Horsham apartment floors and the CA grades
When a drawing for a Horsham apartment block or new build plot names the screed, it usually reads something like CA-C25-F5. CA means calcium sulphate. After C comes the compressive strength and after F the flexural strength, each in N/mm2 under the European screed standard.
Three grades cover most work. Lightly used domestic floors get CA-C20-F4, the middle grade CA-C25-F5 covers most houses, apartments and offices, and floors facing heavier wear take CA-C30-F6. Next to those sit alpha hemihydrate products, which a designer picks to dry sooner or build thinner, and every one comes with its own product sheet to follow.
Since this material hardly moves while curing, a large area can go down as one bay with very few joints. Apartment floors with open living areas benefit from that. We mark out bays and joints ahead of the pour, putting a joint across a doorway or between heating zones if one is needed.
New building has been a modest part of Horsham recently, with 8% of homes built between 2000 and 2014. The former Novartis plant, a major employer until 2015, is closed and scheduled for redevelopment. Any scheme that replaces it will come with its own specification, and where that names a CA grade we work to it rather than a substitute.
For the material in more depth, see anhydrite screed explained.
Finishing anhydrite floors in Horsham before flooring
Dry does not yet mean ready on an anhydrite floor. Curing leaves a soft top film, laitance, which has to be sanded away. If adhesive or levelling compound goes straight onto laitance, the bond fails at that weak layer. Then a primer designed for calcium sulphate seals the sanded surface.
Moisture is the other check. Flooring makers often set a tighter moisture figure for calcium sulphate than for a cement floor. So a reading that sand and cement would pass can still fail on anhydrite; a hygrometer test, checked against the maker's own limit, settles it. Where the floor is heated, switching the system on from about 7 days onwards to force dry it saves time.
Anywhere water could reach the floor, anhydrite should not be used. In wet rooms and similar areas, a cement based flowing screed gives a similar pumped finish without the risk. If you need sanding, priming or other groundwork done, see floor preparation. Crawley is about seven miles away, and our Crawley anhydrite page covers the material there.
Anhydrite & Flow Screed prices in Horsham
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 Horsham
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 Horsham
On the map, Horsham sits south-south-east of Slough, about 35.3 miles from our base in a straight line (postcodes including RH12 and RH13), next to Crawley (7.1 miles), Horley (10.4 miles), Haywards Heath (10.9 miles) and Burgess Hill (11.2 miles).
More on anhydrite screed, part of our screeding services.