Reading anhydrite grades for Stanton Cross and Glenvale Park
On a site drawing, an anhydrite screed shows up as a short code. Read CA-C25-F5 from left to right: the letters CA mean calcium sulphate, C25 is 25 N/mm2 in compression and F5 is 5 N/mm2 in bending, with both tested to the European screed standard. The three common grades each have a typical use. For lightly used domestic floors, CA-C20-F4 does the job. CA-C25-F5 goes into the majority of houses, flats and offices, while CA-C30-F6 is saved for harder wear.
On a mixed development, different buildings can call for different grades, so we pour to the grade on each drawing and nothing else.
Alpha hemihydrate screeds sit apart from these grades. Specifiers pick them when quicker drying or a thinner layer is needed, and the depth and drying for each come from that product's own data sheet.
The material's low shrinkage is why calcium sulphate suits big, open ground floors. Bays can be large and joints few, and we mark out where both go before pouring, taking extra care where one heating zone meets the next. As a floating floor on insulation in a house, its minimum is about 35mm, and with heating pipes it needs 25mm or more above them. Most new houses on these plots have heating pipes under the screed, so read our page on heated screed build-ups alongside this one. For more on how the material behaves from pour to handover, see anhydrite screed explained.
Laitance and moisture on Wellingborough apartment floors
With 15% of Wellingborough's homes being flats, apartment floors are an obvious place for calcium sulphate, and it often goes over acoustic layers between storeys. Wherever it goes, the handover follows the same steps.
First, the laitance. As it cures, calcium sulphate leaves a thin, weak skin on top. When the screed has dried out we sand that skin away; leave it and adhesives or compounds grip the skin instead of the screed, and they can let go.
Second, moisture. Plenty of flooring makers are stricter about moisture in calcium sulphate than in a cement screed, so a reading that would be fine on a cement floor can fail here. A hygrometer test tells you where the floor stands. From around day 7 the heating can normally be run to speed the drying, which is useful when the programme is short.
Third, primer. After sanding and drying, we prime it with a product that suits calcium sulphate before any cement based adhesive or compound goes near it. We hand this drying and laitance advice over in writing.
One limit applies. Keep calcium sulphate out of a wet room, a plant room or anywhere else water may sit, and for those rooms our quote would suggest a flowing screed with a cement binder. If your own trades are not sanding the floor, our floor preparation team can.
Anhydrite & Flow Screed prices in Wellingborough
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 Wellingborough
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 Wellingborough
As the crow flies, our yard in Slough is about 53.3 miles from Wellingborough, which lies to the north. Postcodes here include NN8, and Rushden (4.1 miles), Burton Latimer (4.2 miles), Kettering (6.9 miles) and Raunds (7.3 miles) are close by.
More on anhydrite screed, part of our screeding services.
