower end of the price range, £1,700 to £2,000 for the mid-range and £2,200 to £4,000 and up at the luxury end of the price range. You can expect this build to be relatively straightforward and box-shaped as a single-storey.

A two-storey extension is estimated to cost £1,200 to £1,900 at the lower end of the price range, £2,000 to £2,200 for a mid-range extension and £2,300 to £4,000 and up for a luxury two-storey extension. A two-storey extension isn’t likely to cost that much more than a single-storey as you’ll only be adding extra joists and walls.

A budget side-return extension is estimated to cost £1,500 to £1,900, £1,900 to £2,200 for a mid-range extension and £2,200 to £2,500 for a luxury side-return extension.

A budget glass extension is likely to cost £1,350 to £1,950, with a mid-range glass extension costing £1,800 to £2,300 and a luxury range to cost £3,000 and up.

When it comes to flat pack extensions, a budget one is likely to cost £750 to £1,440, a mid-range is estimated to cost £1,275 to £1,800 and a luxury flat pack extension is estimated to cost between £1,650 to £3,600.

Please note that the estimates given above are for building the shell of the extension only. The estimates do not include the cost of any fittings and fixtures, since these are entirely of your own choosing.

However, our estimates do include VAT. This is because the vast majority of builders who undertake extensions are VAT registered.

Otherwise, they would only be able to complete one or two projects per year before hitting the government’s VAT registration threshold.

On average, a 30 square metre single-storey extension built on a budget costs between £30,000 to £48,000. If your finances can stretch a bit more, a mid-range extension of this size usually costs between £51,000 and £60,000. These prices exclude fitting costs.

If you want to build a two-storey extension, the costs per square metre aren’t significantly higher. Builders usually quote by the square metre, not on the number of storeys.

Both single-storey and two-storey extensions require foundations and a roof, so the main additional costs you’ll need to consider are scaffolding, extra material for the floor joists and walls, heating, plumbing, and electrics, as well as whatever fittings you choose.

On average, a 40 square metre two-storey extension can cost anywhere from £48,000 to £76,000 if you’re working on a budget or between £80,000 and £88,000 if your budget is more flexible.

A two-storey extension measuring 60 square metres typically costs in the range of £72,000 to £114,000 for a budget project or £120,000 to £132,000 for a mid-range build.

Where you live plays an important factor, too. If you live anywhere near London, it’s likely your extension will cost more.

The cost of a glass extension per square metre come in at around £1,350 to £1,950 per square metre for a budget finish; mid-range will be around £1,800 to £2,300, and a luxury spec will be in excess of £3,000 per square metre.

For a typical extension, budget for around 10 to 12 weeks of labour.

A flat pack extension is a cost-effective route, with prices for a budget option starting at £750 to £1,140 per square metre, mid-range £1,275 to £1,800, and luxury at £1,650 to £3,600. As you’d imagine from the name, the time to build is a lot shorter, too, at just 1 to 2 weeks.

Things get a bit more complicated when you start thinking about kitchen and bathroom extensions.

Planning permission needs to account for plumbing, and then the plumbing actually needs to be installed. To ensure your extension is safe and stands the test of time, it’s a good idea to get this done properly.

For a bathroom, you’ll need to add about £5,000 to the cost of building your extension’s shell. However, these costs can vary depending on the bathroom suite and finishes you choose.

A kitchen will cost you more than a bathroom, adding on around £10,000 to your fee for a low- to mid-range kitchen.

In addition to the costs of building the shell of your extension, you’ll need to consider the cost of any fittings.

If you’re building a 20-square metre kitchen extension, you should allow an extra £2,600 to £6,200 on top of the building costs if you’re on a strict budget (including labour, but excluding appliances).

If your budget is higher, you could pay anywhere from £5,600 to £12,000 on top of the cost of the extension (including labour, but excluding appliances).

Bathroom extensions tend to be smaller. The average costs of fitting a new bathroom suite range from £2,750 to £7,000 for a high specification finish.

Are you ready to get started on your house extension? HouseholdQuotes can help you find the right builders.

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What Affects the Cost of Building an Extension?

Quite a few factors come into play when looking at the overall cost of an extension. With the price per square metre of construction so high, it’s good to know what else might ramp the costs up for your project.

The Design and Planning

The cost of hiring a surveyor, structural engineer and architect will all need to be considered within your project. Getting hold of the relevant planning permission (if required), building regs approval and party wall agreements will also factor in, costing both time and money.

The Extension Size, Shape, and Height

Typically, the size, shape and height of your extension will bring your costs up. The larger you go, and with more premium materials, the higher your cost will be.

Similarly, the type of building materials – brick face, timber clad, glass – will affect your price.

The Necessary Groundworks

The groundwork, such as digging a foundation, improving drainage, or underpinning will all play into your final cost.

If you’re looking to build upon an area of uneven terrain, expect your prices to be higher than if you were building onto something existing and flat.

Any Tricky Trees

Trees can sometimes be even trickier than the extension itself. Many trees are protected by Tree Preservation Orders (TPOs), so make sure you take any tree into account when you are requesting planning permission.

If you remove or alter a tree without the correct permission, you could end up in big trouble.

Any Building Site Constraints

Do not forget to factor in additional costs for your site. If you have a complex site, you’ll need to ask your builder to factor in any extra costs.

For this, issues may include:

  • Soil type that demands a specific building technique or material
  • Changes to the existing structure – any changes to steelwork or walls or will see additional costs
  • Ease of access to the actual site (your house!) – if it’s difficult to manoeuvre tools and materials, you should plan ahead so work isn’t delayed
  • If you’re moving drainage, pipework, gas meters and so on this will require extra planning and cost

The Windows and Doors

Windows and doors can be pricey and easily increase the cost of even a modest extension.

Choosing larger windows, triple glazing, or bi-fold doors can further increase your costs.

If you want to bring light but keep costs down, ask your builder whether a small bit of bespoke glazing could work in combination with standard-sized windows and doors.

The Fittings and Fixtures

As briefly mentioned above with kitchen and bathroom extensions, it’s all the little extras that can sometimes add up and lead to a hefty bill.

If you’re happy with simply painted walls, carpet or engineered wood floors, and standard lighting and electronics then your costs will be relatively low.

More luxurious touches such as bespoke flooring or tiling and fitted joinery can add a unique look to your extension but also increase the costs.

Finding the Right Tradespeople

Depending on the type of work you’re having done, you may need different types of tradespeople involved in your project. Builders, plumbers, electricians, heating engineers, painters and decorators – they all come with their own skill sets and their own pricing strategies.

It’s good to note that small vs large contractors will offer very different prices. Where possible, opt for the smaller companies as they won’t have large overheads to recoup with their pricing, and will generally cost you less than the bigger national companies.

Your Location

An unfortunately inescapable fact is that your location will dictate your price – living in London will ramp up your project costs considerably.

Also, remember that if you don’t have off-road parking available at your home or site, you will be expected to pay a parking permit for your contractors over the duration of their stay.

Consulting Home Insurance

You should inform your home insurance provider of the building work, as your insurer may need to adjust your cover and premiums accordingly.

How Can I Save Money on an Extension?

Comparing quotes is a great way to potentially reduce the cost of your home’s extension. HouseholdQuotes can help you get quotes from multiple builders near you, so that you can find someone that suits your budget.

Click the button below to get started:

Comparing Quotes Could Save You Up To 40%:

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You can see how costs can spiral when getting an extension added to your home, so it’s important to also know the ways in which you can bring those costs down.

The devil is in the details—so plan ahead to avoid any costly last-minute changes. If you have your architect drawings complete and finalised, it can be expensive to have them changed, so make sure you really assess things at each stage of the sign-off process to make changes when it’s most easy to do so.

Similarly, if you know you want to use your extension for a certain purpose – like as a kitchen or a bathroom – it’s important everyone knows this beforehand so that certain considerations can be taken into account when building to ensure electricity, gas and water can be accessed in the space.

Don’t cut costs when it comes to the structure. Hire a surveyor and structural engineer or architect to draw up plans – you can look to save on fitting costs if you’re on a tight budget, but you shouldn’t try to scrimp on the structural integrity of your extension.

Permitting this is within your allowable home development, it might be more cost-effective to undertake a conversion over an extension when looking to add space to your home. Basements, lofts and garages are all perfect spaces to do this – so make sure you explore your options before going down one route.

Where possible, it’s best to avoid the need to move gas, electric or water pipes. If you’re planning a kitchen extension, it’s best to do it as sympathetically as possible, and have your fittings put in place where they make the most sense for your existing pipework.

Take advantage of online marketplaces, or choose off-the-shelf products from high street retailers over bespoke options. This will help you to save considerably on your fixtures and fittings. Similarly, you can buy ahead during sales or percentage-off periods at shops, which will also save you money in the long-run.

What’s Involved in Adding an Extension?

The steps will differ depending on the scope of your extension, but you can expect some, if not all, of the below to be involved when adding an extension to your home.

Firstly, you need to obtain Building Regulations or Planning Permission (if required), while also checking your leasehold agreement (if applicable) to make sure you can do what you want to do.

You can then enlist an architect to draw up plans, considering your intended use (kitchen, bathroom, study).

Make sure you consult your insurance provider to let them know of the planned work ahead of it beginning and obtain parking permits if required for your contractors to ensure they have easy access to your property.

Before work begins you may need to clear the space and excavate if necessary, including the removal of trees (if not held under TPOs or in protected areas).

Once all these elements have been completed, building work can begin.

Is a Home Extension the Best Choice for My Home?

It can feel overwhelming trying to decide whether or not undertaking such a big building project is actually the right move for you. We’ve listed the advantages and disadvantages of home extensions in the table below to help you come to the right decision.

Advantages Disadvantages
Home extensions can add value to your home They are expensive to complete
It is more affordable than moving house Home extensions can be stressful projects to undertake
There is huge scope for creativity and personalisation You may not be able to get exactly what you want

One of the key advantages to home extensions is that they can add value to your home. Most home extensions increase the sale value of your property, meaning that if you do end up selling the house it will make you more money.

In most cases undertaking a home extension is more affordable than moving house. Instead of searching for the right property and dealing with the stress of moving, you can simply extend the house to fit your specification.

This also means that the scope for creativity and personalisation of the property is endless. You can have your dream home without having to move neighbourhoods.

Whilst a home extension may be more affordable than moving house, they are still expensive to complete and will involve huge costs depending on what work you choose to have done. Budgeting is absolutely vital for home extensions so that you don’t end up spending thousands more than you wanted to.

Another disadvantage is that home extensions can be stressful projects to undertake that are time-consuming and involve a lot of planning and you may not get exactly what you wanted (depending on building regs and planning permission approval).

How Do I Find and Hire a Builder?

Finding the right builder can be challenging. At HouseholdQuotes, we can connect you to builders in your area.

Click the button below to tell us more about your project, and we’ll help you find someone quickly and easily:

Comparing Quotes Could Save You Up To 40%:

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When seeking out a contractor for your work, you should look to get three to five quotes for any extension to your home. That way you can get a feel for what the market rate is, as well as see who you get on with the most or feel is most capable of the job.

It’s important you don’t confuse an estimate with a quote. It’s fairly common for tradespeople, surveyors, and architects to offer an estimate the first time they visit your property. This estimate is a good starting point, but if you think they might be a good fit for the job, be sure to ask for a detailed quote so you can get a more precise idea of the costs.

It’s also worth making sure you have someone else with you when you get quotes. It can be helpful to have another opinion on price, timeframes, and personalities. What’s more, asking a family member or trusted friend to join you might help you feel less pressured to make a commitment on the spot.

When looking for contractors, you can ask your friends and relatives – even neighbours – if they’d had work done recently of a similar type and whether or not they’d recommend their professional to you.

This can help you in your search by speeding up the process if someone you trust has used someone who can do exactly what you need doing in your home.

Ensuring the Professional Is the Right Fit

First things first, a written quote is an essential part of any job. You should never accept a verbal agreement as your binding terms when undertaking any work, let alone an expensive home renovation.

With a written quote, you have something firm to refer to if needs be, simply stating what is and isn’t included in your quote, as well as for what fee and under what time frames.

Just like with a job interview, it’s good to find out your contractor’s experience, and whether or not they’ve built something like the structure you’re wanting for your home extension. Even if you have a brilliant verbatim recommendation from a friend or neighbour, if the contractor isn’t familiar with what you want, they mightn’t be the best fit for you.

Similarly, anyone can write something that sounds good on a website – but the proof is in the finished project. Asking for photos or videos of the contractor’s past work can further help to ensure you’re getting exactly what you want from your trader.

You should finally always double-check your professional has insurance to cover both themselves and you in the event of any trouble while constructing. This will also help you sidestep any cowboy traders, as they likely won’t bother with insurance and will get tetchy if you ask to see proof of it.

Final Checklist

If the answer to your lack of space at home lies in an extension, here’s our final checklist to make sure you’ve considered everything before embarking on your project.

  • Is an extension the right solution? Alternative space-making options can be loft conversions, basement/cellar conversions, as well as making use of an unloved garage. Make sure you’ve considered these avenues before settling on an extension first
  • Single or double storey? Think about the functionality of the room and what you want from it. If it’s a kitchen, make sure you consider the cost of new appliances and fixtures when looking at your budget
  • Make sure you have the correct building regulations before you get started on any work to ensure there are no hitches along the way – or wasted time and money
  • Find a contractor using HouseholdQuotes to help you save up to 40% off your project’s fee
  • Make sure you get a written quote from your trader before starting any work to safeguard you and your money
  • Enjoy your newly-created space!

Use HouseholdQuotes to find local builders and potentially save money on your home extension.

Comparing Quotes Could Save You Up To 40%:

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Frequently Asked Questions

Do I Need Planning Permission or Building Regs Approval for My Extension?

Adding an extension to your home falls within permitted development, so it doesn’t require planning permission—as long as it meets certain criteria.

You will require building regulations to get started on your extension project, however, with rulings on doors/windows, drainage, electrics, walls and roofing, to name a new factors.

You can read more detailed advice on the Planning Portal website.

How Does a Bungalow Extension Differ?

Bungalow extensions can expand upwards and outwards, making them very similar to that of a two-storey house. There are a few more things to consider, however, such as removing parts of the existing roof to make room for a new storey, as well as getting planning permission for adding height onto your bungalow.

For more information, take a look at our dedicated bungalow extension page.

What Are Some Alternatives to Building an Extension?

If an extension is a step too far for you right now, there are alternative ways of adding some extra square footage into your property.

Instead of adding space outside, you can venture into the basement with a cellar conversion, or upwards with a loft conversion. If you have a garage that is more of a dumping ground than it is somewhere to store a vehicle, then turning that space into a useful room may be an option, too.

For something quite a lot like an extension, but not quite with the same level of commitment, you can opt for a conservatory or a lean-to, instead.

Could an Extension Add Value to My Home?

In short – yes. According to the insurer Hiscox, adding a bedroom could add up to 11.8% to the value of your home.

Adding a kitchen or dining room extension could increase the value of your home by up to 10.8%, while adding a bathroom could increase the value by up to 5.7% (all figures based on the average UK home value of £226,071 as priced in 2017).

Do I Need to Let My Neighbours Know I’m Planning an Extension?

If you’re planning to extend your home and live close to or are attached to your neighbour’s properties, then it’s likely that you will need to notify them of your plans. They then might request additional information from you which could take more time and could also increase your costs.

Your best bet is to keep your neighbours as informed as you can, as early on in the process as you can. Whilst they can’t stop from you building an extension, they do have the right to be aware of what you’re planning and request further information or action if they want to.

How Close to My Boundary Can I Build?

The general rule to go by is that a build that reaches 7. 2 feet is considered acceptable, and anything over this will require you to speak to your neighbour. An extension of more than one storey cannot go beyond the boundary at the rear by more than 3 meters.

What Is the 45 Degree Rule?

This is a common rule used by planning offices and is assessed on both plan and elevation. An extension should not exceed a line taken at 45 degrees from the centre of the nearest ground floor window of a habitable room in an adjoining property.

If a proposed extension breaks this rule, it could be deemed unacceptable and not receive the permissions required to build.

Ready to start your project? We can help!

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How Much Do House Extensions Cost In 2022?

How Much Do House Extensions Cost In 2022? | MyBuilder. com

The average cost of a house
extension in the UK is £30,000

The home extension costs in this article are correct as of 2022

Building an extension is a popular way for families to get the most out of their homes, giving them extra space without having to move.

Extensions vary widely, so how much it costs to extend your home depends on a few key factors:

  • The size of the extension
  • The quality of the build and finishing elements

We’ve spoken to some of the expert extension builders on​ to get an accurate price guide for an extension job, including a handy house extension cost calculator. Here’s what you need to know.

Home extension cost per square metre

Extensions are complex projects that encompass a variety of different elements and trades, from laying foundations and building walls, to plastering, electrics and plumbing – and that’s before getting to decoration, or features like adding a new kitchen.

A large variety of things can affect the costs – from ease of access, to your choice of kitchen counter, but the essential costs are based on the size and quality of your build, as in the following breakdown:

  Small (3mx5m) Medium (4mx6m) Large (6mx8m)
Basic £14-£18.5k £22-30k £44-60k
Standard £18.5-£24k £30-£39k £60-£77k
Premium £24-£34.5k £39-£55k £77-£115k


In this article, we have broken down different elements of an extension build and the different kind of costs involved, but the key underlying cost relates to the size of the extension being built.

Speaking to our experts, we have established that the basic price of building an extension is £1,300 to £1,600 per square metre. So, for a 20msq extension (4m x 5m), the cost will range from £25,500 to £32,500.

These prices don’t include VAT, charged at 20%. The price bracket reflects the variance of materials used, the complexity of design, quality of finish and where in the UK you live.

This price covers the essential elements of the build, constructing the foundations, building the walls, insulating the new structure, fitting out with plasterboard, adding a subfloor, and installing a basic provision for plumbing and electrics.

It will not include any of the finishing elements, such as decoration or kitchen installation, which we cover later in this article.

MyBuilder Top Tip 

Twice the height, half the price? Some people suggest that adding a second storey to an extension will only cost a fraction of a single-storey build, but the specialists on describe that as a myth.

The key factor is overall floorspace, so if you’re thinking big, make sure you have the budget to match.

Stages of a house extension project

An extension building project goes through several stages of building, which are broken out below. Establishing individual prices for each section is difficult, as many builders will not separate costs for elements such as groundworks, which are rarely done in isolation from the rest of the project.

However, if you are having an extension built, many homeowners will agree to pay their tradespeople in stages, typically after some of the following elements are competed.


Home extension design costs

You may choose to have an architect or architectural technician draw up plans for the builders to follow, rather than hire a firm to design and build your extension. Architectural drawings may come in around £500 to £1,000 depending on the scale and complexity of the work – for more information, read our guide on how much an architect costs. 


Home extension planning costs

Planning permission is not always necessary for an extension project, but in some cases you may need permission from your local authority, which can be around £200 depending on your circumstances, such as if you live in a conservation area. Check out our guide on planning permission. 

Building regulations are the standards to which all construction projects must adhere and are essential for all building projects in the UK. Building Regulations are designed to ensure buildings are safe, structurally sound, and water and energy efficient.

The cost will vary depending on the size of the build and the type of work being carried out, but will typically be between £300 and £500.


Home extension groundwork costs

The preparing of the site and digging of foundations is essential to making sure the extension is built safely and with structural integrity.

Though costs for this phase are difficult to separate out, if there are complications at this stage, such as having to move drains or deal with tree roots, it can slow down the process and increase the cost.


Home extension construction costs

This is where the main building takes place, building the basic structure with either brick and block or a timber frame.

A roof is built, and interior elements such as plasterboard and a subfloor are added to ensure a watertight structure.

Costs here are typically related to the size of the build.

Nowadays, both brick and blockwork or timber frame extensions are at a similar price point, so while they may have various advantages and drawbacks in certain situations, the main building material choice should not be too much of a cost consideration for the average extension job.


Home extension fitting costs

Fitting out the extension with features like skirting boards, doors, electrical sockets and switches, as well as necessities like radiators. T

he costs of all of these will depend on whether you want to purchase high-end materials or not.

Sliding or bifold doors can cost thousands of pounds per metre, while simple French doors will cost much less.


Home extension finishing costs 

There is no upper limit to what you can spend when finishing the extension – every individual element will have a wildly different cost, from cheap carpet that is a few pounds per square metre, to imported marble tiles that will costs hundreds of pounds to cover the same space.

Costs will also increase significantly if you are adding a new kitchen or bathroom to the extended space. As a benchmark, a new kitchen could cost between £8,000 and £29,000, while a bathroom could cost between £3,500 and £11,500.

How long do home extensions take to complete? 

The length of time it takes to build an extension will obviously depend on the scale of the build, without even including any time spent drawing up plans and obtaining planning permission (which can take several months in and of themselves).

A rough time-frame would be between three and four months, from the start of the project – clearing the space and digging the foundations, adding the finishing touches, and dealing with any snags you encounter.

Delays are common, and are often due to bad weather, changes in the plans, and hold-ups in materials being delivered.

With multiple trades working on an extension, backlogs can also occur; for example, plastering can only be done after the electrics and plumbing are in place, so a delay to one will create a knock-on effect for other work to be finished.

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How do different home extension types vary in cost? 

While a price per metre is the best way to roughly work out the cost of an extension, there are a number of different types of extension which can have some bearing on the final cost.

Side extension vs rear extension costs

As the main calculation for pricing an extension is based on floorspace, whether an extension is to the rear or side of a property will not have a large impact on the overall cost of the build.

There will be other factors that affect pricing depending on the design of the extension though, such as how integrated with the original building it is and what structural implications this has, how many windows and doors it has, if a new kitchen or bathroom will be in the extension, or how difficult access is.

Double vs single storey extension costs

Many sources claim that a second storey will be priced at only half or two thirds of the cost of the first floor (so if the single storey extension is 20msq and costs £25,000, the second floor could be an additional £12,500, for a total of £37,500).

However, tradespeople we have spoken with tend to disagree, and say that the majority of extension builders will price a job based on the total square meterage – so a two-storey extension with both floors of 20msq floor space will be £50,500.

While it may seem intuitive that the ground floor is the more labour intensive element because of the groundwork and foundations that must be completed, there are a number of additional costs involved in a second storey that are not applicable to a single storey project.

Using scaffolding, working at height, increased structural integration with the original building, changing the roof – all of these factors serve to ultimately balance out the cost.

Masonry vs timber frame extension costs

Masonry, or “brick and block” construction has been the most common way of home-building in the UK for nearly a century, but timber frame projects are becoming more and more common.

Masonry construction sees the structural element built from blocks, with brick or another form of exterior cladding added around it, whereas timber frame uses wood to construct core panels that are assembled on site.

Both have benefits and drawbacks in terms of speed of construction and their structural benefits, but in terms of cost, as stated above, the two methods are fairly equivalent.

Bathroom and kitchen extension costs

The two biggest additional factors that can impact the overall cost of an extension is if you plan to install a kitchen or bathroom in the new space.

The price of new kitchens and bathrooms vary widely depending on your requirements and the quality of the products you choose to buy.

As mentioned earlier, the  typical price range for fitting a bathroom may range from £3,500 to £11,500, while a kitchen could cost anywhere from £8,000 to more than £29,000.

For more detailed pricing for kitchens and bathrooms, take a look at our pricing guide for kitchens and bathrooms.

Garden room extension costs

Garden room style extensions tend to be very design-focussed, typically single storey with an emphasis on large windows or bifold doors that allows the house to flow out into the garden.

Although you can still use the basic calculation of price per square metre, there are a number of complicating factors that will impact the final price of a garden room project, such as the materials used and the desired features, such as what kind of doors will be used.

Bungalow extensions costs

As above, the main calculation for extension pricing is based on cost per square metre of floor space, so the cost for a bungalow extension can simply be considered along these lines. 

How to keep your home extension costs under control 

It is important that you only embark on any major project, like building an extension, when you are fully aware of scale of the job and the costs involved.

Set a budget and get several quotations for the work. Allowing yourself a contingency is always a wise move, to help you cover any extra expenses that could arise as a result of delays or issues with materials.

There are ways to save money on a project like an extension build, but it is worth remembering that in order to save the money, it will require you investing more time and effort into it.

For example, you could choose to carry out some of the jobs yourself, such as the final decorating, if you are happy that you would be satisfied with the finish and wanted to spend the time doing so.

You could also source materials, such as tiles and flooring yourself, though a tradesperson may be able to help you with this, and may actually save you money via a trade discount.

The best way to ensure the job is done to budget and with no extraneous costs, is to hire good tradespeople you trust to do the job well. A

good team, who work well together and stick to a timetable, and ensure different phases are ready for other elements of the work to begin, will be the best guarantee of not encountering unexpected bills. Find a quality extension builder to quote for your job today.


Choosing the right builder for your home extension

Quotes and contracts

How much does an extension cost? Start a ballpark budget with our guide

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It’s tempting to answer that question with a question: ‘How long is a piece of string?’. But actually, unless you have a unique and innovative architectural showpiece in mind, it is possible to estimate how much an extension costs with some level of accuracy.

Breaking down the ballpark costs at the start means you’ll know what kind of market you’re in when it comes to the interior fittings and help you to prioritise how your budget is spent. There’s no getting around the fact that we’re talking double figures here, whatever kind of extension you have. And that’s scary.

But the good news is that there are plenty of ways you can trim the costs and still have a great quality addition to your space. Here are the answers to all the big questions…

(Image credit: Future PLC)

How much does an extension cost?

The cost per square metre of an extension will fluctuate depending on the property market in your area. So even extension ideas for small houses can prove costly depending on where you live. Architect and director of DesignFor-Me (an architect-finding service) Emily Barnes says ‘The rule of thumb is now £1,500 per square metre for a basic to mid-range extension. In London and the Southeast, this rises to £1,800-2,000 per square metre.’ So, if you are outside London/Southeast, according to DesignFor-Me:

What 30k will buy you…

A basic, 4m x 5m single-storey extension. This covers build costs only and none of the extras and interior fittings (see below).

What £55-60k will buy you…

A small 3m x 6m two-storey extension (build costs only)/

What 70-80k will buy you…

A small 3m x 6m two-storey extension with architect-designed cladding, bespoke glazing and a designer kitchen.

In London and the Southeast, you’ll pay more than the rest of the UK, due to higher labour and material costs. Robert Wood, MD of London-based construction company Simply Extend says, ‘Including VAT, a single-storey side return extension starts at £44k, a rear extension starts at £55-60k and a wraparound extension, which is a combination of a rear and side extension, connecting at the corner, costs from £65k.

Try Homebuilding & Renovating’s extension cost calculator to get an estimate of your project.

How much does it cost to hire an architect?

Architects’ fees scale according to the total budget of the project. According to an independent survey by research company The Fees Bureau average charges break down as follows: £25k project, 10.7%; £50k project, 9.9%; £75k project, 9.5%; £150k project, 8.7%. 

Your final bill will also vary depending on the location, the complexity of the project and the level of service you opted for. The architect will usually put forward an itemised proposal breaking down the different stages of the work and their percentage of the total fee. This is to help you budget, but also makes it easier to decide if you want to opt out of parts and source them differently.

In simple terms, the stages are: Concept and design, technical plans for approval, and construction management. So, you could work up your own simple concept and even use free online software to create a design plan, then hand over to the architect for full tech specs with structural calculations, building regs and project management. Or, you could use them for the initial stages, then hand over to your builder for the rest. 

In fact, you don’t HAVE to hire an architect at all. There are other routes: for example, if you know what sort of design you want, you could hire a structural engineer instead. According to , this will cost between £400 and £4,000, depending on the complexity of the project.

You could use a design-and-build company if your project is simple, or commission a firm of architectural technicians to supply technical plans. There’s a whole raft of these online, offering packages for just a few hundred pounds.

However, bear in mind that if your extension is big or in any way out of the ordinary, an architect can save you money by giving you the best ideas for the space you have and controlling costs from start to finish.

(Image credit: Future PLC)

What additional costs are there?

At the very minimum, you’ll also have to stump up for…

Planning and approvals fees

  • Submitting a planning permission application for an extension will set you back £206. Or, if you’re building under Permitted Development rules , it’s advisable to get a certificate of lawful development for your extension, at half the cost – £103. 
  • According to the HomeOwners’ Alliance , the fees for building regulations approval costs around £100 to submit your plans, then £200-400 for site inspections. This varies from one authority to another, though.
  • You’ll need a party wall agreement if your extension will be at or close to a shared wall. Liaise with the neighbours directly, well in advance, to maximise the chance of them assenting to your official notice. Otherwise, you’ll have to pay surveyors’ fees (£150-200 per hour) and the cost of a party wall award (about £1,000).
  • Drain surveys are increasingly popular with architects. It involves putting a camera through to check the depth, flow direction, size and condition of pipework before planning additional drainage. This might lead to relocation of drains, which will add a cost.
  • It is a statutory requirement to consider the ecological impact of your project and it’s possible you’ll need a Wildlife Assessment Check. Use Biodiversity in Planning’s free online tool to see if you’re likely to need one.
  • If your home is listed you might need an Archaeology and Historic Buildings Report.

(Image credit: Future PLC)

Don’t forget to factor in the cost of fittings and furniture for your new space


Don’t get caught out – check all quotes as they’re likely to be exclusive of VAT.


Any new space is going to need power. Plus, brace yourself for the possibility that your electrician will find a problem with the existing wiring that needs sorting.

Interior fittings

You’ll have kitchen cabinetry and appliances (average £10k), a new bathroom suite (average 5k), or new furniture to buy. Plus heating (underfloor or rads), flooring and lighting. 

Other possible costs:

If you’re adding a bathroom, also factor in…

  • Plumbing costs
  • Upgrading your boiler and, if you have one, shower pump to cope with the extra hot water

If you can’t live in the house while the work is done, you’ll also need to budget for removal and renting elsewhere as well as updating your insurance policy to cover your property during the work.  

Related: Kitchen extension ideas – to maximise the potential of your extended space

What’s the cheapest way to build an extension?

There are lots of ways to shave costs down – here are 16 for starters. Some will be doable for you; others won’t:

1. Consider if you REALLY need one

Can you get the extra space you need with a garden building, garage conversion instead or conservatory instead? These are all considerably cheaper options and usually fall under Permitted Development Rights, so you won’t have to get planning permission.

Could your space needs be served by a conservatory instead?

(Image credit: Future PLC)

2. Build it yourself

Chris Thompson, a keen DIYer, tackled a two-storey addition to his period cottage himself and chronicled the experience in his blog, .

‘The obvious pro is financial,’ he says. ‘General estimates are that 80% of a builder’s quote is to cover labour costs, so you’re saving that. However, the con is that it will take longer. If you’re realistic about timescales and know what you’re getting into, that doesn’t have to be a problem, though. Builders have to work within a timeframe to make money; you don’t. You’ll be able to do things exactly as you want them done and have pride in the result. I know mine is done properly.’

3. Avoid site snags

A clear site makes for easier groundworks at the start. When planning the footprint of your extension, you’ll save money if there are no trees to take out or drainage to move. You could also save on labour costs if you remove shrubs and paving yourself.

We’d all love an architecturally interesting glass-and-steel edifice, but unfussy extensions with 90-degree angles rather than clever curves and slants will be quicker – and therefore cheaper – to build. Elegant curves cost more than simple right angles

(Image credit: Future PLC)

5. Don’t make it bigger than you need

It’s important that your extension is in proportion to your property anyway, but the smaller the job, the quicker it’ll go up.

6. Triple-check the plans

Making sure every detail is spot-on before ground is broken means you’ll avoid changes of plan as you go. For water and sewage pipes particularly, this can be expensive and cause frustrating delays.

7. Do the work in summer

Timing the groundworks, build and roofing to take place during the summer months will reduce the chances of your project being paused due to heavy rain, wind, snow or frost. 

8. Work to a schedule of costs

Choose a builder who will give you a fixed price and work to an itemised list of costs agreed up front, to avoid unexpected extras as the work progresses.

9. Be picky about who you hire

A great builder or architect will be able to do quality work that meets building regulations first time, control costs and be alert to ways to save you money along the way.

10. Be your own project manager

Usually, the building firm or architect you employ will provide the services of a project manager, but if you have the time and organisational skills, you could DIY. It would involve liaising with the architect (if you’re using one), working with the local authority’s planning and building control officers, finding tradespeople, directing the schedule of work and sourcing materials.

11. Choose wood instead of block-and-brick

Timber-framed extensions cost less, even though the materials are more expensive, because they are quicker to build so give lower labour costs.

Tim Bromley, Federation of Master Builders member and MD of Wolfe Design and Build , says: ‘For larger extensions, timber frame can be a quicker option. It doesn’t suit every project, however. Traditional block and brick methods offer greater flexibility when attaching an extension to irregular profiles, such as period properties.’

Building an oak-framed extension can be cheaper than bricks and mortar

(Image credit: Border Oak)

12. Try ICF blocks instead of concrete blocks

Insulating Concrete Formwork’ blocks are essentially polystyrene Lego bricks that fit together to create a double wall that’s filled in the middle with poured concrete. It’s a quick, low-skilled job for reduced labour costs. It’s also great for heat and sound insulation.

Tim Bromley, a member of the Federation of Master Builders and MD of Wolfe Design and Build comments, ‘The key advantages of ICF blocks are build time and thermal efficiency for large extensions, but the thickness of ICF walls does reduce the internal space. Maximising space is often key in this kind of project, so that’s an important consideration.’

13. Choose cladding or render instead of brick facing

Dressing the block work structure with shiplap cladding or simple render works out cheaper than skinning it with an outer layer of bricks. Expert Tim Bromley confirms, ‘The most cost-effective method for a block-work extension is exterior render, including those with a timber frame.’

Finishing an extension with render rather than brick facing can reduce costs.

(Image credit: Future PLC/ Tibor Silva/Simply Extend)

14. Don’t mess with pipework

When it comes to arranging the interior of your new space, leave soil stacks and pipework where they are – even if it means compromising your dream layout – to avoid spending on relocating them.

15. Buy off-the-peg doors and windows

Bespoke glazing is budget-busting, but you can still achieve a light, airy space with Velux roof lights and ready-made windows and doors. If you’ve got your heart set on bifolds, expect to pay around £2,750 for a 2.7m aluminium frame unit or £1,650-2,000 for UPVC.

Choose ‘ready to assemble’ units and fit them yourself if you’re a competent DIYer to save on the additional installation costs. Sliding, rather than folding, aluminium-frame doors tend to be 25% more expensive. Velux centre-pivot roof windows are a cheaper option to bespoke glazing.

(Image credit: Velux)

16. Trade down on interior fittings

Fitted joinery and tiling are beautiful, but labour-intensive. Paint walls rather than have them tiled, choose carpet, LVT (luxury vinyl tile) or engineered wood flooring, and find off-the-peg cabinetry you love.

Painted walls and off-the-peg cabinetry will bring your project in on budget.

(Image credit: Future PLC)

Is it cheaper to extend up or out?

Robert Wood, Managing Director of London-based construction company Simply Extend says, ‘It is in general cheaper to do a loft conversion due to the fact that no foundations are needed as you are building on top of an existing structure.

Most loft conversions also don’t need planning permission. However, if your loft conversion would involve changing the roof structure, costs will go up.

How much value does an extension add?

There’s not much new research on this, but a 2017 Home Improvement Index survey by Zopa of 1,550 homeowners revealed that an extension added an average of 16% to the property value and gave a 57% return on investment. 

An older report – Nationwide’s House Price Index from 2014 – found that extending out or up added 21% to the property value, or 5% for every 10% increase of floor area.

Obviously, the added value will depend largely on where you live and the type of space that’s in demand, so it’s worth researching the sold prices of houses in your area and looking at what improvements they’ve had. Unless you’re in your ‘forever’ home, it pays to think strategically and add larger kitchens and extra bathrooms in family homes, or a garage in areas with restricted parking.

How Much Does an Extension Cost? What You’ll Pay in 2022

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(Image credit: Ollie Hammick c/o Amos Goldreich Architects)

It’s the big question before you consider extending your home: how much does an extension cost? Well, it depends… 

Before you can get a clear answer about the costs involved for your extension, you’ll need to consider different variables. How big your extension is, for example, the materials you’re using, the volume of glazing — every choice will affect the final price when extending, and that’s before you get into additional costs such as surveys, structural engineer fees, planning permission and more. 

However, it’s important to be able to have a grasp on how much an extension costs to decide whether its viable at all to be building an extension to your home, so with that in mind, we’ve created an easy reference which offers some ballpark figures you can use to start to consider your project.  

While these figures may not match up perfectly with your builders quotes or estimates, and may differ depending on where you live in the UK, they should give you a good indication on the costs involved. 

Once you’ve got an overview, you can also use our extension cost calculator to get a more detailed estimate of how much your extension will cost. 

Is an Extension Right for Your Home?

Before getting too wrapped up in the specifics of how much does an extension cost?, take time to consider whether an extension is financially viable and right for your property. 

Is this your forever home? If so, an extension is a no-brainer compared to the hassle of moving house. In a financial sense, opting for an extension means you’ll save on moving costs, solicitors fees and stamp duty — costs which aren’t recouped by adding value in the same way as your extension. However, consider that increasing the size of your home may move you into a higher council tax bracket.

If you are planning on selling up, whether soon or in the future, you’ll need to ensure that you add more value to your home than the extension costs. Speak to local estate agents and research ceiling prices in the area before you decide to go ahead.

Open up an extension, connecting inside and out, with bifold doors like these SUNFLEX SF55 Aluminium bifold doors by IDSystems . (Image credit: IDSystems)

How Much Does an Extension Cost?

In short, most extension projects cost around £1,350-£2,250/m² of new internal space. So a 30m² kitchen extension could be estimated at somewhere between £40,500-£67,500, plus, VAT at 20%. 

If that sounds suitably general — that’s because it is. And that’s all you can expect when you have no detail or idea of what the extension looks like, or what materials you’re going to use, or how it is going to be built (and who’s going to do it). The £1,350-£2,250 price, however, is a very good range of pricing based on averages.

There are multiple factors that can affect your project’s costs, including:

  • How many storeys you’re going to build 
  • The size and shape of the extension
  • The quality of the build: standard, good, excellent
  • The build route you’ll take —  how involved in the project you’ll be
  • The amount of glazing you’d like
  • Whether the extension contains a kitchen or bathroom 

There are other costs to consider outside of the build itself.  

Here are some example costs you might need to factor in:

  • architect fees (around 7% of construction cost)
  • structural engineer (£500-£1,250) 
  • surveys (between £700-£1,800)
  • planning permission (if needed — currently £206 in England for a two-storey extension, but check with your local authority).
  • Building Regulations applications
  • Lawful Development Certificate (currently £103)
  • fitting out the extension (costs will vary depending on how you plan on using the new space)
  • Party Wall Agreement (if needed — £1,000-£2,000 per affected neighbour for a straightforward agreement outside London).
  • insurance

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If you’re planning on building a fairly straightforward, box-shaped, single storey extension then allow for around £1,350-£1,750/m². Do bear in mind that this price will fluctuate depending on where you are in the UK and the standard of build you opt for.

In certain parts of the South and high value areas of the UK – affected by higher cost of living – this you could easily be paying £1,700-£2,500/m², particularly on smaller single storey extension ideas. That makes an 8x4m kitchen extension a £43,000-£80,000 project.

(Image credit: Mo Photo c/o Ke-design)

  • Basic quality: £1,350 to £1,650/m²
  • Good quality: £1,700 to £2,000/m²
  • Excellent quality: £1,800 to £2,500/m² or more.

For an excellent finish you can typically expect to pay 40% more than a standard finish.

How Much Does a Double Storey Extension Cost?

A double storey extension won’t cost much more per m² than a single storey extension, at around £1,250-£1,650.

That’s because, aside from the extra interior fixtures and finishes, you are only adding walls and floor joists. A roof and foundations are required whether you build a single or double storey extension, but these elements will cost largely the same no matter which you choose.  

(Image credit: Charlie O’Beirne)

  • Basic quality: £1,250 to £1,650/m²
  • Good quality: £1,650 to £2,250/m²
  • Excellent quality: £2,250 to £3,000/m² or more.

How Much Does a Side Extension Cost?

The cost of your side extension idea depends largely on the size of the structure, the location of the build and the quality of the materials and finishes. 

“A basic range of costs might be £1,500-£2,000/m², with smaller extensions generally having a higher per m2 cost than larger ones,” says Nicola Chambers from Pardon Chambers Architects .

The likely cost of the works will also vary depending on the scope of the internal work and any reconfiguration that’s required. For example, the cost of simply extending your living space will be very different to the cost of re-locating and plumbing in a new kitchen. 

“On average, homeowners should budget between £75,000 and £300,000 for a side extension. The upper limit for the project cost could be as much as you’re willing to pay for your dream extension. In any instance, it’s important to set a maximum budget you’re comfortable with and to allow for a contingency fund,” says Adam Knibb from Adam Knibb Architects .

This clever extension created using IQ Glass ‘s structural glazing made use of the existing party wall to create an indoor-outdoors terrace in the previously unused side return.  (Image credit: IQ Glass)

How Much Does a Conservatory Extension Cost to Build?

A lean-to uPVC structure sits at the lower end of the price spectrum when it comes to conservatories and could be achieved for around £5,000. More complex structures, such as Victorian, Edwardian, L-, P- and T-shape conservatories are more likely to cost between £10,000 and £15,000 (in PVCu)

For an oak frame conservatory, expect to cost to be somewhere between £30,000 and £40,000. “A realistic cost for a 20m2 oak frame conservatory would be £2,500 per m2 (+VAT),” says James Underwood, a regional design consultant at Oakwrights . “This will deliver an above average build. It’s worth bearing in mind, too, that this average cost will fall with larger builds as the computer design and CNC machining costs are spread over a larger footprint.”

(Image credit: Mozolowski & Murray)

How Much Does a Basement Extension Cost?

“The cost of the basement can depend on numerous factors, including location, soil type, party walls, type of the property, site access, local authority restrictions and, of course, the size of the existing cellar,” says Stuart Braid, director at MoreSpace Basements . 

“The minimum cost to waterproof and prepare a cellar for decoration and finishes would be within the region of £20 – 25,000 upwards. For projects where excavation and underpinning are required to create more head height or enlarge the space, prices would start from around £3,000-4,000/m². Typically, costs would increase depending on the desired purpose of the new area. For instance, if a shower or utility room is required costs will go up due to the additional pumping systems required. ” 

(Image credit: French + Tye c/o Paper House Project)

How Does Your Construction System Affect Costs?

The construction system you choose to build your extension will of course have an impact on budget. 

If you want to build an extension fairly cheaply then opt for concrete blockwork. It’s a system most builders know well, too. Alternative modern methods of construction, like structural insulated panels, might cost more to begin with, but cost-savings might come from less labour time needed on site, especially when it comes to insulating your extension. 

Timber frame is another construction method you could choose. The cost of the frame, associated design work, delivery and assembly on site is charged as a package. On the plus side, this provides cost certainty.

How Does Your Cladding Choice Affect the Cost of an Extension?

The way your new extension looks from the outside is just as important as the space and light you create inside. While you’ll be seeing more of the internal finishes than the exterior ones, a well-specified, well-designed and well-built extension will not only add more value but give you more pleasure than one built without beauty.

When it comes to the finish of the extension externally, it is important to understand in the first instance that the external wall of the extension is not the same as the internal supporting structure. This means, for instance, that a home can have blockwork structural walls but be finished in, say, timber or stone, as well as brick.

The brick is not a structural element — it’s house cladding in the same way as everything else. So the choice is wide, and important and must be factored into the cost of your extension.

This contemporary extension to a bungalow has been clad in timber. (Image credit: Simon Maxwell)

How Much Difference Does Your Build Route Make to the Cost of an Extension?

The build route determines who will build and manage your extension project. How the extension is managed will have an impact on the budget so it’s an area most people agonise over for a while.

Taking on the project DIY-style could see a 40% variation between what is possibly the cheapest build route compared to taking on and paying for a main contractor.

There are four main build route options:

  • DIY: building on a largely DIY basis, substituting around 30% of the labour costs with DIY and employing help with the rest of the building work. Materials purchased directly
  • Self managed/subcontractor: building using tradespeople hired directly. Minimal DIY involvement. Most materials are purchased directly
  • Hiring a main contractor and subcontractors: building using a main contractor or package supplier to complete the extension to a weathertight stage, with the remaining work being undertaken by subcontractors with most materials purchased by self builder direct from suppliers
  • Hiring a main contractor: building using a main contractor. Building in this way requires the least involvement from the self builder.

(Image credit: Simon Burt)

How do I get a Quote for an Extension?

How much should your builder be quoting for an extension project? Firstly, be very wary about anyone giving too detailed an estimate at this early stage. An estimate is no more than a guess based on limited information and effectively worthless until you go to quote stage, which is a fully-fledged cost offer based on the facts of the construction project in detail. All of the decisions you will end up making, from the kitchen to the provision (or not) of underfloor heating, from the sliding doors to the lighting, will affect costs. And if your builder doesn’t know this, the estimate is no more than a finger in the air.

Engaging with a quantity surveyor on a larger extension project could really help with costs. Quantity surveyors provide an expert view on the costs of a construction project, which could help reduce the stress of budgeting for a build.

Put simply:

An estimate is normally a contractor’s guess as to what your extension will cost. Whether given verbally, or in writing, is not legally binding and the final bill may exceed it.

A quotation is a definite price. Written builders’ quotes should itemise the work to be done, provide a breakdown of costs and a total, and state whether VAT is included.

(Image credit: David Barbour)

How to Compare Extension Quotes

When you receive the bids, check whether there are any caveats that might involve extra expense. Compare provisional sums for work such as foundations to make sure you are comparing like with like

One really important thing to do when considering an extension project is to talk to a builder (rather than a designer). The builders will be able to give you a sense of the typical solutions for houses of your type and almost certainly have carried out similar projects in the local neighbourhood. They will be able to guide you on some of the practical issues you might be worried about (e.g. drains) and help you get an initial sense of what the project might cost. 

Designers will be essential at some part of the project, but not yet. These are not individual self build projects and bar the very few totally unique extension schemes, most are simple, practical and largely templated solutions to common house types and common spatial needs. At this stage you’re trying to get a sense of the feasibility of extending from an engineering and construction perspective, and no one is better placed than a builder for that.

Is an Extension Subject to VAT?

Most extensions will be subject to VAT on labour and materials at the standard rate of 20%, especially if you use a contractor to undertake the work.

If you use local tradespeople who are not VAT registered you can save the 20% VAT on their labour, but you will still have to pay VAT on materials at the standard rate.

Some extension projects are eligible for VAT relief, such as:

  • the conversion of an existing dwelling that changes the number of units
  • work to a building that has been unoccupied for at least two years

To benefit from VAT relief from the above, you must use a VAT registered builder — you can’t reclaim the VAT yourself.

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How Much Do House Extensions Cost? | 2022 Cost Guide

15th Jul ’22 • By Jared Jeffery

Whatever your reason for wanting a house extension, there is one component that you want to nail first. And that is budgeting for it. At the end of this cost guide you should have a clear understanding of every cost associated with a house extension. So let’s begin.

Are you thinking of getting a house extension in 2022 but want to ensure you can comfortably afford it? Well, the good news is that a house extension on the ground floor is significantly cheaper than a second-storey addition. Not only can a house extension provide more space for your family, but it can also work as a fantastic professional space, playroom and just about anything you can imagine! 

Cost of House Extensions

You can expect to pay between $2000 – $4000 per square metre, so an 80 square metre ground floor extension will cost between $164,500 to $310,000. There are a few factors that will affect your total costs, such as the quality of your inclusions and chosen construction. 

Get quotes from our qualified and licensed tradies Australia-wide.

Article Overview:

  • The benefits of a house extension 
  • How much does a home extension cost?
  • Estimates of the average house extension
  • Additional home extension costs
  • Considerations for your budget 
  • Finding the right builder for your house extension 
  • House extension FAQs

The Benefits of a House Extension

Other than the most obvious benefit of a house extension — more space — there are a number of advantages that come with an extra addition to your home! Three of the biggest benefits are: 

  1. You don’t have to uproot your family, life and possessions to move somewhere else! 
  2. You can transform your home into exactly what you want and like. 
  3. It can be less expensive than moving to a bigger home.  

Before you say “wait a minute, surely moving would be less hassle than having construction happening inside your home,” hear us out. There are a number of processes involved with moving. Firstly, putting your beloved home on the market, which can take a long time to sell. Secondly, the actual packing and moving part (did you know moving is up there with the top three most stressful experiences of a lifetime?). We could go on and on, but we think you get the picture! 

How much does a home extension cost?

We know you’re here because you want to know how much a home extension actually costs. Well, we cannot define the exact cost of your individual home extension without knowing the size, complexity of the job and chosen materials, but we can provide a rough guide. The standard cost of your house extension will typically include roofing, insulation, cladding, interior cladding, windows and doors. 

Estimates of the Average House Extension

  • 60m2 ground floor extension: $20,000 – $75,000 
  • 80m2 ground floor extension: $164,500 – $310,000 
  • Second storey extension: 50% more than ground floor 

Additional Home Extension Costs

  • Excavation work
  • Heating and air conditioning 
  • Additional costs for a bathroom 
  • Additional costs for a kitchen
  • Quality inclusions are more expensive
  • Drawing of plans or council fees
  • Having the extension furnished

Considerations For Your Budget 

  • Lighting costs 
  • Flooring costs 
  • Costs of furnishings 
  • Heating and air conditioning costs
  • Interior painting costs 
  • Exterior painting costs 

Finding the Right Builder for Your House Extension 

On Service., you can browse through a number of professional builders within your area. As always, we strongly recommend ensuring you take a number of quotes, do your research and ask questions. 

Some questions to ask a builder may include:

  • How long will my job take?
  • Are you insured and do you hold the relevant qualifications for this job?
  • Do you have references I can check?
  • Do you have examples of similar jobs I can see? 
  • How much will this cost? 

It is also worth noting that if a builder’s quote is significantly less than the other quotes you received and sounds too good to be true, it probably is. This builder may simply be undercutting their competitors’ quotes by leaving out extra costs and then adding them after work has commenced.

This is why you should always plan for every single cost and make sure it is covered in your quote. Additionally, higher quotes may not be unreasonable but rather a reflection of the builder’s experience, reputation and standard of work. Investing in the best possible builder for your house extension is always recommended by the team at 

Get Carpenter Quotes Now

House Extension FAQs

Should I extend my current home or move?

This is a question only you can truly answer, however, we have some tips for deciding. If you love the home you’re in, and have great neighbours and facilities nearby then an extension is a fantastic alternative to moving! Not only is moving extremely stressful but often more expensive and time-consuming than adding an extension to your current home. 

Do I need to move out of my home during the construction?

The simple answer is no, you do not need to move out during the construction phase of your house extension. However, we would recommend it, particularly if you only need to leave for a couple of weeks. This takes the pressure off you and the builders to ensure the work is safely and promptly carried out. 

What eco-friendly options are there for house extensions?

In order to make your house extension eco-friendly, you may wish to use recycled materials, install a water tank (if water is needed), use energy-efficient LED light bulbs and consult with your builder on what other options are available.  

Can I DIY a house extension? 

At we believe large projects like house extensions are best left to the experts. However, if you are an experienced home improvement DIYer with the right knowledge and tools for the job you may undertake the project or enlist expert help further on in the process. 

Should I hire an architect or a builder for my extension?

If you are opting for a complex design for your house extension, an architect would be the best option and then they will likely enlist a builder to carry out the construction. In most cases, builders are more than able to handle the extension process. 

When is the right time to add a home extension?

This depends on your circumstances. If you have considered all the costs and have a budget equipped to handle the task then there is really no time like the present! However, it is wise to consider your personal and work calendar and opt for a time that is less busy and more flexible to interact with builders and oversee construction.

How much does a house extension cost?

You will approximately pay between $2000 to $4000 per square metre, so an 80 square metre ground floor extension can cost between $164,500 – $310,000. There are a few factors that will affect the costs of your home extension, such as the quality of your inclusions and chosen construction.

Further Reading

  • How Can a Carpenter Help Make Your House More Sustainable?
  • Carpentry-Inspired Ideas for Your Home
  • How to Hire a Carpenter
  • 5 Most Popular Interior Paint Colours

Cost Guides

  • How Much Does a Second Storey Addition Cost? | Cost Guide
  • How Much Does It Cost to Hire a Carpenter? | Cost Guide
  • How Much Does It Cost to Hire a Builder? | Cost Guide
  • How Much Does a Granny Flat Cost? | Cost Guide


Prices for extensions to a house

Prices for extensions to a house

The Doma iz Brusa company offers services for the construction of extensions to the house. Here you can order an extension to the house: porches, vestibules, terraces, verandas, rooms.

Cost of an extension to the house per m 2 work + material
Porch 15 000 ₽ per m 2
Open terrace 15 000 ₽ per m 2
Closed insulated porch 25 000 ₽ per m 2
Vestibule (or room extension) 25 000 ₽ per m 2
Prices for extensions of standard dimensions work + material
Size, m Open annex (terrace, porch) Closed annex (veranda, vestibule, room)
1. 5×5 112 500 ₽ 187 500 ₽
1.5×6 135 000 ₽ 225 000 ₽
1.5×7 157 500 ₽ 262 500 ₽
1.5×8 180 000 ₽ 300 000 ₽
2×4 120 000 ₽ 200 000 ₽
2×5 150 000 ₽ 250 000 ₽
2×6 180 000 ₽ 300 000 ₽
2×7 210 000 ₽ 350 000 ₽
2×8 240 000 ₽ 400 000 ₽
2×9 270 000 ₽ 450 000 ₽
2×10 300 000 ₽ 500 000 ₽
2. 5×5 187 500 ₽ 312 500 ₽
2.5×6 225 000 ₽ 375 000 ₽
2.5×7 262 500 ₽ 437 500 ₽
2.5×8 300 000 ₽ 500 000 ₽
2.5×9 337 500 ₽ 562 500 ₽
2.5×10 375 000 ₽ 625 000 ₽
3×3 135 000 ₽ 225 000 ₽
3×4 180 000 ₽ 300 000 ₽
3×5 225 000 ₽ 375 000 ₽
3×6 270 000 ₽ 450 000 ₽
3×7 315 000 ₽ 525 000 ₽
3×8 360 000 ₽ 600 000 ₽
3×9 405 000 ₽ 675 000 ₽
3×10 450 000 ₽ 750 000 ₽
4×4 240 000 ₽ 400 000 ₽
4×5 300 000 ₽ 500 000 ₽
4×6 360 000 ₽ 600 000 ₽
4×7 420 000 ₽ 700 000 ₽
4×8 480 000 ₽ 800 000 ₽
4×9 540 000 ₽ 900 000 ₽
4×10 600 000 ₽ 1 000 000 ₽
What is included in the price of the outdoor terrace?
Base double piping
Legs board 40×150 mm (pitch 580 mm)
Finished floor terrace board
Support posts timber 150×150 mm
Terrace railing wooden balusters and handrail
Rafter system board 40×150 mm (pitch 580 mm)
Sheathing edged board 20-25 mm (pitch no more than 350 mm)
Roof ondulin / galvanized corrugated sheet / metal tile (customer’s choice)
Waterproofing under roof
Ceiling trim timber imitation
Counter rail +
Antiseptic +
Moisture content of frame wood and finishing materials forced drying
Height inside terrace from 2 to 3. 5 m (depending on the configuration of the house and the wishes of the customer)
Assembly +
Warranty 3 years
What is included in the price of a closed extension (veranda, room, vestibule)?
Base double piping
Legs board 40×150 mm (pitch 580 mm)
Subfloor edged board 20-25 mm
Finished floor Quick Deck 22 mm
Racks (outer walls) board 40×150 mm (pitch 580 mm)
Stabilizers (external walls) board 40×150 mm
Rafter system board 40×150 mm (pitch 580 mm)
Sheathing edged board 20-25 mm (pitch no more than 350 mm)
Roof ondulin / galvanized corrugated sheet / metal tile (customer’s choice)
Exterior finish imitation timber
Entrance door metal
Windows PVC two-chamber with fittings, cashing
Window sills and flashings +
Interior finishes (walls and ceilings) lining
Corners inside extension wooden plinth
Insulation floor, exterior walls, ceiling: 150 mm
Waterproofing (windproofing) floor, exterior walls, roof
Counter rail +
Vapor barrier floor, walls, ceiling
Antiseptic +
Moisture content of frame wood and finishing materials forced drying
Height inside extension 2. 2 – 2.8 m (depending on the configuration of the house and the wishes of the customer)
Assembly +
Warranty 3 years
Additional works and services
Support-column foundation on cement blocks 200x200x400 mm (one point consists of 4 cement blocks) 3 500 ₽ per point
Tape shallow foundation 200×600 mm (economy) 7 000 ₽ per m
Shallow foundation strip 300×700 mm (standard) 7 500 ₽ per m
Screw pile foundation (all included) 5 000 ₽ for pile
Reinforced concrete pile foundation (all included) 6 000 ₽ for pile
Additional baffle 12 150 ₽ per m
Exterior wall painting (price per coat, customer material) 300 ₽ per m 2
Replacing lining with imitation timber 900 ₽ per m 2
Replacing lining with block house 1 100 ₽ per m 2
Additional double-glazed window 1200×1400 mm
(included: fittings, window sill, drip)
14 800 ₽
Additional paneled door 800×2000 mm 7 500 ₽
Additional metal door 800×2000 mm 22 000 ₽
Additional insulation with boards (50 mm) 550 ₽ per m 2
PVC gutter system 2 100 ₽ per m
Metal gutter system 3 750 ₽ per m
Snow retention system 2 400 ₽ per m
List of regions where we operate

Moscow region, Leningrad region, Belgorod region, Bryansk region, Vladimir region, Vologda region, Voronezh region, Ivanovo region, Kaluga region, Kostroma region, Kursk region, Lipetsk region, Nizhny Novgorod region, Novgorod region, Oryol region, Pskov region region, Republic of Karelia, Ryazan region, Smolensk region, Tambov region, Tver region, Tula region, Yaroslavl region.

Wooden house extension at a low price

Wooden house extension

Not enough space in the house? Are you constantly faced with the problem of where to put things that are rarely used in the household or not used at all?

The way out of this situation is simple. Order an extension to a wooden or any other building at Stroy Kit Pro and enjoy the result!

When the owner of a private household is faced with the need to increase living space, he has two options.

The first of them is building a room of the required dimensions from scratch, but this process is very long, complicated and expensive.

The second, more reasonable way is to solve the problem of shortage of living space by adding an attic, balcony or veranda space.

Modern technologies and materials make it possible to build such wooden or stone structures, which in the future can become not only territories for the economy, but also full-fledged rooms for sleeping or relaxing.

But remember that in order to legitimize such a procedure, you will need to obtain permission to place an extension.

Reliable with us.

Frame extension to the house

The technological process of a wooden frame structure involves the construction of a base made of squared material and horizontal lintels that fix the load-bearing elements. From the inside and outside, this kind of base goes through the process of sheathing the extension with finishing materials – siding, clapboard, timber or boards.

If extension to wooden house is to be used in winter, it is possible to insulate it. This is done by laying a layer of material that is used for thermal insulation between the exterior and interior trim.

For areas with high humidity, it is recommended to take care of reliable waterproofing.

One of the most popular services is an extension to a wooden house. Here are a couple of examples when in just a few days and very inexpensively we are building a frame extension to a turnkey wooden house with a screw foundation and exterior trim with vinyl or plinth siding.

Extension to the house price

Despite the many factors that affect the final price of building a wooden or stone extension, you can get acquainted with the approximate cost of installing an extension to the house in our company.

Description Price per m2 in rubles Timing

Open timber outbuilding

Foundation screw piles

from 12 000

7-10 days

Closed wooden outbuilding

Foundation screw piles

from 24 000

10-14 days

Combined house extension

Foundation screw piles

from 28 000

10-14 days

Two storey building

Foundation screw piles

from 24 000

14-25 days

Brick extension

Foundation from dimensions

from 40 000

14-25 days

Living space extension with extension

Considered improvement option is widely used in private construction with a small number of floors. For an extension, both wooden and monolithic or brick houses are suitable. There is a wide variety of variations here:

  • A terrace attached to the house can be a kind of decoration element. For example, a spacious open-type veranda will certainly turn the inconspicuous facade of the house into a blooming bright garden or a place for tea drinking with the family in the fresh air;
  • An extension to a frame house can be used as a full-fledged living room. It can serve, for example, as a guest room, kitchen or relaxation room;
  • An outbuilding to a wooden or brick building is needed to store, for example, gardening equipment, equipment and supplies that have not been used by family members for a long time, bicycles and scooters. Thus, a lot of free space appears in the living area of ​​​​the house;
  • A comfortable and bright attic extension instead of an attic that collects dust will help to increase the existing living space by 2 times. This is a great option in a limited space.

Employees of Stroy Komplekt Pro will certainly take into account the purpose of the extension under construction and select the most financially advantageous options and materials for work, so that the price of the extension is affordable for the client.

We are second to none in the following jobs.

Positive aspects of the extension to a private house

Among the main advantages of the considered method of expanding the dwelling are:

  • Accessibility;
  • Efficiency of building an extension;
  • Ease of implementation.
  • Low price extension.

In addition, this process will not require temporary “eviction” of households and will provide the owners with a variety of design options to choose from.

Leave a request on our website, and our employees will come to you to clarify all the details and indicate the approximate price for an extension with installation.

The extension, which will be carried out by highly qualified specialists of our company, will help you to realize your ideas to increase the living space of the house.

Frequently Asked Questions

How quickly can your team get to work?

Even during the summer period, our teams begin work on the site within a week from the signing of the contract.

Is it possible to build in the autumn-winter period?

Works related to cement should preferably be carried out at an ambient temperature above +5 degrees. All other works related to the construction of the structure, decoration, installation of windows, as well as the foundation on screw piles, can be carried out in the winter.

Do you work officially?

Our company “Stroy Komplekt Pro” has a full package of permits for construction. We conclude an agreement with all our clients, in which terms and costs are clearly stated. Upon completion, all work performed is accepted by the customer. The guarantee for the work performed by the company is 10 years.

Do you provide your building materials?

We recommend using building materials from our suppliers. All our suppliers have been verified for years. The quality of the offered materials is confirmed by thousands of satisfied customers. In addition, we purchase all materials at large wholesale prices, which has a positive effect on the final price of the extension.

Do you only provide services for the construction of an extension?

We provide a full range of construction services. You do not need to look for other specialists. We build houses, baths, outbuildings, design and lay electricity, provide services for the installation of water supply and sewerage, put in order the adjacent territory and much more. Contact us and get comprehensive information on the service that you need.

Extension to the house, our works

Construction of an extension to the house from aerated concrete turnkey St. Petersburg prices

Owners of suburban housing have the opportunity to increase the useful area of ​​​​the house due to the extension. But to solve this issue, knowledge of the basic rules of construction work is required.

If you want to expand the area of ​​your home without the risk of making mistakes, contact our company. We will build an extension to the house of aerated concrete efficiently and quickly.

Benefits of working with our company

We do it on time or free of charge. Construction is divided into stages with an agreed deadline.

“Turnkey”. All work is done by one company.

Ability to accept payments by installments or on credit.

No hidden fees. The price is final at the stage of the contract.

Quality control is carried out at every stage of building a house by our competent services.

Quality construction work thanks to. We have over 300 successfully completed projects.

Delivery of materials within 200 km from the Ring Road free of charge

Get a free quote

Types of extensions to a house made of aerated concrete

You can expand the usable area and functionality of your cottage through the following types of extensions:

  • terraces;
  • garage;
  • workshop;
  • residential premises.

Prices for construction services

Construction of aerated concrete blocks

“Closed circuit” “Finish”
Aerated concrete 16. 5 thousand rubles/m2 19 thousand rubles/m2
Aerated concrete + decorative plaster 18 thousand rubles/m2 20.5 thousand rubles/m2
Aerated concrete + facing brick 20.5 thousand rubles/m2 23 thousand rubles/m2
(foundation + frame + windows, roof insulation, partitions, stairs) (under draft + electrical wiring, heating, water disposal)
When building a house by our company – the design is free of charge!

Foundation construction

Strip foundation

from 3400 rub/m.p.
Monolithic foundation (slab) from 4200 rub/m2
Screw pile foundation from 3200 rub/piece
Post foundation from 3800 rubles / piece

Roof installation

Installation of vapor barrier

60 rub/m2

Installation of insulation in 1 layer 60 rub/m2
Metal tile from 280 rub/m2
Shingles (bituminous) from 300 rub/m2
Corrugated sheets (Euro slate) from 200 rub/m2
Natural tiles from 400 rub/m2
Seam roof from 350 rub/m2
Decking from 250 rub/m2
Gutter system from 350 rub/m. p.

Floor installation

Underfloor heating from 450 rub/m2
Primer treatment of the screed (moisture protection, dust removal) from 30 rub/m2
Floor joist from 180 rub/m2
Leveling and reinforcing floor beams to level (if already installed) from 80 rub/m2
Installation of subfloors from edged boards from 100 rub/m2
Installation of vapor barrier from 50 rub/m2
Insulation (for 1 layer 50 mm) from 50 rub/m2
Floor plank flooring from 300 rub/m2


Installation of internal electrical panel from 3800 rubles / piece
Plywood sheathing, OSB from 260 rub/m2
Installing the electrical kit inside the sauna from 7000 rubles

Stages of construction of an extension to the house

It is advisable to make an extension of a similar material to a house made of aerated concrete blocks. An important point is the development of the foundation design for the extension. After its calculation, the manufacture of a pit and reinforcement, it is necessary to carry out a mandatory binding of the armored belt of the new building element to the old one. This will help to avoid cracks due to different shrinkage. To do this, the specialists of our company will make end cuts-cuts and combine the reinforcing cages. Then the new foundation can be concreted.

After the supporting base is ready for further use, you can proceed to the construction of the extension walls and other works:

  • Laying the extension box from aerated concrete.
  • Combining roof systems.
  • Insert windows and doors.
  • External and internal finishing.

The advantage of aerated concrete for the construction of an extension

Aerated concrete is a unique building material. It is safe for health, has good thermal insulation and strength properties. With it, you can create an extension of any configuration. The main thing is to know the nuances and be able to use them in practice. We will help build an extension and combine it with an existing building. The foundation, walls and roof will be a reliable continuation of these elements of your cottage.

Construction of an aerated concrete house extension from our company is an effective way to expand the usable area of ​​your cottage. We will carry out such work and help to formalize the changes in the relevant authorities.

Frequently asked questions about the construction of aerated concrete blocks

How thick should the walls be in an aerated concrete house?

– The minimum thickness of a load-bearing wall according to building codes is 250 mm, even if it is a summer house. The smaller wall thickness is not able to withstand the loads of the roof and the influence of external factors such as wind. For year-round living in the house, it must be equipped with a heating system, facade insulation and ventilation. For internal partitions, smaller blocks are used, their thickness is 100mm.

What is the most cost-effective option for external finishing of aerated concrete walls?

– Finishing a house made of aerated concrete should be taken seriously. Aerated concrete material with high vapor permeability. Due to the temperature difference (inside and outside), condensation forms in it. Therefore, for exterior decoration, it is worth choosing a material that helps reduce vapor permeability. The most budget option for finishing is staining. However, the walls in this case should be close to a perfectly flat state. You can reduce the cost of painting by using inexpensive facade putty. To give it the desired color, add a water-based color scheme. The most rational finishing option is a ventilated facade using sheet finishing materials (block house, siding, etc.). The most expensive is facing brick, it is also the most durable and reliable.

How to reduce the cost of building with aerated concrete?

-To reduce the cost of construction, you can abandon the full-fledged second floor and make an attic. To save the budget, it is better to choose a house shape close to a cube, with a minimum number of protrusions and complex shapes, to abandon bay windows and balconies. A large number of windows and a minimum of internal partitions also reduce the cost of building from aerated concrete

What area of ​​a house made of aerated concrete would be optimal?

Researchers believe that an area of ​​30 square meters per person is the most comfortable option. However, when designing a house, first of all, the construction budget is taken into account. The size of the plot also matters, its improvement is important, as is the comfort inside the house. If the site is not large, it makes sense to think about the second floor or attic.

Does the house need a basement?

To answer this question, first of all, it is necessary to carry out geological surveys. With a high level of groundwater, the construction of a basement floor will be unreasonably expensive. But if the soil allows, then building a basement will be appropriate when you want to: make a workshop or a room for storing inventory, make a pool or sauna. If the site is on a slope, such a basement is formed naturally. During construction, it can be equipped and find useful use for it.

Which roof to choose for a house made of aerated concrete?

The main recommendations for the construction of a roof for a house made of aerated concrete are as follows:

  • – it must be pitched;
  • – the edges should be as long as possible so that less moisture gets on the facade;
  • – it is better to abandon heavy materials (natural tiles) in order to reduce the load on load-bearing walls;
  • – tightness must be observed so that moisture does not seep inside.

When choosing materials, it is better to turn to classic sheet metal. The most budgetary, but at the same time reliable and durable – slate (asbestos-cement sheet). However, such a sheet cannot be mounted independently due to its weight and fragility; it periodically requires treatment from the fungus. A very practical material is bituminous slate (ondulin). It is easy to install and affordable. Unlike metal tiles, it is silent.

Do you offer installment payments or credit?

Yes, when ordering construction in our company, you can use interest-free installments. We also cooperate with banks, where you can arrange construction on credit on favorable terms.

Which foundation is suitable for an aerated concrete house?

Since aerated concrete has a relatively small weight, you can save the budget for the construction of the foundation. The main nuance is the rigidity of the base, since cracks can occur during its subsidence. Before choosing a foundation, it is necessary to conduct geological surveys and determine the type of soil. If the soil is heaving or sandy, that is, it is in motion, then only a strip foundation will do. If the groundwater level is high, then it is better to opt for a monolithic slab. But if the soil allows, a columnar foundation will save a lot of money and time compared to previous options.

Do-it-yourself extension from gas block (aerated concrete)

The work process consists of the following steps:

First, you should mark the ground, observing the squareness of the corners and the parallelism of the lines.
Then dig a trench along it, arrange a sand or gravel cushion with a layer of 20-30 cm and compact it.
After that, you need to erect the formwork, and mark on it from the inside the upper level of pouring concrete.
Lay with roofing felt or roofing paper for waterproofing.
Reinforcement should be done with a 12 mm rod, for vertical clamps – 8 mm, for horizontal clamps – 6 mm. It is better to connect with a knitting wire, since welding is less durable.
The gas block extension has a small foundation, so concrete can be made independently (1 part of cement, 3 parts of sand, 5 parts of crushed stone) in a concrete mixer. At the same time, take into account that the pouring should be as fast as possible and from different angles (stretching the solution is unacceptable). If the concrete is custom – one-stage.
Seal the solution with a bayonet method and cover with a film to reduce moisture loss. 2 times a day it needs to be removed and watered the foundation with water for several days.
At a temperature of 20 degrees, formwork can be removed after 8-10 days.
Complete drying of the base and its readiness for laying the wall gas block will come after a month.

Which gas block to choose for the walls of the extension

In our climatic zone in Ukraine, it is extremely important that the building is warm. Therefore, you need to pay due attention to which gas block to buy. If the aerated concrete extension is heated, then we recommend buying a gas block with dimensions of 300x200x600, 375x200x600 or 400x200x600 mm. Where the thickness of the gas block is 300, 375 and 400 mm, respectively. Please note that the gas block with a thickness of 375 mm and 400 mm does not require external wall insulation with mineral wool or foam. A gas block with a thickness of 300 mm will still have to be insulated.

You also need to take into account the density of the gas block. Ukrainian plants for the production of aerated concrete produce blocks with a density of D300 (D300), D400 (D400) D500 (D500).

The density of a gas block depends on the number of bubbles in the block. The lower the density, the aerated concrete block is warmer, but less durable.


  • 2. gas block D400 (D400) (produced by the manufacturer UDK (yudk) in the Dnieper) is the golden mean of strength and heat preservation.
    3. gas block D500 (D500) (produced by the manufacturer XSM (HETTEN) in Kharkov) is the most durable, but the least warm

TIP: If you want an extension made of aerated concrete (aerated concrete) to be warm, use an aerated concrete block with a thickness of 375-400 mm and a density of D400

Before proceeding with the construction of the extension, you need to buy aerated concrete. But the question often arises – how many aerated concrete blocks are needed for an aerated concrete extension. Its quantity is easier to calculate in pieces, based on the surface area, with the exception of doors and window openings, than in cubic capacity. It is very easy to calculate the number of required aerated concrete blocks for an extension from an aerated concrete block. In 1 m2 of the wall – 8.33 pieces of wall gas block.

Example: You want to build an extension 6 by 4 meters and 3 meters high.

1. You need to find the total number of square meters. To do this, add the length of 3 walls. In our case, with an example of 6 + 4 + 4 \u003d 14 linear meters.

We multiply by the height of the aerated concrete extension 14×3=42 m2. We got the total area of ​​the extension – 42m2.

2. Subtract the total area of ​​openings from the total area of ​​the aerated concrete extension (For example, the area of ​​windows and doors is 6m2). 42-6m2=36 m2

3. Next, you need to understand how many gas silicate blocks are in 1 m2. We calculate the area of ​​one block: 0.2 (height of the gas block) x 0.6 (length of the gas block) \u003d 0.12 m2. For one m2, we get: 1: 0.12 = 8.33 pieces of gas block (foam block).

4. Last 36 m2 x 8.33 pcs = 299.8 pcs.

Tip: When calculating an aerated concrete extension, add 3-5% to the required amount for undercutting and cutting.

The price of a gas block is much lower than a brick or timber, so the total cost of construction will not be significantly affected.
Before erecting walls, the foundation should be treated with bituminous mastic for waterproofing. And also prepare aerated concrete blocks – eliminate chips and irregularities, remove burrs with a planer.

Aerated concrete assembly

First row . Laying is carried out on cement mortar, starting from the corner. For greater reliability, you can drive reinforcement bars (8 mm) into the foundation so that they pass between the blocks. The thickness of the seam of laying the gas block on cement should not exceed 15 mm.

Second and subsequent rows . They are placed with an offset of 1/2 the length of the product or a little less. With perfectly aligned blocks, you can put them on glue, while its thickness is up to 5 mm, after leveling with a notched trowel and installing the product, it will decrease to 3 mm. Glue for the gas block retains its characteristics for 90-120 minutes.
You can correct the blocks after laying the first 10-12 minutes.
For better adhesion, the surface of the products should be moistened.
The last row. Metal studs are mounted in it for the subsequent installation of a Mauerlat (truss system).
Shrinkage of gas blocks is provided for 3 mm per 1 m of height, so you can start finishing after 1 month.

Roof and roof

Usually, a shed roof is made at the extension with an angle of inclination of 35-45 degrees for independent snowmelt. Install floor beams. Rafters are attached to the Mauerlat from wooden beams in increments of 60-90 cm, then a crate of boards and a roof. It must match the main structure. If desired, the roof of the aerated concrete extension can be insulated with glass wool or foam.
Aerated concrete is an environmentally friendly and frost-resistant material. It saves heat well, is easy to process and install, is strong and durable, has low weight and is resistant to fire. An extension of aerated concrete blocks is perhaps the best option in the price range.

Extensions to the house: terraces, verandas, vestibules. Price.

BRUS.RU offers services for the construction of extensions to the house: terraces, porches, insulated verandas, vestibules.


The cost of building a terrace is 18,000 rubles. per m 2

Equipment description




timber 40×150 mm with a step of not more than 600 mm

Finished floors

grooved floorboard 36 mm


planed timber 150×150 mm


wooden; baluster or plank (optional)

Rafter system

Edged board 40×100 mm with a step of no more than 600 mm. Lathing from edged board 18-22 mm.

Ceiling (finish)

“B” class lining


ondulin or metal tile

Counter rail


Vapor barrier

under-roof (class “A”)

Terrace steps


Material moisture

all wooden elements of the terrace – forced drying


3 years

Verandas (closed type), vestibules

The cost of building a frame veranda or vestibule is 28,000 rubles. per m 2

Equipment description




timber 40×150 mm with a step of not more than 600 mm

Sub floors

edged board 18-22 mm


Racks from a board 40×100 mm with a step of no more than 600 mm. Jaws from a board 40×100 mm.

Rafter system

Edged board 40×100 mm with a step of no more than 600 mm. Lathing from edged board 18-22 mm.


ondulin or metal tile

Counter rail


Vapor barrier

floor, ceiling, walls: on both sides of the insulation (class “AB”) + roofing (class “A”)


floors, ceilings, walls; insulation layer 100 mm Rockwool Light Butts

Finishing (walls on both sides, ceilings)

“B” class lining

Internal corners and joints (finishing)

wooden plinth


wooden double, with window sills and sills; casing on both sides

Entrance door

metal, trim on both sides

Finished floors

grooved floorboard 36 mm

Steps at the entrance to the veranda or vestibule


Material moisture

all wooden elements of the veranda or vestibule – forced drying


3 years

Extension price list in popular sizes


Terrace or porch

Closed porch or vestibule

1. 5×6 m

RUB 162,000

RUB 252,000

1.5 x 7 m

RUB 189,000

RUB 294,000

1.5×8 m

216 000 rubles

RUB 336,000

1.5×9 m

243 000 rub.

RUB 378,000

1.5×10 m

270 000 rub.

420 000 rubles

1.5×11 m

297 000 rub.

462,000 rubles

1.5×12 m

RUB 324,000

RUB 504,000

2×5 m

RUB 180,000

280 000 rub.

2×6 m

216 000 rubles

RUB 336,000

2×7 m

252 000

RUB 392,000

2×8 m

288 000 rub.

448 000 rubles

2×9 m

RUB 324,000

RUB 504,000

2×10 m

RUB 360,000

RUB 560,000

2×11 m

RUB 396,000

RUB 616,000

2×12 m

432,000 rubles

RUB 672,000

3×3 m

RUB 162,000

RUB 252,000

3×4 m

216 000 rubles

RUB 336,000

3×5 m

270 000 rub.

420 000 rubles

3×6 m

RUB 324,000

RUB 504,000

3×7 m

RUB 378,000

RUB 588,000

3×8 m

432,000 rubles

RUB 672,000

3×9 m

486 000 rubles

RUB 756,000

3×10 m

RUB 540,000

840 000 rubles

3×11 m

RUB 594,000

924 000 rub.

3×12 m

RUB 648,000

RUB 1,008,000

4×4 m

288 000 rub.

448 000 rubles

4×5 m

RUB 360,000

RUB 560,000

4×6 m

432,000 rubles

RUB 672,000




Cement block foundation

RUB 3,000 for 1 point

Screw pile foundation

RUB 6,250 for 1 pile 2.5 m

Reinforced concrete pile foundation

RUB 7,250 for 1 pile

Strip foundation 300 mm (width) x 700 mm (height)

7 300 rubles/linear m

Replacement of lining for exterior finishing with block house

1,050 rubles/m 2

Exterior lining replacement with siding

1,300 rubles/m 2

Replacing lining for exterior/interior finishing with imitation timber

950 rub/m 2

Additional layer of insulation 50 mm Rockwool

650 rubles/m 2

Installation of PVC gutter system

1 750 rubles/linear m

Installation of a metal gutter system

3 400 rubles/linear m

Mounting snow guards

2,025 rubles/linear m

Additional wooden window 1000×1200 mm

RUB 6,000

Replacing a wooden window with a plastic one 1000×1200 mm

RUB 9,500

Painting of exterior walls with Pinotex (Contractor’s Pinotex)

600 rubles/m 2

Delivery of materials to your site from Pestovo (Novgorod region)

75 rubles/km

Call the hotline 8 (800) 775-95-85 (toll-free in Russia)

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Frame extension to a frame house – expanding!

  • What is a frame extension?
  • Benefits of Canadian-style frame extensions
  • About types of extensions
  • Construction phases
  • Q&A
  • Examples of house projects and construction cost calculation

If there are objective reasons for expanding your home, or you simply decided to increase the living space of your house for personal reasons, the most optimal and acceptable option is a frame extension to the house. After all, the technology of building frame houses, as well as other structures using Canadian technology, is fast, high-quality and, importantly, inexpensive!

Indeed, this solution to the problem is quite popular, because it will take a minimum of both money and time to improve housing!

What is a frame extension?

An extension to the house using frame technology is a strong, reliable frame, finished inside and out, insulated on all sides. The construction of the extension frame is light, reliable and functional. If you have experience in building houses or structures using frame technology, you can build an extension yourself. If there is no such experience, then it is better to turn to professionals.

Advantages of frame outbuildings built using Canadian technology:

  1. A frame extension is as reliable as a frame house using Canadian technology, the reviews of those who have already used this option for housing expansion confirm what has been said. Such construction has been time-tested: after all, even the ancient Indian tribes on one side of the globe, and the Eskimos on the other, built frame dwellings.
  2. Thanks to this method of pre-fabricated construction, you can expand as you like and any kind of premises – houses, cottages, summer cottages.
  3. In addition, the frame extension to the house will serve not only as additional living space, it will provide the house with excellent thermal insulation. Consequently, in the cold season, a house, cottage or small cottage will heat up faster. And the extension will work on the principle of a thermos – after the room is completely heated, it will maintain the temperature for another 7 hours.
  4. Another significant plus of the frame extension is that finishing can be done immediately after the completion of construction work. Any frame construction does not shrink.
  5. Such a structure can be disassembled as a constructor. This fact will especially please those who love change. From the details of the extension, you can assemble new premises – utility blocks, garages, and so on.

For the extension, any finishing materials are suitable. If the main unit was built a very long time ago, many years ago, experts recommend using modern finishing methods. Their successful combination is a guarantee that the frame extension to the wooden house will ideally “fit” into the architecture of the building.

Types of extensions

Depending on the design, an extension to a capital structure can be of one of the following types:

  • Frame-panel. A simple technology in which SIP panels act as walls. They already have insulation in their design, so there is no need to insulate the frame extension to the house. Interpanel seams are quite easy to putty, which greatly simplifies and speeds up the process of interior decoration of the extension.
  • Frame-frame. The technology is similar to the previous one, however, instead of SIP panels, it involves the use of OSB sheets. They are mounted on frame racks. The downside is that you will have to additionally insulate the building, and inside make plasterboard lining.

We invite you to consider the process of building a frame-type extension in more detail.

Construction steps

The construction of a frame veranda-extension to the house is a non-trivial process that requires patience, attentiveness and great strength from the performers. If you doubt that you will be able to finish what you started, it is better to entrust this work to professionals who know their job.

Foundation installation

As a rule, an extension is erected much later than the completion of the construction of the main house. If this is the case in your case, you will have to make a separate foundation and connect it to the base of the building using embedded reinforcement. You have a choice of three basic foundation types:

  • Tape. A versatile option that is equally well suited for both light extensions and massive frames. Cons: Relatively high construction cost.
  • Columnar. Alternative option for lightweight structures. It is cheap, but imposes a restriction on the arrangement of the basement, but it is simple and quick to manufacture.
  • Pile. Used to install massive and large outbuildings. It is built from piles that are driven deep into the ground and provide high structural stability.

The type of foundation for the extension must be the same as the foundation on which the building stands. When choosing the type of foundation, be sure to consider the characteristics of the soil on the site. If the soil is “strong”, an extension to a frame house on screw piles or on a strip foundation will not be the best choice, while a columnar foundation will suit these conditions just in time.

Trim assembly

At the second stage, the strapping beam is mounted. Since annexes rarely house living quarters, you can save money and use thinner timber and vertical posts than for a house – 10 cm instead of 20 recommended for heated living rooms.

Frame installation

The frame can be assembled in one of two available ways. The first is the arrangement of external walls with a series of vertical posts made of wooden beams, which are connected to each other with lintels. The heads of the racks are necessarily attached to the upper strapping beam, on which the ceiling and the roof of the facility will be formed in the future.

The second frame assembly method is used in the case of the construction of large outbuildings. In this situation, it is not necessary to assemble the outer frame in the above-described cellular method. Instead, only corner posts are equipped, then the upper trim is laid, and SIP panels are installed in the gaps between the timber. Next, the beams of the interfloor overlap are sewn.

Roof assembly

Roofing can take up to half of the total construction time of an extension. This process can be accelerated, for example, by choosing a simple roof scheme. One of the easiest options in terms of implementation is a gable roof, coaxial to the roof of the main building. Their articulation will not take much time and effort, if you plan in advance the height of the building to be 60-70 cm less than the height of the house – the roof will rest against the pediment.

Regardless of the type and quality of the foundation, due to the large difference in the load that the house and the frame extension create on their foundations, there is always some risk of their movement relative to each other. In this regard, it is not recommended to use a rigid adjoining of the building to the building. Instead, you should resort to a more flexible connection, similar to the tongue and groove. For proper docking of the extension to the house, fix two beams on the wall of the building. Between them, install one vertical beam connected to the extension. Thus, a movable contact will be obtained, which does not deform even with a fairly noticeable mutual shift of the buildings. Instead of a wooden beam, you can take a metal or bolted swivel.

A separate issue is the docking of the roof of the extension with the roof of the house, one contact of the walls is not enough here. For a reliable and deformation-resistant contact, dock the rafters at one end with the upper trim of the frame, and connect the other end with the truss system of the building. The crate under the roof is installed so that the junction of the old and new roof is between it.


Question: what tools are needed for construction?

Answer: to make a frame veranda-extension to the house, you will need an electric saw, a tape measure, a hacksaw, a hammer, a building level, a screwdriver, pliers, a screwdriver and a cutter. For some types of work, you will need the help of another person.

Question: what foundation should I choose for the extension?

Answer: the ideal option is when the house and the extension are installed on a single foundation. If the moment is missed and you want to make a massive and large addition to the building, it is better to choose an extension to the frame house on screw piles. For light objects, columnar is suitable.

Question: How to properly connect an extension and a house?

Answer: for docking an extension to the house, we recommend using a movable connection that does not deform if the construction objects suddenly begin to move relative to each other. One of the options: a tongue-and-groove joint assembled from three vertical beams.

Question: how to join the roofs of adjacent buildings?

Answer: docking the roof of the extension with the roof of the house is carried out as follows: the rafters at one end are connected to the upper trim of the frame, and at the other they are mated with the truss system of the house. The stage cannot be skipped, since the roof connection must be movable.

Question: What material should be used to insulate the extension?

Answer: regarding the insulation of a frame extension to the house, all the same recommendations and rules apply as in the case of thermal insulation of a frame residential building. Wood sawdust, ecowool, mineral and basalt slabs, extruded polystyrene foam and others are well suited.

Question: Is it necessary to register an extension?

Answer: yes, the frame extension needs to be legalized, and it is advisable to think about it even before the start of construction work. At the initial stage, the project can be legalized by administrative means, but if the object has already been built, you will have to go through a more difficult path through the courts.

Check out the plans of houses and calculate the cost of construction

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