Plywood for Wetroom subfloor

[djkprojects]

Hello guys,

I'll be converting one of my upstairs bedrooms into an en-suite/wetroom and I want to replace th existing floorboards with plywood but struggling to figure out which type I need. I understand that it should be hardwood plywood which is at least EN 636-2 and EN314-2 Class 2 compliant but then does it need to be structural. Looking through different websites from Wickes to Travis Perkins but they all name the sheets differently and add to the confusion e.g. Wickes say Non-Structural Hardwood Plywood but it does comply with EN 636-2 and EN314-2 Class 2 (what used to be WBP).

Can you please advise what type do you normally buy for wetrooms?

Thank you

 

[Tile Marble Granite]

Any 18mm plywood would work, whatever is most cost effective for you. I used them all no problem.

 

[bsc ceramics]

But you cant tile straight onto the plywood

 

[djkprojects]

I can't tile on plywood on walls but it's fine on floors + I'll be using ditra UFH membrane

 

[bsc ceramics]

you cant tile straight onto plywood. ok as your using a mat

 

[djkprojects]

Yes, I will be using matting but can you please explain why I can't tile directly onto plywood. That's how people have done it for years and no issues. In my friends two ensuites plywood floor were tiled onto directly few years ago and not a single crack on the grout, tiles or loose tiles etc. The lavatories in the office I work in central London have plywood half walls tiled directly onto. Surely, as it's a commercial building with hundreds of people using them, it wouldn't be allowed if it was unsuitable?

 

[bsc ceramics]

yes i know i have done the same for years but for some reason maybe after a few
failed british standards now say you should not tile directly onto any type of wood.
i dont think i ever had one fail but now if one does its because its onto wood,
Thats what they would say.

 

[djkprojects]

I think people misread the BS. It only mentions tiling on plywood walls due to potential risk of plywood delaminating and tiles dropping on your head but there is no mention of plywood floors unless I’ve missed that section which I’m pretty sure havent.

 

[bsc ceramics]

It includes floors I think the wording is all areas.
Any tiler worth anything will tell you. That's why there's products like tile backer board and ditra and the many others on the market

 

[Steve6690]

For a wetroom floor I might use ply for noggins but overboard with something more appropriate. The wetroom I'm currently doing is using that approach.

 

[djkprojects]

It includes floors I think the wording is all areas.
Any tiler worth anything will tell you. That's why there's products like tile backer board and ditra and the many others on the market

Funny you mention Ditra, look at this cross section I was given by… Schluter UK.

 

[bsc ceramics]

meaning what? i dont understand

 

[Ben-gee]

It includes floors I think the wording is all areas.
Any tiler worth anything will tell you. That's why there's products like tile backer board and ditra and the many others on the market

I think you’ve actually got that the wrong way around!
Because there are products like tile backer etc - they have changed the standards so you are forced to use their expensive products… as you say in previous post, you’ve never had a failure on ply!

 

[bsc ceramics]

but it is british standard

 

[djkprojects]

but it is british standard

Plywood Walls - BS 5385-1:2018

Direct Tiling to Plywood Walls
Direct fixing of tiles to walls constructed from plywood is not recommended in BS 5385-1: 2018 Clause 6.1.2.7 Other sheets and boards (see also 6.2.3.3) “The use of sheets or boards that are subject to movement from changes in moisture content should be avoided. Plywood and other wood-based sheets or boards should not be used for direct tiling”

 

[bsc ceramics]

and its the same for floors why would it not be?
im not wasting any more time on this tread any tiler worth his trade would not tile on a wood floor
Iv been tiling many many years and for me its belt and braces ever time.
some people work in offices some of us dont.

 

[djkprojects]

and its the same for floors why would it not be?
im not wasting any more time on this tread any tiler worth his trade would not tile on a wood floor
Iv been tiling many many years and for me its belt and braces ever time.
some people work in offices some of us dont.

because there is no risk of tile falling off on your head when it's on the floor, that's the difference. The BS have changed not because plywood is not good to tile on but because the quality of some of the imports isn't good and because of the popularity of backerboards. As you said you've been tiling on plywood for years and had no issues so I guess the only reason why you decided to use backerboard is because BS say so. Please also note that BS are for guidance and recommendations, not what you must or mustn't do.

 

[John P]

because there is no risk of tile falling off on your head when it's on the floor, that's the difference. The BS have changed not because plywood is not good to tile on but because the quality of some of the imports isn't good and because of the popularity of backerboards. As you said you've been tiling on plywood for years and had no issues so I guess the only reason why you decided to use backerboard is because BS say so. Please also note that BS are for guidance and recommendations, not what you must or mustn't do.

The main reason British Standards exist is that they present guidance in a way that IF a failed job does get to litigation,
then it is a very simple question for a lawyer to ask: 'why didn't you follow the guidance in the Standard?'
'I didn't need to' isn't convincing, if the failure is apparent.
Tiles (and adhesive) do not expand or contract as they don't absorb water.
Plywood does.