UFH and Screed Cost Estimator

Floor screed for a UK extension typically costs £11 – £18 per m² for traditional sand-and-cement, or £18 – £34 per m² for liquid screed that pumps in and self-levels. Those rates cover supply and laying of the levelling layer that sits on top of your insulation and slab, ready for tiles or vinyl. They do not cover the floor finish itself, or the heated pipes if you are running underfloor heating.

This estimator turns those rates into a realistic ballpark for your own floor. Enter the area, choose liquid or traditional screed, set the depth, and tick the box if you want an underfloor heating system costed alongside. The result gives you a volume, a cost range, and a drying estimate, so you can check a builder's quote instead of guessing at one lump figure.

What drives the cost

The single biggest lever is screed type. Liquid screed carries a clear premium over hand-laid traditional screed, and the gap is real money across a whole floor. The trade-off is performance: liquid screed encases heated pipes completely, conducts heat better, and reaches the flat finish that large-format tiles need under BS 8204. If you have heated pipes in the floor, that premium usually earns its keep. If you do not, a groundworker or plasterer laying sand-and-cement is the economical call.

Depth matters too, because you pay by the cubic metre of material. A thicker floor uses more screed and dries more slowly. Two costs that the per-m² rate hides are worth pricing separately: laitance removal on an anhydrite floor, which is the mechanical sanding of the weak surface layer a few days after the pour, and the calibrated moisture test before tiling. Ring at least two screed companies directly for a quote. A screed specialist price often comes in well below a builder's supplier markup.

A worked example

Take a 30m² rear extension floor with wet underfloor heating. At the liquid screed rate of £18 – £34 per m², the supply-and-lay figure lands in the region the calculator shows above, before the heating system. Add the wet system itself, meaning the manifold, pipe loops, and commissioning, at £1,500 – £3,500, and you have the floor build cost in full. Scale up to a 50m² floor and the screed alone sits around £2,000 – £3,000 once truck and pump mobilisation is counted.

Then plan the wait. A 50mm liquid floor over heated pipes dries over weeks, and the calculator estimates the days for your depth. Before any tiles go down, fill and pressure-test the pipes ahead of the pour, then confirm the floor is dry with a sealed hygrometer test rather than a date in the diary. Getting that sequence right is the difference between a floor that lasts and one that lifts.