The real cost of building a house

Building a house is like any other big project. Not only is the cost of the house itself variable – dependent on the complexity of the building, the location and the materials as well as its size – there are a fair number of extra costs that you may not have initially thought of. That’s okay though – we’re here to tell you what some of those things are, so you can budget effectively from the start.


You will need to make sure the land is suitable to build on; this may involve a number of surveys by professionals, depending on what the plot is like. As well as a site survey by a surveyor – which maps the land and its natural and manmade features – you may need things like a soil survey to check for contamination and the risk of subsidence, a flood risk assessment and a tree survey.

If you’re renovating a dilapidated property, you’ll need a structural survey by a chartered surveyor to tell you about the condition of the building and reveal any potential problems with damp or subsidence.

Gas, water and electricity

If your site isn’t connected to the utilities, and presuming that you want it to be, the cost of this can vary widely and can run into hundreds or even thousands of pounds.


Even if you’re not a gardener, there will be work to do on the land around your home, which may include driveways, paths, patios, walls, lawns and planting.

Planning permission: The cost of a planning application is set by the government and is the same everywhere: £206 for an extension, and £462 for a new build, or for a conversion of another type of building into a home (assuming it requires planning permission, which nowadays not all conversions do).

Your district or borough council can also offer you advice on your application before you submit it, which is called pre-application advice. Councils are free to set their own charges for this, and they can come to hundreds of pounds.


A new home will need to be covered by both insurance during the construction process, and a self-build warranty, which protects you against major design and construction faults. What insurance you need will vary according to your situation, but you may need contractors’ all-risk insurance to protect you against things like fire and flooding; employers’ liability insurance in case anyone working on your site is injured; public liability insurance in case a member of the public is injured; and legal expenses cover if this isn’t included elsewhere in the policy.


You need to have a contingency budget of at least ten per cent of the cost of the project, and ideally between 15 and 20 per cent. Building a home almost always involves unexpected costs; be prepared for them. As architect Paul Testa put it in an interview with the House Planning Help website: “You’re always dealing with the ground. You’re dealing with weather. There are always going to be unknowns.”

South east London architects Bluelime Home Design has been designing custom-build and self-build homes across the area and beyond for 13 years – and now has offices in  DartfordBromleyErithBexley and Croydon. Call us on 01322 517632 to book a free architect consultation.

Share this post