How to estimate your build costs

Getting a firm grip on what goes into your project will help focus your design choices and ensure builder’s quotes are accurate; potentially saving you a small fortune, says Chris Bates

Build It’s virtual Benchmark House was recently costed using the Build It Estimating Service.

If you’re just starting out on a self build project, there’s probably one big question at the front of your mind: how much will it cost? After all, this is an opportunity to create a truly bespoke home and you’re understandably going to want to achieve the best design and build quality you can afford, without paying over the odds. The key to achieving this is to draw up an accurate budget and cost plan. Here’s how to get it right.

How can I establish a budget?

The first step to figuring out how much you have to spend is looking closely at your savings, any equity you have in existing property and investigating what kind of funds you could bring in via a self build mortgage.

The 155m2 scheme, which is intended to be of a good spec and finish, with manageable running costs, came in at a total budget of £261,738 (£1,688 per m2).

Armed with this information, you’ll have an idea of what you can afford in total for the plot and construction (including things like professional fees, services, a 10% contingency fund etc). If you already have a site in mind, you can then subtract the cost of the land (usually about 30%-40% of the overall spend) from your total sum to get an idea of what you’ve got left over for the work.