There are two ways of approaching this. First, start with a new-build rate, say £900/m2, then deduct more or less 25 per cent for the items that don’t need upgrading, usually the external walls and the roof, giving a rate of £675/m2. You should then decide which other elements don’t need upgrading – such as electrics, or plasterwork – which may reduce the rate to £300m2. However, this approach should only be used to produce a rough figure to enable you to decide whether
to proceed or not. A safer way is to show the house to different tradesmen and obtain quotations from all of them to start your project with confidence. (For advice on finding, and assessing, a renovation project see our feature on page 148, Build It, January 2009.)