CA grades and specifications on Crowborough new builds
Anhydrite screed is labelled under the European screed standard with a code such as CA-C25-F5. CA stands for calcium sulphate. After C comes the compressive strength, after F the flexural strength, and both are given in N/mm2. Nearly every Crowborough job lands on one of three. A quiet domestic floor can be CA-C20-F4, a normal home, flat or office is usually CA-C25-F5, and CA-C30-F6 goes where the wear is heavier.
On Crowborough's newest plots, the developer's engineer picks the grade. We pour to that designation and do not substitute a different product. Now and then the drawings call for alpha hemihydrate instead, to dry sooner or sit thinner, and then the maker's own sheet governs depth and drying.
Apartment floors are the other place anhydrite fits. Purpose-built flats are 12% of Crowborough's homes, and a flat can often be poured in one continuous bay over its insulation and heating. The material hardly shrinks while it sets, which is why such big bays can go down with so few joints. Where the design calls for them, at doorways and the boundaries between heating zones, we still mark joints on plan before the pour.
To understand the material better, read our anhydrite screed explainer. If you simply want a pumped floor for an extension with no specification, start with liquid screed in Crowborough.
Before flooring: laitance and moisture in Crowborough
Anhydrite needs finishing work after it dries. The surface forms laitance, a thin, weak layer that adhesives cannot grip. Once the floor is dry enough, our crew sands that skin away, vacuums up and rolls on a calcium sulphate compatible primer. Laying tiles or LVT straight onto an unsanded surface is a common cause of flooring failure. On a new Crowborough plot, ask whether the laitance has been dealt with before your flooring fitter is booked, because the adhesive needs a sanded, primed surface to hold.
Moisture is checked next. Flooring manufacturers commonly want calcium sulphate drier than cement, so a hygrometer reading decides, not the calendar. Heated floors can normally be force dried from about 7 days, with the temperature brought up step by step rather than switched straight to full, so the floor dries evenly through its depth.
Water is where anhydrite stops. Put a cement based flowing screed, or sand and cement laid by hand for Crowborough wet rooms, in any shower room, wet room or leak-prone utility. For new plots in East Grinstead, see anhydrite screed in East Grinstead.
Anhydrite & Flow Screed prices in Crowborough
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 Crowborough
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 Crowborough
On the map, Crowborough sits south-east of Slough, about 47.8 miles from our base in a straight line (postcodes including TN6), next to Royal Tunbridge Wells (6.7 miles), Uckfield (6.9 miles), East Grinstead (8.6 miles) and Tonbridge (10.3 miles).
More on anhydrite screed, part of our screeding services.