Urgent plywood /backer-board advice needed !!!

[Adrian53]

Got a refurbishment job in a shower/WC of a large twin-unit mobile home.
The walls are 2x1 timber covered in 6mm ply and then when converted into a shower topped
with 12mm OSB board and then tiles.
All this has been removed leaving the studding and it's time to add a decent backing for the tiles.

Trouble is the tiles chosen have a fair weight and not sure that the walls can take it if cement boards
are used. Also a double whammy that these homes do flex a bit and cement boards don't.

I've toyed with a few options and come up with this as an idea, so what do you lot think?
1. Beef up the walls with extra studding to create more surface area for boards etc.
2. Use 9mm sealed WBP plywood on walls and 18mm on floor to act as a liner only & tie studding together.
3. Add 10mm STS Professional Foam backing board to wall and floor and tape/seal joints clips etc.

Idea is to create a good waterproof tile-ready surface, but keep weight down as much as posslble.

Comments really welcome ASAP please as need to start on this Friday.

 

[J K Tiling Cornwall]

I think the foam boards over the plywood may be your best bet, fix with adhesive and screw using washers. The plywood will give structural strength 👍

 

[Adrian53]

I think the foam boards over the plywood may be your best bet, fix with adhesive and screw using washers. The plywood will give structural strength 👍

Thank you for that

Confirms what I've thought that it's all about time spent on the studding and ply to
make the structure as sound as possible and then the foam board (fixed as you've
said) will sort he rest.

 

[Adrian53]

Well after beefing-up the studding today, starting to wonder if the plywood liner is needed at all and I could well attach foam board straight to wall.

Any reason why this may be a bad idea?

 

[J K Tiling Cornwall]

No reason why you couldn't put the foam backer boards directly onto the studs. But the only issue might be getting a good fixing on shower screens, shower riser's or any accessories... Ect 👍

 

[Adrian53]

No reason why you couldn't put the foam backer boards directly onto the studs. But the only issue might be getting a good fixing on shower screens, shower riser's or any accessories... Ect 👍

I fixed the studding at 300mm centers to suit the overlap of the backer boards, so it's all
very solid + added extra noggins for accessories etc. so all sorted.

Some of the ply bought from a local timber merchant is showing signs of delaminating
in places, so think abandoning ply was a good choice.

Thanks again for the advice

 

[Rae]

What size tiles

 

[Adrian53]

What size tiles

600mm X 200mm X 10mm