Reading an anhydrite specification for a Haywards Heath project
A specification for a block of flats or a new build plot in Haywards Heath will often give a screed designation such as CA-C25-F5. CA tells you it is calcium sulphate; the figure after C is compressive strength and the figure after F is flexural strength, both in N/mm2 as the European screed standard defines them.
On a Haywards Heath drawing, CA-C20-F4 would point to a lightly used domestic floor, houses, apartments and offices normally get CA-C25-F5, and CA-C30-F6 is kept for floors that take harder wear. We pour the grade written on the drawing, not a substitute.
Another route is an alpha hemihydrate product, picked when a floor must dry sooner or sit thinner, say in a tight build-up, with depth and drying set by its own product sheet.
Because the material barely shrinks while it cures, we can pour wide bays with hardly any joints, which works well in open-plan apartments. We plan the bay and joint layout before the pour, especially where floors meet at doorways or change heating zones.
Bolnore Village shows how much of the town is recent, with building there starting in 2002, and new build plots are where calcium sulphate is most often specified. In a flat in a converted building, a type that accounts for 4% of homes, the existing structure may change what is practical, so we check the build-up first. Our anhydrite screed guide goes further into what the material is.
Haywards Heath anhydrite floors: laitance, testing and wet areas
Calcium sulphate screed is not finished the moment it sets. As it dries, a weak, powdery surface layer called laitance forms on top. Once the floor has dried we sand that skin away; leave it, and any adhesive or levelling compound grips the laitance instead of sound screed. A primer made for calcium sulphate then goes on the sanded surface. Our floor preparation service covers the sanding and priming if you want it done separately.
Testing for moisture carries extra weight with anhydrite. Plenty of flooring makers allow less moisture in calcium sulphate than in cement screed, so a hygrometer figure that is fine on a sand and cement floor can be a fail on this one. Test before any finish goes down, and check the flooring manufacturer's own limit rather than assuming the figure used for cement screed. If pipes are in the floor, switching the heating on from roughly day 7 to force dry it shortens the wait.
Keep it out of rooms that could see water on the floor, wet rooms and some utility areas among them. For those spaces a flowing screed made with cement is pumped in the same way and finishes just as level. If you only need a fast, flat floor and no grade is specified, our general liquid screed page is the better starting point.
Anhydrite & Flow Screed prices in Haywards Heath
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 Haywards Heath
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 Haywards Heath
On the map, Haywards Heath sits south-east of Slough, about 43.9 miles from our base in a straight line (postcodes including RH16), next to Burgess Hill (3.1 miles), Uckfield (8.8 miles), Crawley (9 miles) and East Grinstead (9.7 miles).
More on anhydrite screed, part of our screeding services.
