Tiling Over Plywood, Slightly Confused.com

[Casper]

Hi
I have to tile over plywood boxed in pipes and will be using Bal one part flexible adhesive. The instructions state for timber flooring you should overlay with exterior ply and prime all timber surfaces on back face and edges with neat BAL BOND SBR priming agent. So my question is why do you have to prime the back face of plywood which will not be tiled and does that mean that I do not have to prime the front face which will be tiled.

 

[Andy Allen]

I would just overboard the ply with plasterboard or cement board then tile.
I personally hate tiling on wood.

 

[Rich Midge]

Hi
I have to tile over plywood boxed in pipes and will be using Bal one part flexible adhesive. The instructions state for timber flooring you should overlay with exterior ply and prime all timber surfaces on back face and edges with neat BAL BOND SBR priming agent. So my question is why do you have to prime the back face of plywood which will not be tiled and does that mean that I do not have to prime the front face which will be tiled.

You're trying to prevent moisture ingress and therefore subsequent warping or swelling etc. As Andy said, it's always preferable to avoid fixing to ply nowadays if you can. As for priming the face you're going to tile, personally, i always do. Imo it kills any dust, prevents the addy drying too quick and increases bond strength.

 

[Old Mod]

That's back, (comma) face, and edges!
Basically dip it in SBR.
But as Andy says, if u have opportunity board it or replace it with something more suitable, then do that.
There are far better materials to use when it comes to tiling.
The reason u prime all surfaces when using ply is to help prevent against moisture ingress.
Which means it will be less likely to deform (expand and contract) or delaminate.

 

[Old Mod]

You're trying to prevent moisture ingress and therefore subsequent warping or swelling etc. As Andy said, it's always preferable to avoid fixing to ply nowadays if you can. As for priming the face you're going to tile, personally, i always do. Imo it kills any dust, prevents the addy drying too quick and increases bond strength.

Haha "snap!"

 

[Casper]

Thanks for all your replies. If I use cement board should I remove the ply first or fix over the top and what thickness cement board should be used.

 

[Old Mod]

Overboard with 6mm or
Straight to frame with 12mm

 

[On one]

I think the idea of priming the back and sides of plywood with SBR(waterproof) is to stop any ambient moisture penetration(over some years) from behind??

 

[White Room]

Nothing worse than moisture from behind

 

[Casper]

Thanks for all of your advice and have now fitted 6mm marmox multiboard over the plywood. Does this require priming with BAL SBR before tiling.