Specifying anhydrite for Bishop's Stortford apartments
On a Bishop's Stortford drawing, calcium sulphate screed appears as a code along the lines of CA-C25-F5. The letters stand for the binder (CA, calcium sulphate), then strength in compression (C) and in bending (F), with the numbers in N/mm2.
Three grades turn up again and again: CA-C20-F4 where a home's floor sees light traffic, CA-C25-F5 for typical houses, apartments and offices, and CA-C30-F6 where use is heavier. Purpose-built flats are 17% of Bishop's Stortford's homes, and schemes such as the 149 apartments in Bellway's Goods Yard development off Station Road are the kind of building where the build-up is fixed in the specification and acoustic separation between floors matters.
New house plots are the other setting. Some 10% of Bishop's Stortford's housing dates from 2000 to 2014, and new plots have kept coming since at Stortford Fields and St Michael's Hurst. Where a plot's drawings name a CA grade, we supply that grade.
Shrinkage is minimal, which lets the screed go down in wide bays with very few joints. The layout of those bays, and especially the joints at thresholds and between heating zones, is set out before pour day.
Now and then an alpha hemihydrate product is named instead, for quicker drying or a slimmer floor, and its own product sheet then applies.
The general case for pumped screed is on our liquid screed page; this page stays with the material. For background, read anhydrite screed explained.
Sanding, testing and priming in Bishop's Stortford
As it sets, calcium sulphate grows a thin, weak top skin known as laitance, and that skin has to go. After drying, we sand it away and lift the dust, so the adhesive bonds to firm screed. If sanding is not already in the programme, our floor preparation service can carry it out.
Drying can be helped along. In a heated floor, the heating can usually begin drying the screed after about 7 days, turned up in gradual steps.
Next, a hygrometer goes on the floor. Because many flooring manufacturers set a stricter moisture limit for calcium sulphate than for cement, the test is the step that protects the floor covering. Record the result for the flooring contractor.
The last step is a coat of primer suited to calcium sulphate.
Where water may reach the floor, this material is the wrong choice, whatever its other strengths. Where a scheme includes shower areas or plant rooms, a cement based flowing screed is the alternative. For a scheme in Harlow, see anhydrite screed in Harlow.
Anhydrite & Flow Screed prices in Bishop's Stortford
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 Bishop's Stortford
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 Bishop's Stortford
On the map, Bishop's Stortford sits north-east of Slough, about 41.8 miles from our base in a straight line (postcodes including CM23), next to Sawbridgeworth (4.1 miles), Harlow (7.6 miles), Great Dunmow (8.7 miles) and Ware (9.2 miles).
More on anhydrite screed, part of our screeding services.
