calcium sulphate

[smartile]

:mad2:Hi everyone. Need some helpful advice if anyone knows. it has been recommended when tiling onto calcium sulphate top screed over underfloor heating that this should be primed then treated with 2 coats of wet room paste to act as a de-coupling membrane. Apparently there have been many problems when tiling on this screed as adhesive fails to bond directly to it. Does anyone have any answers to this or had problems of this nature? cheers. Martin

 

[grumpygrouter]

Use a decoupling membrane like Durabase or Ditra matting. Drop Wetdecs, one of our sponsors a PM and ask his advice.

 

[GazTech]

With these types of screeds, it is recommended that the top or weak layer is removed. If you can't do this, then Tiler @ wetdecs will give you matting instructions as an alternative.....Gaz

 

[smartile]

Thanx guys. It seems to be a common problem that alot of builders are not aware of. I've heard of atleast 3 properties in the last year where tiles hav lifted clean away. My local tile shop gave me Granfix's recommendation of 2coats neat acrylic primer then 2 coats of their wetroom paste then another coat of neat primer before tiling...this I hav done on smaller areas and seems to be succesful but Im now quoting for a job nearly 70m2 on the stuff and wondered if there was a easier/more economical solution?