Calcium sulphate grades on Earl Shilton new builds
Look at the floor notes on a new plot's drawings and the screed appears as a code. Taking CA-C25-F5, the CA is the binder, calcium sulphate, the C25 is how hard it is to crush and the F5 is how well it resists bending, both in N/mm2.
Three grades cover most work. The lightest, CA-C20-F4, is meant for house floors that see little traffic. CA-C25-F5 sits in the middle and covers the bulk of houses, flats and offices, and harder wear moves the choice up to CA-C30-F6. Where the specification names a grade we pump to it; where it does not, the use of each area decides.
Alpha hemihydrate screeds stand apart from that scale. A specifier chooses one when a plot must dry sooner or the floor has to be thinner, and each comes with a maker's sheet that sets its depth and drying, so the usual rules of thumb do not apply.
The main practical advantage of the material is its low shrinkage. It goes down in big bays with only a few joints compared with cement, handy on the open-plan ground floor of a new Earl Shilton house. Bays and joints are still marked out ahead of the pour, with doorways and awkward corners looked at most closely.
In Earl Shilton, 11% of homes are flats in purpose-built blocks. On apartment floors the material is valued for the same reasons: flat, low in joints and quick to force dry with the heating. The anhydrite screed guide explains the chemistry behind it in more detail.
Laitance and moisture checks for Earl Shilton floors
A dry calcium sulphate screed is not yet ready for flooring. Curing leaves a soft, thin crust on top, known as laitance, and it must be sanded away. Adhesive bonded to laitance fails with it.
Next comes the moisture test, which is stricter than for cement. Plenty of flooring makers allow less moisture in calcium sulphate than in cement, so a figure that would be fine on a traditional floor may be too wet on this one. Test with a hygrometer, not by touch or colour, because a pale surface can still hold water lower down. Where pipes are in the floor, running them from around day 7 usually speeds the drying along.
After that, the floor gets a primer made for calcium sulphate; one designed purely for cement bases is the wrong product. For thin sheet finishes, levelling compound over the primer can give an extra smooth base.
Keep it away from any floor that water might reach. A wet room, utility or garage in a new house is better off with a flowing screed bound with cement, or a traditional hand-laid screed.
Anhydrite & Flow Screed prices in Earl Shilton
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 Earl Shilton
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 Earl Shilton
As the crow flies, our yard in Slough is about 77.6 miles from Earl Shilton, which lies to the north-north-west. Postcodes here include LE9, and Hinckley (3.4 miles), Nuneaton (7.4 miles), Leicester (8.7 miles) and Bedworth (9.4 miles) are close by.
More on anhydrite screed, part of our screeding services.
