Choosing a calcium sulphate grade in Daventry
Every calcium sulphate screed on a drawing should carry a grade. The letters CA identify the binder. After the C comes the crushing strength and after the F the bending strength, both in N/mm2. So a lightly used house floor might be CA-C20-F4, a typical home, flat or office CA-C25-F5, and a hard-working floor CA-C30-F6.
Now and then the drawing asks for alpha hemihydrate. A designer picks it when the programme is short or depth is tight, and that product's own data sheet then sets how thick we lay it and how long it dries.
Its real strength is how little it shrinks, so a flat's floor or an open new-build ground floor at Monksmoor Park can go down in wide bays with hardly a joint. Doorways and the line between two heating zones still get a joint, marked out on the plan ahead of pour day. It can go over insulation, underfloor heating or a concrete base, and our own team prepares that build-up.
Keep it out of rooms that may get wet. Any shower area, wet room or utility should have a flowing mix made with cement, or a hand-laid cement floor in Daventry. Anyone comparing products for a Daventry plot will find more in our anhydrite screed guide.
Laitance and drying on Daventry anhydrite floors
The last stage of a calcium sulphate floor happens weeks after the pour. While it dries, a soft, chalky skin called laitance rises to the top. Glue or compound fixed to that skin can let go, so when moisture allows we sand it away and seal the floor with a primer approved for calcium sulphate.
A hygrometer reading comes next. Flooring suppliers tend to set a tighter moisture limit for this material than for cement, and the floor must get under the limit your chosen supplier sets. With heating pipes inside, gentle heat from about 7 days onwards, brought up slowly, helps it dry.
What we did to dry and sand the floor is written down and left with you for the flooring fitter. On apartment projects, where flooring is often laid by a separate contractor, that note tells them what has been done and what to check. If a very smooth finish is needed for thin sheet flooring, a smoothing compound over the screed can follow once it is sanded and primed.
Anhydrite & Flow Screed prices in Daventry
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 Daventry
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 Daventry
As the crow flies, our yard in Slough is about 54.8 miles from Daventry, which lies to the north-north-west. Postcodes here include NN11, and Rugby (9 miles), Northampton (11.3 miles), Towcester (11.4 miles) and Lutterworth (13.7 miles) are close by.
More on anhydrite screed, part of our screeding services.