Floor Build-Up and Oversite Estimator
Estimate the hardcore, sand blinding, DPM, PIR insulation, and concrete you need for a ground-bearing extension floor, by floor area and layer depths, with an all-in cost.
Premium calculator — unlock with an Access Pass
This calculator is part of the Kitchen Extension Access Pass. Get full access to every calculator, guide, and tool — from planning through to completion.
Get Access PassOne-time payment. 24 months access.