Anhydrite grades for Trowbridge flats and new plots
The European screed materials standard gives each calcium sulphate screed a coded designation. Take CA-C25-F5: CA stands for calcium sulphate, C25 for its compressive strength and F5 for its flexural strength, in N/mm2.
Three grades cover most work. Light domestic use calls for CA-C20-F4. Offices, apartments and the majority of houses take CA-C25-F5. CA-C30-F6 goes where wear is heavier. When an engineer's drawings fix the grade on a new plot, we pour that and nothing else. On a self-build or extension, we will recommend a grade based on how the rooms will be used.
Where a floor has to dry quicker or be laid thinner, the drawings may name an alpha hemihydrate product instead. Depth and drying times for those come from each product's own sheet.
In Trowbridge 12% of homes are purpose-built flats, and their floors are a good match for calcium sulphate. With so little shrinkage while it sets, an entire flat's floor can go down over insulation or heating as one big bay with hardly any joints. Any joints still required, perhaps at a doorway or a heating zone boundary, are mapped out first.
The material is not for wet areas. A bathroom with a level access shower, or a utility room where leaks are a risk, should get a cement based flowing screed. Our anhydrite screed guide explains the material more fully.
Preparing Trowbridge anhydrite floors for finishes
The job is not over once the pump has gone. Drying leaves a weak skin, known as laitance, across the top, and neither adhesive nor smoothing compound will hold to it. Once the screed has dried far enough, we sand that skin off and prime with a product that is compatible with calcium sulphate. A primer meant for cement may not hold on this material, and tiles or LVT laid over it can lift later.
Moisture is the other check. Lots of flooring makers accept less moisture in calcium sulphate than in cement screed, so a hygrometer test is needed, not a guess. With underfloor heating in place, the heating can normally force dry the screed from about 7 days and bring that date forward.
After the pour you receive our drying and laitance notes in writing, which tell your flooring contractor what has been done. If the final finish is LVT or vinyl, a thin smoothing coat over the sanded screed may follow. For the general case for pumped screed, see liquid screed in Trowbridge.
Anhydrite & Flow Screed prices in Trowbridge
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 Trowbridge
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 Trowbridge
On the map, Trowbridge sits west-south-west of Slough, about 69.1 miles from our base in a straight line (postcodes including BA14 and BA15), next to Westbury (4.2 miles), Melksham (4.7 miles), Bath (7.9 miles) and Frome (7.9 miles).
More on anhydrite screed, part of our screeding services.
