Anhydrite prep for tile
Laitance Removal on Anhydrite Screed
You can't tile straight onto anhydrite. The surface laitance has to go — mechanically.
Anhydrite screeds develop a weak surface layer (laitance) during cure. It has to be removed by mechanical sanding before tile adhesive or resin will bond.
This is the one job on an anhydrite pour that isn't optional.
Laitance removal process
- 1
Wait
Let the screed dry for 5–7 days first — laitance sanding is easier on a partially dry screed.
- 2
Sand
Rotary sander with 40-grit disc across the entire tile area.
- 3
Vacuum
M-class dust extraction — laitance dust is fine and airborne.
- 4
Prime
Manufacturer-approved primer before tile adhesive.
Why installers skip this (and shouldn't)
- It looks like the surface is fine
- Sanding kicks up a lot of dust
- It adds a day to the programme
- The failure is invisible until tile debonds six months later
Frequently asked
Preparing an anhydrite floor for tile?
We can arrange laitance sanding as part of the pour job. Ask up-front.