Double extension cost: Guide to costs and planning permission for a two storey extension

Guide to costs and planning permission for a two storey extension

Two storey extension above by Daniel, an architect on Design for Me. View his full profile and shortlist him for your project here


A two storey extension can be a cost effective way of gaining maximum floorspace for your property, without eating too much into your garden. It will also mean that your house isn’t bottom heavy, which can be an issue with some large single storey extension projects where they have a huge living space but a lack of sleeping accommodation above. This short guide to two storey extensions will cover the two most important points to get you started: Do you need planning permission for a two storey extension? and How much does a two storey extension cost?

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How much does a double storey extension cost? 


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

As a basic rule of thumb, a two storey extension will cost around 50% more than a single storey extension. Read about extension costs per square metre in our guide here. Based on this guide a (3x6m) two storey extension would be upwards of £60,000 for the basic build cost.

  • Add on 10-15% for professional fees (architect, planning application, building regs, structural engineer) (£6,750 at 15%)
  • VAT (£12,000)

Double storey house extension cost = upwards of £81,000+

Please note this does not include kitchens or bathrooms, and applies to most areas in the UK. Costs in London and SE can be considerably higher.  

For more detail, read our blog on calculating your a house extension cost here.


Do I need planning permission for a two storey extension?

Two storey extensions do not require planning permission, if they fall within permitted development guidelines described below.


How big can I build a two storey extension without planning permission?

  • MAXIMUM HEIGHT: Firstly the eaves and pitch heights must be no higher than those of the existing house. However, if the building is within two metres of a boundary, the overall maximum eaves height is restricted to 3m. The roof pitch should match the existing house as much as reasonable practicable.
  • FOOTPRINT: Under permitted development rules, you can extend up to three metres from the original house* but it must be more than seven metres from the rear boundary (opposite the rear wall). Any extensions to the original house*, sheds or outbuildings should not exceed more than 50% of the total area of land around the house.
  • MATERIALS: The materials used should be similar in appearance to that of the existing house.
  • LOCATION: Two storey extensions to the side or front of the original house are not permitted development.
  • OTHER: No verandas, balconies would be allowed without planning permission. Any upper floor window in a side elevation must be obscured glazing and non-opening (unless its more than 1.7m from floor level internally).

*original house means as it was built or as it stood on 1st July 1948.


There are some specific restrictions regarding your particular property that you will need to check too:

1. Is your property a house?

Flats, maisonettes or any other type of buildings do not have permitted development rights, so you won’t be able to build your extension without getting full planning permission. Also, be aware that if your property has undergone a change of use or has been converted into a house in the past, it may not enjoy permitted development rights.


2. Is your house, or any buildings contained within the boundary, listed?

If so, you will need to contact your local council as other permissions may be required e.g. listed building consent. This often requires more detail than a typical planning application.


3. Is your house in a conservation area or other ‘designated land’

This includes National Parks, areas of Outstanding Natural Beauty, the Norfolk or Suffolk Broads and World Heritage Sites. If so, you will not be able to build your two storey extension without full planning permission.


Note: The above advice relates to England, and policy in Wales may be different.


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filed under Advice and tips, Extensions, Legal Considerations.

What is The Cost of a Two Storey Extension?

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(Image credit: Martin Gardner)

If you have questions about the cost of a two storey extension, we’re here to help. One of the most important elements of building an extension is effective budgeting as this will ensure the project runs smoothly and is delivered on time. 

Although the costs of a single storey extension and that of a double storey extension don’t vary too hugely, there are differences that it is worth bearing in mind.

Two storey extensions tend to require careful design planning in order to work well with an existing house and are also much more likely than single storey extensions to require planning permission. They will also require you to reconfigure your first floor layout in many cases, all of which can add to costs. However, they tend to be more cost-effective per m2 as compared to single storey extensions.

Here, we take a look at the cost of a two storey extension and explain how these costs might compared to those associated with other types of extensions.

What Factors Affect the Cost of a Two Storey Extension?

Although it is possible to give a rough figure for what double storey extensions are likely to cost, there are obviously a few variables that will affect the price you are quoted. These include:

  • The size of your extension
  • How complex the design is
  • The quality you are aiming for
  • How much of a hands-on role you are prepared to take on
  • Who you get to design your extension
  • The amount and type of glazing you specify
  • What the new extension is for — bedroom, bathroom, kitchen etc.
  • Where in the country you are building

The cost of a two storey extension will very much depend on its specification and extra features. This stunning double extension, designed by Tim Offer Architects, to a barn conversion features a zinc roof and lots of glazing.   (Image credit: Matthew Smith)

How Much Does a Two Storey Extension Cost in 2022?

So, just how much does an extension cost these days? Up until recently, two storey extension costs used to be around £1,320 to £1,620/m² for a basic quality build, rising to from £1,860 and £2,100/m² for a very high quality finish. 

However, price increases in pretty much every area of the building industry of late have changed things somewhat.

“Over the last year we have seen typical two storey extension costs rise from £1,750/m2 to £2,000/m2 and well over, depending on design,” says Tim Phillips. “This has left some clients rethinking their projects with a 15% rise to soak-up

“People could consider project managing their extension themselves to find cost savings or even having a ‘shell and core’ build so they can complete items themselves if they have the necessary DIY skills or are happy to employ individual trades,” continues Tim. 

“Both procurement methods will certainly reduce the build cost and hopefully get their extension back on track.

You may be surprised to learn that double storey extensions actually don’t cost much more than single storey extensions per m2. 

The reason for this is that some of the most expensive elements of the build – the roof and the foundations – will still be required for both and will cost roughly the same regardless of whether you are building one or two storeys. 

“One of the major cost elements to consider in a single or two storey extension is the groundworks, however there is no real difference in structural design, so investigating any savings would reveal them to be extremely minimal,” explains Freelance Senior Quantity Surveyor Tim Phillips ([email protected]).

The only extra costs involved in building a two storey extension, as opposed to a single storey one, are the walls and new floor joists. 

For this reason, many people see two storey extensions as a more cost-effective way of adding extra space to their homes. 

This two storey extension to a Victorian terrace house in London, designed by Trevor Brown Architects, follows a staggered design that has maximised the overall floor space of the family home.   (Image credit: Darren Chung)

Are There Any Hidden Costs of Two Storey Extensions?

Before setting a final budget for your extension, be aware that there are some costs that are often missed off quotes or financial plans.

These include:

  • Design fees
  • Structural engineer’s fees
  • Surveys
  • Planning permission applications
  • Building Regulations applications
  • Party Wall Agreement, where required
  • A Lawful Development Certificate, if needed 
  • Fitting out — kitchens and bathrooms, for instance
  • Final decoration
  • Insurance

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Natasha is Homebuilding & Renovating’s Associate Editor and has been a member of the team for over two decades. An experienced journalist and renovation expert, she has written for a number of homes titles. She has renovated a terrace and is at the end of the DIY renovation and extension of her Edwardian cottage. She is now looking for her next project.

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Russia will propose to extend the regime of duty-free import of goods worth up to €1000

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Russia will propose to the EEC to extend the regime of duty-free import of goods worth up to €1,000 until July next year. Now the fee is levied at a rate of 15% of the amount exceeding the threshold of €1000. From January 2020 to April 2022, the duty-free limit was set at €200

Duty-free importation of goods worth up to €1,000 can be extended until July 2023. Russia’s representative at a meeting of the Council of the Eurasian Economic Commission (EEC), Deputy Prime Minister Alexei Overchuk, will come up with such an initiative. This is reported by “Vedomosti” with reference to the representative of the Deputy Prime Minister.

The issue of extending the duty-free import regime with a threshold of €1,000 has not yet been included in the agenda of the next meeting of the EEC Council on September 23, the protocol department of the commission reported. Overchuk will represent Russia at this meeting. The Ministry of Economic Development reported that they are working on an initiative to extend the duty-free threshold. If the topic of the duty-free import threshold at a meeting of the EEC Council is not raised by any member state of the commission, then this indicator will automatically return to the previous threshold of €200.

Related material

This threshold was valid until April 2022. The decision to increase the duty-free import limit from €200 to €1,000 was made at a meeting of the EEC Commission on March 17. The measure should allow Russians to make purchases in foreign online stores, the Ministry of Economic Development, the Ministry of Finance and the Federal Customs Service were appointed responsible for this. Until 2019, the duty-free threshold was €1,000, after which it was reduced to €500. The weight limit for the parcel was set at 31 kg.

If the value of the parcel exceeds the threshold amount or its weight is more than 31 kg, then a fee of 15% of the excess amount must be paid, but not less than €2 per 1 kg. The Ministry of Finance is most actively in favor of lowering the threshold, said a top manager of one of the largest Russian marketplaces. The interlocutor warned that the reduction would not increase the amount of taxes received from cross-border trade. “Once the threshold returns to the value of €200, this segment of the trade will simply go away,” he said.

Related material

Artem Sokolov, President of the Association of Online Commerce Companies (AKIT), noted that the current approach “creates an imbalance in electronic commerce and puts domestic players in unequal competitive conditions compared to online stores outside the EAEU.” According to Sokolov, foreign companies do not pay 20% VAT and import duties, which Russian companies must pay. The requirements of the Eurasian and Russian legislation in the field of technical regulation do not apply to foreign sites, the president of AKIT added.

Within the EAEU, explains Sokolov, a completely different principle of online commerce has been established: companies are subject to double taxation of VAT when selling goods through Russian Internet sites to individuals in the member states of the union. He clarified that the decision to raise the duty-free threshold to €1,000 was not discussed with Russian online retail players, but was dictated by the need to provide Russian consumers with access to goods amid the withdrawal of foreign brands. “Unlike parallel imports, which are now being mastered by more and more Russian companies, the measure adopted for specific tasks did not justify itself,” Sokolov summed up.

Related material

A spokesman for Ozon (also part of ACIT) said that with alternatives to the outdated range emerging and new supply chains being established, it makes sense to extend the €1,000 threshold. Alexander Ivanov, President of the National Distance Selling Association, noted that in 99% of cases, people buy through Internet sites what cannot be bought in Russia, because it is not produced here. Reducing the duty-free threshold will lead to infringement of consumer rights, the expert added.

Information from the Federal Customs Service of Russia dated 08.08.2022 “For the attention of citizens who are temporarily importing foreign vehicles for personal use.” Customs documents

Customs documents

online directory

On the extension of the temporary import of foreign vehicles for personal use

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Information of the Federal Customs Service of Russia dated August 8, 2022
“To the attention of citizens who are temporarily importing
foreign vehicles
for personal use”

has the right to extend the period of temporary import within the maximum period, which is 1 year. To do this, an individual must apply to the authorized customs authority before the expiration of the temporary importation period, submitting an application in any form and a passenger customs declaration issued when crossing the border.

In accordance with the law of the Eurasian Economic Union, temporary importation of foreign vehicles for personal use is processed by customs authorities located at checkpoints across the state border of the Russian Federation. However, operations for the extension of temporary admission may be carried out in customs authorities other than those located at the border, which have the appropriate competence. Their list was approved by the order of the Ministry of Finance of Russia dated January 14, 2020 N 4n “On the competence of customs authorities to perform certain customs operations in relation to goods.”

For example, individuals temporarily staying or permanently residing in Moscow and the Moscow Region can apply to the Exhibition customs post of the Central Postal Customs, Vashutinsky, Lytkarinsky and Lobnensky customs posts of the Moscow Regional Customs.