Calcium sulphate grades for New Milton apartment floors
Anhydrite is ordered by its designation. Its first letters, CA, mark the calcium sulphate binder; the numbers after C and F are its squashing and bending strengths in N/mm2, as the European screed materials standard lays down. For New Milton houses and flats, it nearly always comes down to three:
CA-C20-F4, where a domestic floor sees little traffic.
CA-C25-F5, standard in most homes, apartment blocks and offices.
CA-C30-F6, for floors due to see heavier use.
Where an engineer has drawn up the job, for apartments or a fresh plot, their grade is the one we deliver. Just 13% of New Milton's homes have been built since 2000, so calcium sulphate is as likely to end up in an extension or refurbishment as in a new block. Without a formal specification, we propose a grade based on the rooms and finishes.
Alpha hemihydrate products are a parallel option, used where quicker drying or a slimmer section is wanted, each following its own product sheet for depth and drying.
Because calcium sulphate shrinks so little, big bays can be poured with few joints, letting an open-plan flat living area run as one floor. We still mark joints across doorways and along the edges of each heating zone, all agreed before the pour. For the material's background read our anhydrite screed guide, and for pump access see pumped liquid screed in New Milton.
Laitance and moisture checks before New Milton floors are finished
As it dries, calcium sulphate screed develops a thin, weak top layer, the laitance. Leave it and adhesives and compounds cannot bond to the screed underneath. So once the moisture has dropped, that skin is machine-sanded away and a primer made for gypsum-based screed goes on.
Moisture is the next test to pass. Flooring makers often give calcium sulphate a lower limit than cement screed, so a hygrometer reading decides when the covering can go down. If pipes run through the floor, switching them on gently from around day 7 normally speeds things up.
Water and anhydrite should never meet. For a shower room, a wet room or a utility where the washing machine might leak, choose a pumped cement screed or a hand-laid cement one. In a flat or house with anhydrite elsewhere, those rooms are poured separately with a planned joint.
In existing buildings where the base under a new calcium sulphate floor needs attention first, our floor preparation work gets it ready before the pour. That can mean scraping off old adhesive, cutting out a hollow screed or making sure insulation boards lie flat and fully supported.
Anhydrite & Flow Screed prices in New Milton
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 New Milton
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 New Milton
On the map, New Milton sits south-west of Slough, about 69.5 miles from our base in a straight line (postcodes including BH25), next to Lymington (5 miles), Christchurch (5.6 miles), Ringwood (8.8 miles) and Bournemouth (10 miles).
More on anhydrite screed, part of our screeding services.
