Tanking a shower area against tray

[23vc]

I think most people use rapid set. Or silicone, or even exp foam. I’ve always used mortar, but will probably go rapid set on the next one.

 

[Ivor Windybottom]

I brought mine up to about 2cm below where needed with concrete, then put a carefully floated out layer of strong render. Lots of cement, with half-and-half building and sharp sand. Then plopped the tray on top and shuffled it about, checking with a level in all directions.

The fattest bloke in the world could stand on one leg anywhere in my shower and it wouldn't crack or bend.

 

[Ivor Windybottom]

I reckon you could guarantee failure of the seal if you used expanding foam under it. It's nothing like rigid enough, it would sink eventually.

 

[23vc]

I reckon you could guarantee failure of the seal if you used expanding foam under it. It's nothing like rigid enough, it would sink eventually.

It wouldn’t be my first choice either, but some trays MI’s specify it.

 

[Ollyfp]

I've just read that plaster board adhesive (the powder mix) can be used? IDK!

 

[Ollyfp]

The fattest bloke in the world could stand on one leg anywhere in my shower and it wouldn't crack or bend.

Definitely no need to upload photos of this okay! lol

 

[noseall]

I reckon you could guarantee failure of the seal if you used expanding foam under it. It's nothing like rigid enough, it would sink eventually.

Not necessarily. IMy personal choice is tile adhesive, but I've seen instances where foam has been used beneath a door sill and it hasn't compressed

 

[Ivor Windybottom]

I've just read that plaster board adhesive (the powder mix) can be used? IDK!

Cowboy answer!

I wouldn't want to use anything that's not cement based. Cement undergoes an irreversible chemical reaction when it sets and basically turns into rock. It will even set underwater. However much water you spray on concrete it won't re-dissolve. Plaster will get wet again.

There's a good reason bridges and skyscrapers are made from concrete and not plaster!