Anhydrite (calcium sulphate) screed

A flowing screed made with a calcium sulphate binder instead of cement, often laid over underfloor heating.

It must be very dry before tiling, its surface skin (laitance) has to be removed, and it needs a primer before a cement-based adhesive. Without the primer the two can react and lose their bond.

Follow the screed maker's and adhesive maker's instructions together.