How To Tile Over Spray Foam That Has Not Set Hard

[Toby]

My plumber has just finished the pipework into a drain in a new utility. He said he would put down some board but instead has half-filled a cavity with foam. But the foam has not dried hard it has dried soft.

Originally I envisaged using self leveling compound but I can't lay this on soft foam. Wondering what the best approach will be.

I boxed the open drain off when applying self leveling to the rest of the floor. The foam is 1 to 2 inches below screed surface. I then have around 10mm where leveling compound and tiling adhesive sits under adjacent tiles.

The tiles are 60cm x 30cm. The 2 tiles that will cover the drain area will both have screed floor under most of the tile but the corners will be over the drain.

At this point I'm thinking of removing the foam. Or laying thin plywood over the drain and tiling over that.

 

[Dumbo]

Remove the foam and fill in with a thick bed levelling compound

 

[Dave]

As above , remove as much as you can and level.

 

[Old Mod]

Yes definitely remove it, don’t use ply, it’s bound to rot out at some point.

 

[Toby]

Thanks for responses. I took some of the foam out then covered with pre-mix concrete. This has set well. I'll now use SLC and tile over that. This will be under about 25% of non load bearing part of tile as it's right up against the wall so hopefully will be fine.

 

[Old Mod]

Thanks for coming back to us, appreciate that.