keying/pva before or after tanking?

[gimchee]

Hello - plan to tile over newly skimmed bathroom walls. I didn't know how important it is to tank the walls in the shower area. But I now know why the plaster had blown previously. Anyhow, should the walls be mechanically keyed before tanking, or should pva be applied to the walls after tanking, or neither?

Tony

 

[Jasonb]

No need for mechanical key. Don't use PVA but get the correct primer for the tanking you are going to use. BAl & Dunlop both do a kit that includes the primer.

Also check the combined weight of tiles & adhesive to make sure the skimmed walls can take it.

Jason

 

[gimchee]

Thanks Jason. Anyone know how to work out the permissable weight that newly skimmed walls can carry?

Tony

 

[Jasonb]

Weigh 2 or 3 tiles them work out how many to a square meter and add 3-4kg to that total for the weight of adhesive. Another way is to put a box of tiles on your weighing scales as most boxes are 1m2 of tiles.

Skimmed walls will only take 20kg tile adhesive, 32kg for bare plasterboard and 50kg if you go for Aquapanel.

Jason

 

[gimchee]

Jason - Thanks for the information.

Tony