What is a Fair Price to Pay For a House Extension?

Are you thinking about building an extension to your property? As we are sure you are aware; an extension can considerably increase the value of any house, but how much are builders charging? What is a fair price to pay for both a single and a two storey extension? We asked seven builders to quote us and below you can find an average of those prices, use this as a guide for reference.

The team here at Quotation Check has plenty of experience when it comes to researching cost and price guides for home improvement projects; it’s what we do best.

To date, we have investigated over 100 prices charged by builders, roofers and other tradespeople.

This page is all about extensions, and we last updated it on the .

How We Got Our Prices

As frequent visitors to our site will know, we usually gather quotes and estimates from tradespeople around the country and then publish an “average” figure for those regions.

This process involves asking friends and family members who live in different parts of the country to do some of the work for us.

Because house extensions are so complicated and involve a lot of communication between the homeowner, architect, the builder and other tradespeople; we only gathered one set of quotes – for our property in the south of the United Kingdom.

Don’t let this put you off, our price guide can still be very valuable to those looking for a cost guide.

Our Project – Key Points

The property we refer to below is a typical 30-year-old, 2-bed house but with enough space for a rear extension to allow for the following:

  • Extra double bedroom upstairs
  • Remodelling of existing space upstairs
  • Extend and remodel the kitchen
  • Extend the front room to allow for extra dining space

What’s Included in our Figures Below?

Below you will find a guide for the extension and it includes the following:

  • Architects fees
  • Planning permission (required for our property)
  • Skip hire
  • All labour costs including:
  • Labour for the kitchen which is to be supplied by the customer
  • Labour for wooden flooring downstairs and carpet upstairs which is to be provided by the customer
  • All other materials to be supplied by the building company and costs included in the quote
  • All materials are “standard” quality; upgrades will involve additional materials cost
  • VAT at 20%

In essence, our price below includes the cost of everything involved with a two storey extension, except for the kitchen and flooring materials which are to be supplied by the customer at additional cost.

We have created separate cost guides for a kitchen here and wooden flooring here.

Quote Breakdown

Below is a chart showing the approximate allocation of funds, this varied from company to company but we feel this is a good guide:

See All The Quotes We Received

The chart below shows all the quotes we received, we have rounded the prices to the nearest £500:

Average House Extension Cost

Below is our price guide for a two storey house extension, we have based it on an average of the quotes and estimates we received from builders in January 2017:

LocationSmall BusinessLarge Business (5+ employees)
Need a Custom Price? >Compare Up To 3 Personlised Quotes Here
London AreaN/AN/A
South, SW and MidlandsN/A£47000
Outer Region and NorthN/AN/A



Get a Personalised Price

Because the specifications of our house may be different to yours, we suggest you arrange for your own customised quote:

  • Submit specifics of your house extension
  • Explore the ratings and reviews of the builders
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What About a Single Storey Project?

When we approached our chosen building companies for a two-storey extension price, we also enquired about the approximate cost for a single storey.

The average price for a 4m x 5m single storey extension was £33000; again this figure includes everything except the supply of the kitchen and the flooring throughout.

That figure is to extend the kitchen and front room, with a tiled roof but excludes the cost of the kitchen itself (just the labour).

What About “Per Metre” Pricing?

We asked our chosen builders how they calculate their figures and whether they use a “per square metre” calculation. Most told us they didn’t use a per metre system and preferred to fully customise each quote as “every house is different”.

A few of the builders suggested a starting price of £1500 per square metre for a single storey and between 40% and 60% extra for a double storey.

Again, these figures include everything except for the flooring and kitchen itself.

A budget kitchen can cost £5000 if you are thrifty, but our research suggests a figure of £8000 is more common. A top-of-the-range one can cost tens of thousands, even for a 3-bedroom house.

Extras You’ll Want to Consider

Our prices are for a typical house extension; you may end up paying more if:

  • You want a higher quality of finish on fittings
  • Large bi-folding doors or lead windows
  • Woodgrain effect Upvc windows and doors are more expensive than white framed products
  • You need an existing structure removed, perhaps a conservatory
  • The ground is not ideal and needs excavation to additional depth for structural support
  • Access is always important, and issues could delay the completion adding extra cost
  • Steelwork is expensive and the amount needed is different for every house

How Location Affects the Price

While we only gathered quotes and estimates for our property in the south of the UK, we do have experience in the building industry and have plenty of friends with knowledge too.

Our research suggests that while a price per metre of around £1500 for a ground level extension is typical for the South of the UK, the further away from London you live, the cheaper the cost.

You can expect London prices to be higher than the figures we have shown here.

How Long Will The Work Take?

The tradespeople we contacted for a quote also gave us a completion timescale.

While there were differences, the average time given to us was 13 weeks.

You should also note, our experience in gathering quotes has taught us that tradespeople are often optimistic when it comes to timescales.

How many tradespeople are working on the project also affects the time to completion, the project will be completed sooner if the company puts more workers on the extension.

Compare Extension Quotes With Rated People

We recommend Rated People as they are a great place to read reviews and source extension quotes.

Rated People Have Appeared in:

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  • Only Genuine Customers Can Leave Reviews (unlike other sites)
  • They are a National Company and Cover Most of the UK
  • Helps You Avoid Cowboys
  • Tens of Thousands of Tradespeople Are Listed
Click Here to Get Your Free Roofing Quote

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