Plywood on shower walls?

[indus]

Hi

I'm having the en suites in my loft conversion finished and the builder has just used 'external plywood' on the walls. Tiling will then go straight on.

Is this ok for waterproofing or should something else be done?

Thanks

 

[gcol]

Wouldn't be happy about that myself. You want to see how water affects exterior ply, leave a piece outside for a week.
Around a shower you'll want to be tanking the walls - google "bal wp1". You can apply it to ply. I'd have just plasterboarded it and tanked the areas subject to water.

 

[Richard C]

I'm having the en suites in my loft conversion finished and the builder has just used 'external plywood' on the walls. Tiling will then go straight on.

I wouldn’t advise that, it’s a very outdated & old fashioned approach. WBP ply is not a good tile base for walls even if the tile base is tanked, more so in a loft conversion which could potentially have a cold/damp side. Ply (wood) is dimensionally unstable when exposed to moisture, even if the back side is sealed, if moisture gets in your tiles will fail. Insist on a decent waterproof, 12mm tile backer board instead, the cost difference over WBP is negligible but it will remain dimensionally stable even if totally immersed & you can tile straight onto it.