Screeding Materials

Screed is the layer almost nobody sees but everything above it depends on. It encapsulates the underfloor heating pipes, gives the tiler or flooring installer a flat surface, and sets the programme because it has to dry to a measured moisture level before any floor finish can go down.

Two products dominate UK domestic pours: traditional sand-and-cement, mixed on site and laid by hand, and liquid anhydrite, pumped from a truck and self-levelling. They dry at different rates, need different preparation before tiling, and behave very differently over UFH. Picking the wrong one, pouring it at the wrong depth, or laying a floor before it has dried is one of the most common and expensive defects in an extension.

Where to start

If you have underfloor heating, read liquid anhydrite screed first. It flows around the pipes without voids, but it needs its surface laitance sanded off and must reach the right moisture reading before tiles or flooring go on. If your builder has quoted a traditional floor, read sand-and-cement screed to check the mix, the minimum depth, and the difference between curing and drying that catches flooring programmes out.

The guides

Pumped. Liquid anhydrite screed, covering depths, laitance removal, the UFH commissioning sequence and moisture testing.

Hand-laid. Sand-and-cement screed, covering mix ratios, depths, surface regularity classes, and when it is still a sensible choice over UFH.

Where these fit in the build

The pipes go down at underfloor heating, the pour happens at screeding, and the moisture test and surface preparation come before flooring and tiling. Use the screed drying time calculator to see how long your floor will hold up the programme, and the UFH and screed cost estimator to sense-check the quote.