Grades and products for Calne plots and flats
On a drawing, anhydrite screed shows up as a short code. Take CA-C25-F5. The letters CA give away the calcium sulphate binder; 25 is its compressive strength and 5 its flexural strength, measured in N/mm2 to the European screed standard.
Three grades cover most specifications. Domestic rooms with little foot traffic get by on CA-C20-F4. Most Calne houses, flats and offices sit happily on CA-C25-F5. Busier, harder working floors move up to CA-C30-F6. Purpose-built flats make up 10% of Calne's homes, and CA-C25-F5 is the grade that covers apartments.
Alpha hemihydrate products are the other option a specification may name. Designers pick them to dry sooner or to go down slimmer, and every one carries a product sheet setting its depth, drying and heating. On those jobs the product sheet, not the rule of thumb, is what we work to.
With so little shrinkage, big bays go down with only a few joints. That is planned before the pour: bay sizes, joint positions over any thresholds, and how the floor meets the walls. Our anhydrite screed explained guide goes into how the material behaves while it cures.
One rule sets its limits. Water that keeps reaching anhydrite softens it, so it is kept away from any floor likely to get wet. In a wet room, utility with a drain or level access shower, a cement based flowing screed or a sand and cement screed laid to falls goes in instead.
Laitance and moisture before flooring in Calne
Curing anhydrite leaves a soft, weak crust on top, and that crust is the laitance. It has to come off. With the screed dry, a sander takes it down to hard material, the dust is hoovered off and a primer designed for calcium sulphate goes on. Tile adhesive or LVT laid over laitance can debond. Sanding and priming of this kind fall under our floor preparation work.
Moisture is the second check. Lots of flooring brands allow less moisture in anhydrite than in a cement base, so a reading that clears one product can still rule out the next. A hygrometer test confirms where it stands. From about day 7 the underfloor heating can usually be used to force dry it, which keeps the build programme moving.
Where a 2000s ground floor is being retiled, the same points apply if it turns out to be calcium sulphate. The original build records, or a check on site, should establish which type of screed is down before any primer is chosen. We also pour calcium sulphate in nearby towns, including anhydrite screed in Royal Wootton Bassett.
Anhydrite & Flow Screed prices in Calne
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 Calne
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 Calne
On the map, Calne sits west of Slough, about 59 miles from our base in a straight line (postcodes including SN11), next to Chippenham (4.9 miles), Devizes (6 miles), Melksham (7.3 miles) and Corsham (7.8 miles).
More on anhydrite screed, part of our screeding services.
