CA grades for Westbury apartments and new plots
Calcium sulphate screed grades follow a simple code. The letters CA mean calcium sulphate, the figure after C gives compressive strength and the figure after F gives flexural strength, each measured in N/mm2.
Lightly used domestic floors take CA-C20-F4. Houses, apartments and offices generally take CA-C25-F5. Busier commercial areas and other heavier use call for CA-C30-F6. Choosing a higher grade than the floor needs adds cost without benefit, and choosing a lower one risks a surface that marks or cracks under load. If the site manager's drawing names a grade, that grade goes in, with bays and joints worked out well ahead of the pour. Calcium sulphate's low shrinkage means bays can be large, so long apartment corridors and open-plan ground floors need few joints.
Purpose-built flats make up 7% of Westbury's homes. Apartment floors often use this material, because it pumps easily up to each level and can be laid thin over acoustic or thermal insulation.
Products based on alpha hemihydrate are a different family again. They are chosen where faster drying or reduced depth matters, and their depth and drying follow the manufacturer's own product sheet.
We can also prepare the full build-up ourselves, from insulation to edge strip and membrane, so the floor is checked by the same team that pours it. Any gaps in the membrane or edge strip would let the screed leak or bridge, so those checks happen before the pump starts. For a plain comparison of anhydrite with traditional screed, read our anhydrite screed explained guide.
Sanding and testing anhydrite in Westbury before flooring
Three steps stand between a dry calcium sulphate screed and a finished floor.
First, the laitance. As the material sets, a soft, thin skin rises to the top. Once the floor is dry we sand it away; leave it, and adhesive or compound would be holding onto something weak that can let go later.
Second, the moisture test. Flooring makers often allow less moisture in a calcium sulphate base than in a cement one. We take a hygrometer reading to prove it suits the covering you have picked. With pipes in the floor, the heating can usually speed up the drying from about 7 days, cutting time off the programme.
Third, the primer. It must be a product compatible with calcium sulphate, applied once the laitance is off and the reading is right. Levelling over the top, where needed, follows the same rule; see levelling a Westbury floor.
Keep this material out of anywhere water may reach the floor. Food and dairy units, wash-down areas and wet rooms need a cement based flowing screed instead. For a specification in a neighbouring town, see anhydrite screed in Melksham.
Anhydrite & Flow Screed prices in Westbury
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 Westbury
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 Westbury
As the crow flies, our yard in Slough is about 69.1 miles from Westbury, which lies to the west-south-west. Postcodes here include BA13, and Warminster (3.9 miles), Trowbridge (4.2 miles), Frome (6.3 miles) and Melksham (8 miles) are close by.
More on anhydrite screed, part of our screeding services.
