the build costs for house extensions explainedHow Much Does an Extension Cost?

There are lots of variables which will impact the price of your extension including soil type (which impacts the foundations); whether you’re constructing a single or two storey extension; what the extension will be employed for; and how much glazing you plan to designate.

Estimated Costs For Building an Extension in the UK

Depending what your location is in the UK, for a simple extension you’ll want to allow around £1,000-2,000/m². Keep in mind that the standard of specification you decide on will have a significant influence on the build cost. Experienced renovator Peter Nolan of Heath Hill Building and Roofing in Telford, states that a single storey extension will cost the pursuing per/m².

Basic quality £1,000 to £1,680
Good quality £1,680 to £1,920
Excellent quality £1,920 to £2,160

calculator costs2 Storey House Extension Costs

A two storey extension won’t cost a great deal more per square metre according to Martin King, director at M A King Home Improvements Rayleigh because, besides the additional internal fixtures and finishes, you are only adding walls and floor joists – a roof and foundations are needed whether your extension is single or two storey.

Remember: Balance the total amount you are able to spend on your extension with the projected value it’ll add to your home.

Ways to Finance Your Extension

There are numerous options when it comes to borrowing money to finance your extension. Nonetheless prudence is the watchword – if you access more than you require you might do unnecessary things in the course of the job and have problems paying it all back. So remain conservative.

In an ideal world, we would all finance our projects using our savings, but with recent years having offered poor interest rates, the financial scenery has been one which favours credit seekers over savers. If you need to borrow the money, your easiest solutions are:

Credit card: If you wish to lend thousands rather than tens of thousands for your work, an interest-free credit card is a good choice. Look around – the best deals supply up to 27 months of zero-rated spending.

Loan: Unsecured loans of up to around £25,000 are best for smaller jobs. The loan might be enough to cover the building work and if you are fitting kitchens or bathrooms in your extension you can often purchase these on finance from bigger shops. Just keep track of repayments as they can rapidly add up when you borrow from several sources.

Remortgage or secured loan: If you are borrowing more than £25,000 you may want to remortgage your home or take out a secured loan against your home. Several building societies offer what is referred to as a Home Improvement Loan up to £200,000.


Your builder will generally stage payments for each phase of the project. Try not to make any installments in advance. If it is required to purchase a high priced item perhaps a bathroom suite or kitchen some months prior to its installation, you should make sure it’s in your name and not that of the building contractor, just in case they should go out of business. When necessary you should go to the place where it is stored and make sure the ownership is transferred to yourself.

Your designer will impose fees based on the work involved, so an exact quotation of the fee would be a very helpful thing to have prior to deciding to give the go-ahead for plans to be prepared.

It is wise to check what any quotation includes and who is financially responsible any local authority application fees. Also, ask if any provision has been made should structural calculations be necessary.