Anhydrite grades and bays for Marlow projects
Anhydrite is just another name for calcium sulphate screed. Its designation sets the strength, with the C figure for compressive and the F figure for flexural, each in N/mm2. CA-C20-F4 covers floors that only take light domestic traffic. Step up to CA-C25-F5 for the bulk of houses, flats and offices, and to CA-C30-F6 where wear is heavier. When the drawings state a grade, that is the one we supply; when they do not, we will suggest one for the use, the floor finish and any heating underneath.
Alpha hemihydrate products form their own family, picked when the screed has to dry faster or be laid thinner. The maker's data sheet for each one sets its depth and drying time, and they can suit a Marlow refurbishment where the floor height is already fixed.
Because shrinkage is so low, big areas can go down as large bays with few joints, although we still plan the bays and joints round doorways and changes in floor shape before pouring.
New plots barely feature in Marlow, where only 4% of homes date from 2015 or later, so extensions, conversions and flats matter here as much as new build. Laid over heating pipes, it can take its first warmth from around 7 days. To read more about the material, try anhydrite screed explained; for heated floors, see the underfloor heating screed page.
Before flooring goes on a Marlow anhydrite floor
Flooring cannot go straight onto calcium sulphate screed; three jobs come first.
Laitance has to be removed. Fine material rises as the screed settles and forms a weak skin on top, which is sanded off once the floor is dry so the primer and adhesive grip sound screed.
Moisture has to be tested. Compare a hygrometer reading with the limit printed on the flooring or adhesive data sheet. Lots of manufacturers set calcium sulphate a lower limit than cement, so never assume a figure. Heating pipes in the floor, if there are any, can usually be run from about 7 days to force the drying along.
The surface has to be primed, with a product that suits both calcium sulphate and the adhesive going on it.
Anhydrite is a poor choice wherever water may reach the floor. Any bathroom or utility room in the same Marlow property needs a cement screed instead, laid by hand as traditional sand and cement or poured as a flowing cement based mix. If the sanded floor still falls short of SR1 for thin sheet flooring, see our floor levelling page for Marlow.
Anhydrite & Flow Screed prices in Marlow
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 Marlow
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 Marlow
On the map, Marlow sits west-north-west of Slough, about 6.3 miles from our base in a straight line (postcodes including SL7 and SL6), next to High Wycombe (4.1 miles), Maidenhead (4.2 miles), Henley-on-Thames (6 miles) and Beaconsfield (6.3 miles).
More on anhydrite screed, part of our screeding services.
