Reading an anhydrite specification for a Tring plot
On a drawing or a specification sheet, calcium sulphate screed appears as a string such as CA-C25-F5. CA stands for calcium sulphate. Following that, C gives crushing (compressive) strength and F gives bending (flexural) strength, each in N/mm2, under the European standard for screed materials. A quiet domestic room can use CA-C20-F4; ordinary houses, flats and offices normally get CA-C25-F5; and CA-C30-F6 is the step up for harder wear.
A new plot in Tring will usually come with the grade already fixed by the engineer. We pour to it and do not swap products. Where the design calls for an alpha hemihydrate screed, chosen for faster drying or a thinner section, we follow that product's own data sheet.
Low shrinkage is why the material is specified. Big open ground floors and whole flats can go down in broad sweeps, barely interrupted by joints. Where joints are unavoidable, at doorways or between heating zones, they are drawn up and signed off ahead of pour day.
Purpose-built flats make up 11% of Tring's homes, and a flat being refurbished calls for the same grades and checks. For more on how it behaves, read anhydrite screed explained. If the base under a Tring floor needs shot blasting or preparation, that is done first.
Laitance, primers and moisture tests in Tring
Once the pour is done, the work turns to the surface. Drying anhydrite grows a flimsy top crust called laitance. Glue stuck to that crust can only hold as well as the crust does, so when the floor is dry we machine it off, hoover up and roll on a primer meant for calcium sulphate.
Moisture testing follows. Flooring brands frequently allow less moisture in anhydrite than in cement, so each reading is checked against the figure your chosen product gives. We use a hygrometer and record the reading, rather than judging the floor by its colour or the date of the pour. In a heated Tring house, the loops can normally start speeding the drying from around day 7.
Keep calcium sulphate out of places that may get wet. Where a washing machine could leak, or a shower or wet room will soak the floor, use a cement based flowing mix or a hand-tamped cement floor instead. For the heat-up side, see screed over underfloor heating in Tring.
Anhydrite & Flow Screed prices in Tring
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 Tring
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 Tring
Tring is about 18.1 miles north of our Slough base as the crow flies, with postcodes including HP23 and HP22. The nearest towns to it are Berkhamsted (4.3 miles), Chesham (6.5 miles), Aylesbury (6.6 miles) and Amersham (8.4 miles).
More on anhydrite screed, part of our screeding services.
