How much do building extensions cost: House Extension Cost | Project Estimates

House extension costs | CR Design Services

One of the most frequently asked questions that pop up with clients is ‘How much will my house extension cost?’ The only way that we can give a clear answer is to assess the project and prepare drawings and tender documents. You can then ask builders to put in their cost proposals.

Another way of working out a price is to look at the amount of space involved and what needs doing. By using industry standard costs we can estimate total costs for a project. This lets clients know roughly how much money they need to set aside, even before they have applied for planning permission, building regulations or had tender drawings prepared.

We have prepared a list below of some average costs for extensions. Here you can see prices for London/South East and the rest of the UK as prices vary considerably due to location.

Description London and South East Rest of the UK
Single storey extension £1900 – £3000 per m² £1800 – £2600 per m²
Double storey extension Cost of single storey extension plus 50% Cost of single storey extension plus 50%
Loft conversion with roof lights (Based on 4 x 5m floor size with 2 roof lights) £22000 – £25000 £20000 – £24000
Loft conversion with roof lights (Based on 6 x 5m floor size with 4 roof lights) £31000 – £35000 £26000 – £30000
Loft conversion with dormer (Based on 4 x 5m floor size with 1 roof dormer and 1 roof light) £33000 – £36000 £30000 – £34000
Loft conversion with dormer (Based on 6 x 5m floor size with 1 roof dormer and 1 roof light) £42000 – £46000 £39000 – £44000
Hip to Gable extension £30000 – £45000 £45000 – £65000

As can be seen, building costs vary according to size, design and specification. Labour takes up about 40% of the cost. Let’s take a look at the four key factors that can influence the cost of your building works:


New extensions are normally costed according to pounds per square metre. If you look at the chart above, you can see the difference between the loft conversions with different floor sizes. The larger the floor area, the higher the final price.


The design of your extension has a big impact upon the final price. Most clients come to us with a pretty good idea of what their new extension will look like, but we can take their design and suggest improvements and alternatives. Working with your builder, we will share details of the planning permission and building regulations drawings, along with our structural specification. This allows your builder to get a full understanding of the project and give an accurate cost. It avoids you being hit with unexpected charges later on as once a fixed proposal is in place, any changes will be charged as extras by your builder.


The provision of a detailed specification shows the builder exactly what materials and labour are required. This avoids any grey areas during the project build. This can include literally hundreds of specification and design options with each one having an effect upon costs. The higher the specification, the more things will cost. If you make changes after the specification has been created, not only will your house extension costs escalate but construction delays will likely occur. We can assist you with the choice of items, no matter the type of extension you are having built.

There are so many things that can influence the cost of your house extension. Here are just a few of them:

  • Bricks, cladding, roof tiles, doors/windows, gutters
  • Decoration, plastering, flooring, tiling, lighting
  • External and internal walls, roof, insulation
  • Foundations, drains, floor slab
  • Patios, drives, paths, landscaping
  • Plumbing, heating, electrics, stairs, ventilation, internal doors
  • Site investigation, clearance, demolition, new utilities
  • Site management, scaffolding

If you are having a kitchen or bathroom installed, the fittings for this will need to be taken into account. Unforeseen costs can be things such as poor ground or structural conditions; sometimes these do not show themselves until work begins.

4. Project management

You may find that your builder will take care of the project management on your behalf and that this is included in the proposal. This saves you a good degree of time and effort as you don’t need to get involved at all; simply step back and let the work continue. The best technique is one that applies a straightforward hands-on approach that includes constant cost and quality control. At the same time, the project manager needs to ensure that your project follows the scheduled programme towards the targeted completion date.

Additional costs

In addition to the costs above, remember to include planning application and building regulation fees. There will also be our fees for the design and preparation of drawings, specification and structural design of the project.
No two extensions are ever the same. The details that we have given above can however be used as a rough guide, particularly if you are trying to organise funding. Once you decide to proceed, we can help you from initial design stage, planning application drawings, building control drawings and specification, structural design and we can also prepare, submit and manage the applications with your local authority. Contact us for more details.

Matching with your existing building

Design affects the inside and outside of your extension. The best are seamless, blending effortlessly with the rest of your home. Whilst this can be difficult when it comes to matching materials, it is well worth the effort and something that we always aim for, using reclaimed materials where possible. Alternatively, if you want a deliberate contrast between old and new, we can do that too. For instance, some clients with period homes have asked us to add on very contemporary extensions that stand out for a purpose. When done well this looks superb.

How important is design?

Good design is everything. A well-designed house extension can completely change even the most basic of homes. Maximising floor space and adding in elegant features will increase the value of your property. At the same time, you will find living in the space so much more enjoyable and efficient. If you compare house extension costs to the cost of moving home, then making your present home more attractive makes so much sense. When designed correctly, your new extension can create the perfect space to suit your needs. Contact us to start your project today.

Building Costs for Construction

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House Extension Costshouseext2022-04-26T04:49:56+00:00

So, you have decided to get the much-awaited house extension for your place. Regardless of the reason, the cost is the essential factor determining everything. After all, you wouldn’t want to run out of funds or burn a hole in your pocket as you get the job done. Therefore, it is pivotal for you to learn about house extension costs.

To help you gain more clarity, here are some answers to common questions you will encounter:

There’s a quick answer for you – use the home extension costs calculator. It is frequently managed with up to date information to help you get an accurate idea about the costs. Indeed, it can vary, but slightly, according to the change in the economy. However, if you don’t want to go through the trouble of estimating everything by yourself, it is a good idea to use the home extension costs calculator.

Perhaps you don’t want to use the calculator. That’s understandable if you want to do the old-school things. Different factors determine the overall home extension costs. Here is a glance at some of these aspects:

  • The building elements like debris removal, siding replacement, type of roof, windows, and doors
  • Your location. Even in Australia, different areas have varying costs.
  • The kind of extension project and the scale from a single room extension to a second story extension.
  • The time it will take to finish the project.
  • The material required to complete the project.
  • Quality of the material.
  • Professionals that you will hire.
  • Any additional damage, repair, or unforeseeable emergency funds.

Let’s not forget the cost of getting a permit for an extension. These are just factors that make up for the overall quote for the building extension costs. If you can find answers to these questions, you will have a reasonable estimate of the expenses.

The average extension costs per square metre are around $2,000 to $4,000, roughly. You will also have to consider the hourly rates of hiring a professional, like a carpenter. That is approximately $40 to $60, depending on location in Australia.

Correlatively, the ground floor extensions are cost-effective. Meanwhile, second story extension costs twice as much as the ground floor. After all, you will have to hire professionals to draw out the map, and the task requires professionals.

Where or how can you get the cheapest house extension costs in Australia? To be fair, it is not that easy. However, there are some tips that can help you cut down the cost:

  • Try to get a simple extension with a basic design.
  • Don’t invest in interior designers or other similar services.
  • Stick to basic materials that are readily available in your area.

As mentioned earlier, a double story extension costs more than a ground-level or single-level extension. By that rule, you could have affordable renovation extension costs. It is when you renovate a room and extend it slightly in size—for instance, getting one side of the room elongated by moving the walls further.

It is generally easier to get a permit for these too. But it only works if you have ground-level construction.

Now that you have a good idea about house extension costs in Australia, it is expected that you will want to look for cheaper alternatives. You already received a couple of tips above to help you with cost-effective methods. However, what if you’re looking to enhance the value of your property?

Here is a quick overview of ideas that can enhance the value of your place:

  • Extra Room Or Bedroom: +20%
  • Kitchen Space Extension: +10-20%
  • Loft Conversion: Around 15% increment in value.
  • Living Space Extension: 10-15% increase.
  • Extra Bathroom: 5-15%, depending on whether it is attached to a room or a standalone.

These costs are similar to the owner builder extension costs. You already received the idea of a cost per metre square. Now, you will just have to multiply accordingly. Still, for a basic room, you can expect anywhere around $30,000 for a complete extension.

Comparatively, if you add a bathroom, you can save around 20-30% of the cost. You can add a bathroom for about $20,000. However, if it is a bigger or more luxurious bathroom, the price can go above $30,000.

An ensuite adds value from anywhere between 5 to 10%. Typically, it is around 5%, but the quality and size of the ensuite can also impact its value. However, as it is a part of the room, it will always add less value. Either way, it is still cost-effective in terms of building extension costs.

You will have to reach out to the professional and get an idea. There is an option to either shrink the size of the room or provide an extension. Either way, you should be able to add a bathroom. There are specific permits, but it is easier to get them than a full-fledged extension.

From the overall evaluation of home extension costs, you can quickly determine that adding a single room would enhance the house’s value. However, if you can invest in a completely new floor or story, you will witness a more significant increment. But remember a double story extension costs twice as much as the average extension.

There is also an idea of the granny flats that you can use to enhance the value of your house. These are cost-effective and provide a significant return on investment. They are pretty popular in Australia for multiple uses.

We hope you found all the answers to various questions regarding a home extension project. If still not sure, you can get a good idea by using a home extension costs calculator.

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Houses from profiled timber with a veranda from SK Pestovo: projects, turnkey construction and shrinkage, prices

SK Pestovo builds houses from timber with a veranda according to standard designs from the catalog and our own drawings of customers. Explore the solutions below and choose the one that suits you best.


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Timber houses with a veranda: comfort and outdoors

Owners of private country houses enjoy a quiet life surrounded by nature away from the bustle of the city. In order to fully experience all the benefits of being in such a favorable atmosphere, one should not forget about such an important component of the building as the veranda. An open extension to the house not only gives the building more functionality, but also allows you to make your pastime in it pleasant and varied. Timber houses with a veranda from the manufacturer SK Pestovo are a practical and stylish solution for those who appreciate modern design and like to invite guests.

Reasons for building

The construction of houses with verandas from profiled timber on a turn-key basis and for shrinkage has its own subtleties and requires competent and most accurate calculations in the design. However, despite the apparent difficulties, many choose just this option – and there are reasons for this:

  • Aesthetics. The extension to the house of a covered area gives the building an elegant look and solidity, making it larger and more harmonious.
  • Versatility. The veranda can be used as a dining room, a playroom for children, a place to store various things, and even as an office.
  • An opportunity to save money. Adding a full-fledged residential wing to the house will cost more than building a beautiful insulated veranda.
  • Comfortable outdoor activities. A covered extension will allow you to gather friends and enjoy a rewarding holiday at any time of the year.

Today it is possible to build an open or glazed, insulated or summer extension to the building. In our catalog of house projects with a timber veranda, you can find a solution that suits you completely.

Construction of a veranda

Selection of high-quality wood, calculation and laying of a strip foundation, correct construction of a frame and installation of a roof – these are just some of the features of building houses from timber with verandas from Pestovo. We offer our projects and are ready to implement them according to your needs and wishes – our catalog contains several dozen options.

Our company not only builds with quality wood, but pays special attention to the needs of customers. Here you can buy a house from a bar with a veranda inexpensively – and be sure that the work will be completed on time and for the price agreed in advance. A stylish house with a cozy modern extension at a reasonable price is a great option for living or vacationing in the country!

Frame extension to the house – to a wooden, to a brick building

Consultations / ordering services: 8 (812) 988-20-58

As a rule, a frame extension to a house is a good option in order to transform the building, significantly expand its area, and also acquire additional useful space. The most important thing is to carefully consider the construction plan and design the structure in accordance with its intended purpose.

So that the frame extension to the house does not transform during subsequent operation, it is necessary to think over every nuance of the structure at the planning stage. Namely, the purpose is initially determined. There are several good options.

  • Additional plan room. According to statistics, such rooms are needed for small houses with 1-2 rooms inside. Naturally, if the room is residential, then it is necessary to perform waterproofing and thermal insulation, since otherwise the installed heating will not be effective.
  • Kitchen or toilet. For such premises, it is especially important to correctly plan engineering communications, and this is done before the installation of the foundation. Those places where water or sewer pipes will pass through the base of the house must be perfectly insulated to prevent freezing, the formation of fungus and mold.
  • It can also be a veranda, which is a light construction of an open and glazed type. It is used for recreation in the summer and this building should not be heated. The design itself is simple to the point of impossibility, since there are enough walls and roofs on supports. The main thing is that the scale of the structure is combined with the parameters of the building.

10-year workmanship guarantee

from 4,900

House lifting

from 65 300

Foundation replacement

from 48 600

House reconstruction

Naturally, for the construction, you need to choose a foundation and the best option would be just a pile-screw, which has a lot of advantages in the form of:

  • Stability on different ground;
  • Adaptation to different regions;
  • Durability;
  • Efficiency of installation;
  • Stability on difficult terrain;
  • Ability to carry out installation regardless of the season;
  • Strength;
  • Reliability.

The most important thing is that the installation of the frame extension to the house is carried out by experienced specialists who are able to ensure compliance with all the requirements and standards of GOST.