It’s the number one nightmare for self-builders and renovators: a project spiraling wildly out of control, with the budget blown and financial disaster ahead. The good news is that, despite what you might think after watching an episode of Grand Designs, this situation is easily avoidable.
Everyone starts out on a new build or renovation project with a set figure in their head of what they would like to spend. There’s probably also a figure in the back of their mind that is the absolute limit they can go up to. These figures – the budget – are critical to the success of the project regardless of its scale or ambition.
The trouble is that for most people new to the process, getting a realistic idea of what these costs might be is very difficult — for various reasons. Most commonly, when a new self-builder asks what it might cost to build their own home, the answer is simply impossible to give, because there are so many unknowns.
If getting an accurate idea of what your project will cost – and, just as importantly, ensuring that it stays within your budget expectations during construction – is important to you, then you’ll need to do some in-depth DIY estimating, or get some professional help.
First things first, in order to estimate your build costs accurately, you will need a correct (and final) set of building drawings. It’s impossible to be specific about expected costs if you don’t yet have access to the full detail of materials required (from type of joists and bricks through to finishes). If you are still keen to come up with an estimate of your expected costs for a self-build project, then use the build cost information on this very site (Build Cost Calculator). It gives, based on a series of questions regarding expected quality of finish and personal involvement, an estimated cost/m². Based on figures published by the Build Cost Information Service – part of the Royal Institute of Chartered Surveyors (RICS — the body that regulates chartered surveyors) – it offers about as accurate a ‘guesstimate’ as you can hope for.
Extensions and renovations are much harder to give estimates for as the limited floor areas/individual nature of projects renders cost/m² figures meaningless.
Builders’ merchants will, on the whole, be happy to offer a free ‘take-off’ service from your plans (quantities and costs for materials but not labour), however this is only the case if they can be assured of getting some level of work out of the deal.
Secrets of Budget Control
• Get the design settled and in line with your budget. Employ a designer who understands your budget and has proven examples of finished projects brought in on similar costs.
• Don’t go out to tender with builders until you have nailed your specification. Send out copies of full building drawings and detailed specs of material requirements.
• Don’t change your mind along the way, and if you do, ensure you have a process in place for agreeing the extra costs incurred.
• Employ a quantity surveyor on larger projects to give you an expert assessment of the cost of building to your plans; and retain their services during the project to ensure costs remain under control.