Work out a ballpark build cost for a single or double storey extension by multiplying your floor area by a rate per square metre. Every rate is editable, so you can match quotes you already have.
The calculator multiplies your floor area by the build rate, then adds professional fees and a contingency on top. For a double storey extension the footprint area is counted twice, once per floor, because you gain a room above without a second set of foundations.
Assumptions and limits. Figures are guide costs for a typical level site with normal access. They exclude VAT, kitchen or bathroom fit out beyond a basic allowance, knocking through into the existing house, and any structural work to what is already there. Ground conditions, planning conditions and where you are in Kent all move the number. Treat the result as a starting point for conversations, not a fixed quote.
For a firm price, send us your drawings or arrange a site visit.
