The Anhydrite Liquid screed we install is made from Calcium Sulphate and is design to leave you with a smooth flat floor.
Once the liquid screed has been pumped in to Laser Leveled Datums it needs 24-48 hours to set, during this time the rooms it has been laid in to should be left sealed up – no open windows or doors.
Try and protect the screed from direct sunlight where possible and importantly protect from frost.
Once 48 hours has passed open the doors and windows to allow a good air flow over the screed.
Anydrite liquid screed drys at a rate of 1mm per day for the first 40mm then 0.5mm per day for the remaining thickness. For example a 50mm slab = 40mm @1mm/day and 10mm @0.5mm/day = 60 days.
Faster Drying Time
After 7 days has passed the underfloor heating can be commissioned and used to force dry the screed. The water temperature should be set to its lowest setting on the mixer valve which is normally around 25d, then run for 3 days at this temperature, after 3 days has passed increase the water temperature via the mixer valve by 5d per day until the design temp has been reach (approx 55d) once at 55d maintain this for 3 days and then repeat the above in reverse.
Before any floor coverings are laid on top make sure the heating is turned off and had time to cool down.
Moisture content in Anhydrite and cement based screeds are critical and should not be overlooked. This should be done before any floor coverings are laid and the responsibility is on the floor fitters to take a moisture reading before fitting any floor coverings.
One useful tool for reading moisture content is a “Air Hygrometer” these tools are not used often these days but provide a reliable indication of the moisture content. Please DO NOT use a wood moisture meter, these will not do the same job!
Before laying tiles or vinyl floor coverings the “latency” needs to be removed from the surface using a suitable Abrading Machine (think of a floor cleaner with wire brush’s attached) this essential scrubs the surface to remove any loose material that would prevent bonded floor coverings adhere to the surface.
Once this has been completed and before the floor covering is installed the screed needs to be primed in conjunction with the floor adhesive best practice. Failure to follow this will result in your floor covering not bonding and coming up!
When purchasing adhesives for your project just ask the supplier if they are suitable for Calcium Sulphate Slab, or Anhydrite/Gyvlon Slab.