Calcium sulphate grades for Coventry flats and housing sites
Grades for calcium sulphate come from the European screed materials standard. In a designation like CA-C25-F5, CA is the binder, C25 is the compressive strength and F5 the flexural strength, both in N/mm2.
CA-C20-F4 is the lightest of the three, meant for domestic rooms that see little traffic. Apartments, offices and homes in general take CA-C25-F5. The tougher CA-C30-F6 is for floors expected to work harder.
A new housing or apartment scheme comes with an engineer's specification, and we pour the grade written there, without swapping in a different product. An alpha hemihydrate product in the specification signals that the designer wants quicker drying or a slimmer floor. Its own data sheet then fixes depth and drying, and that is what the crew follows.
The material's low shrinkage is why it suits apartment floors. A Coventry flat can go down as broad bays with hardly any joints, and the few it needs are set out ahead of pumping. Beneath the screed, our crew puts in the insulation, membrane, edge strip and, in a block, any acoustic layer.
Refurbishment is the other route in. Post-war blocks such as those at Tile Hill have acoustic screeds as part of any refurbishment, and a calcium sulphate floating floor over acoustic insulation is one way to rebuild them. Our anhydrite screed explainer explains the material at more length.
Laitance and moisture checks on Coventry floors
A calcium sulphate floor is not ready for tiles or LVT the moment it hardens. As it dries, laitance, a weak surface layer, forms on top. Adhesive laid on laitance bonds to the skin rather than the screed and can pull away later. That is why, when a Coventry flat floor has dried, the laitance is sanded off before a calcium sulphate compatible primer goes down.
The moisture test follows, and it is the step that decides when the flooring contractor can start. Flooring firms often set calcium sulphate a tighter moisture limit than cement, so the readiness call comes from a hygrometer, never a calendar date. If heating pipes run beneath, force drying can normally start around day 7, as covered under heated screed in Coventry.
Do not use calcium sulphate where a floor may get wet. Bathrooms with a shower, wet rooms and utilities should go on cement instead, either as a flowing mix or as hand-laid sand and cement in Coventry. For a straightforward pumped extension floor without a specification, our liquid screed in Coventry page is the better starting point, as it deals with the pour and access rather than the specification.
Anhydrite & Flow Screed prices in Coventry
Liquid flowing screed (which includes anhydrite): £24 to £31 per m² supplied and laid (MyJobQuote, August 2026), so £960 to £1,240 for 40 m². MyJobQuote does not say whether these figures include VAT. See our floor screeding cost guide or screed calculator.
Who lays your anhydrite and flow screed in Coventry
K & B Screeding’s own team, led by director Donatas Bardisevicius. Founded 2019, company 12298780.
See what customers say in our Google reviews and on our testimonials page.
Anhydrite & Flow Screed from Slough to Coventry
On the map, Coventry sits north-north-west of Slough, about 70.8 miles from our base in a straight line (postcodes including CV1, CV2, CV5 and CV3), next to Bedworth (5.1 miles), Kenilworth (5.4 miles), Nuneaton (8.1 miles) and Royal Leamington Spa (8.1 miles).
More on anhydrite screed, part of our screeding services.