Construction costs will, of course, be dependent on the quality of materials and workmanship you’re aiming for. But, as a basis for working out an initial budget, £1.5k per sqm is a reasonable estimate for your construction costs, to which you should add a contingency of 20% for unexpected remedial work.

So, were you planning to convert your existing kitchen of 20 sqm and add an extension of 15 sqm to give a combined area of 35 sqm, you might reasonably budget for construction costs of around £60k.

Based on construction costs of £60k, you might allow for the following fees: