What the CA grades mean for Kidlington floors
Calcium sulphate screeds are classified with two numbers under the British and European screed standard. Spot the C on a Kidlington drawing and you are reading compressive strength; the F gives flexural strength, and both come in N/mm2. A house with only light foot traffic can manage on CA-C20-F4. Homes, flats and offices are normally drawn up at CA-C25-F5. Busier communal areas in a block may move up to CA-C30-F6 for heavier use.
Next to the CA grades you may see alpha hemihydrate named. They are selected where faster drying or a thinner section matters, and each is laid and dried to its own product sheet rather than to a general rule.
The reason calcium sulphate suits apartments and new plots is its low shrinkage. Bays can therefore be large, and an entire apartment or ground floor often goes down with none of the closely spaced joints cement screed would need. Even so, we set out bays and joints in advance, especially through doorways and where the structure beneath changes.
Its weakness is water. Wet rooms, or a utility with a floor gully, go better in cement based flowing screed, and we pour that as well. How a flowing screed is pumped and placed is covered on our page about liquid screed in Kidlington, and the guide to anhydrite screed explains the material further.
Preparing Kidlington anhydrite floors for tiles and LVT
A Kidlington anhydrite floor grows a soft skin, laitance, on top while it settles. It has to be removed by sanding once the floor is dry, before any primer, adhesive or compound touches it. A covering bonded to laitance can fail even when the screed underneath is sound.
Moisture is the other trap. Flooring brands usually want calcium sulphate drier than cement screed, so any reading on a Kidlington floor has to be judged against the figure for the right material. That number comes off a hygrometer placed on the Kidlington floor. Where the flat or new plot has heating loops in the floor, switching them on from roughly day 7 usually speeds the drying, and on a new build that can bring the flooring date forward by a useful margin.
Primer has to be a type made to work on calcium sulphate. Check this twice where cement based tile adhesives and levelling compounds will go on top, which is one reason our handover advice goes to the flooring fitter in writing.
On a Kidlington new build, these steps often fall between trades. Agreeing who sands, tests and primes before the pour avoids a floor that is ready on paper but not in practice. If a smoothing coat is needed for sheet vinyl or LVT afterwards, see floor levelling in Kidlington, and for dry times in general, our drying time guide.
Anhydrite & Flow Screed prices in Kidlington
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 Kidlington
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 Kidlington
Kidlington is about 34.1 miles north-west of our Slough base as the crow flies, with postcodes including OX5. The nearest towns to it are Oxford (5 miles), Bicester (7.8 miles), Witney (8.8 miles) and Abingdon-on-Thames (10.5 miles).
More on anhydrite screed, part of our screeding services.
