anhydrite screed

[tysontile]

hi all,i am tiling 60x60 porcelain tiles onto anhydrite piped underfloor heated floor,it has been laid for over three years,does the floor need sanding first to take primer?thank's tysontile:yikes:

 

[Gazzer]

Yes it will still need prep work the same as a recent floor inc moisture test.

 

[DHTiling]

As above, it will need sanding.. what brand of Anhydrite is it ?, some do have laitence to remove.. and also the ufh should have been commissioned prior to tiling..