shower stall tile

Hi there
I have built a shower stall with 19mm wbp plywwod and have tiled it with 10"x8" tiles.
I have two questions should I use grout or silicon in the corners where the tiles meet?
and should I use an admix additive to the grout or seal the grout after it is up ( the grout is water resistant) the stall has three tiled walls and hinged door? I have used silicon between the tile and the shower tray?

 

What is "19mm wbp plywwod "? I hope this is not plywood. Tile in a shower stall should be attached to a cement backer board. Failure to do so can result in premature failure, because grout is neither designed nor intended to be waterproof.

Use silicone caulk for the seams where adjacent walls meet.

Seal the grout with a vapor permissive sealer.

 

Perkins

MusicField is right concrete backer board is the right stuff. Over time as water seeps behind the tile, the plywood will expand and contract as it absorbs mosture.

This will cause cracked grout and loose tiles. Since it sounds like you already have it up, do any thing you can to prevent water from seeping in.

Use the additive AND seal the grout. I would recomend re-grouting every 2 or 3 years weather you think it needs it or not.

Use sillicone in all corner, including where the wall meets the floor.

I'm a little hesitant to ask how you installed the floor, the steps should be;

1 layer of roofing paper
1 layer wire mesh
layer of morter 1.5 - 2 inch thick
rubber / pvc membrain (ussually 40mm)
layer of morter 1.5 - 2 inch thick
Tile
grout
seal

 

thanks guys the floor is a stone resin tray wbp is waterproof and boilproof plywood ( exterior grade ply).

cant buy concrete backer board in ireland.
wbp is what everyone uses.
the guy that supplied the tile is a professional tiler and he says there is no need for the admix in the grout unless its in a swimming pool.
but I think ill use it anyway.