Grades and products for Leatherhead apartment floors
An anhydrite specification is written as a designation such as CA-C25-F5. CA means calcium sulphate. Read the number after C as compressive strength and the number after F as flexural strength; the unit is N/mm2. CA-C20-F4 is enough for a lightly used floor in a house. Flats, offices and the bulk of houses get CA-C25-F5. In a Leatherhead block, the communal corridors and entrance areas see heavier wear and may be specified as CA-C30-F6.
Alpha hemihydrate screeds are a further option outside this scale. They are chosen where a faster dry or a thinner section is needed, perhaps to fit a build-up under fixed door heights in an apartment, and each follows its own product data sheet for depth, drying and heating.
Low shrinkage is the reason calcium sulphate is popular in blocks. Big bays go in with hardly any joints, so a long open-plan flat floor stays in one piece. Where joints are needed, at doorways or changes of heating zone, the layout is planned before the pour and recorded so the flooring fitter can follow it.
The one thing it will not tolerate is persistent water. So in a walk-in shower room, a wet room or anywhere that could flood, the floor should be a flowing screed whose binder is cement, or traditional hand-tamped sand and cement. On a mixed specification we pour each material in its own area. Our anhydrite screed explained guide gives more background on the material.
From pour to flooring in a Leatherhead block
In the 2021 Census, 13% of Leatherhead homes dated from the years 2000 to 2014, and it is in flats and new build plots like those that calcium sulphate usually turns up on the drawings. Every calcium sulphate floor follows the same sequence once it has been poured.
As the floor dries, a weak skin called laitance builds up on top. Once the screed is dry enough, that layer is sanded off back to sound material and the dust removed. Skipping this step is one of the main reasons adhesives and levelling compounds fail on anhydrite. It is part of the floor preparation we carry out or advise on.
Then comes testing. Flooring suppliers tend to demand a drier reading from calcium sulphate than from cement, so a hygrometer, not the calendar, tells us when it is ready. If the flat has underfloor heating, running it gently from around day 7 can usually speed the drying, following a step-by-step programme.
Finally, the surface is primed with a product made for calcium sulphate, which stops a reaction with cement based tile adhesives. We leave you written advice on drying and on taking off the laitance. Close by, see anhydrite flow screed in Walton-on-Thames.
Anhydrite & Flow Screed prices in Leatherhead
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 Leatherhead
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 Leatherhead
Leatherhead is about 21.2 miles south-east of our Slough base as the crow flies, with postcodes including KT22 and KT21. The nearest towns to it are Epsom (3.8 miles), Dorking (4.4 miles), Ewell (5.1 miles) and Reigate (6.8 miles).
More on anhydrite screed, part of our screeding services.