TIling substrate to cover adjacent wood frame and brickwork

[rivergo1d]

Hi all
My shower room has a fake wall for the shower equipment, whose surface lines up level with the window recess shown on the left. In the original bathroom the thin white tiles had cracked where the frame met the window. The frame had been covered in thin board, and the window recess in plaster.

I have hacked back the window recess plaster and am about to fit 12mm aquapanel to straddle the two (flush) areas, hopefully to give a solid surface for tiling. I had been planning on screwing into the frame, and applying a few dot and dabs plus fixings into the window recess area. The recess area is just 100 x 17 cm.

However, I am concerned that the same stresses which cracked the original tiles will also crack the cement board, and then the tiles. Can anyone suggest anything better? eg....
1. Some kind of flexible dot/dab method?
2. Because the area is so small, just frame fix into a "high spot" of the brickwork without any dot/dab at all
3. Some other substrate, such as 12mm plywood and then good tanking? Seems a bit risky for a shower area ... though it is the wall of the shower holding the equipment, so dryest?
4. A thin layer of 4mm plywood between the frame/wall and the aquapanel? I suppose the panel still has to fix into the wall below.

NB. The tiles I'm using are 60x30 cm porcelain, 8mm thick, about 25Kg/m2 including grout and adhesive.

You can see that I am limited in terms of substrate thickness because it eats into the window surround area and will look "less odd" the thinner I keep it.

Thanks for any advice ...
Rich

Untitled

• rivergo1d
• 18 Jul 2011
• 1

 

[Richard C]

I have hacked back the window recess plaster and am about to fit 12mm aquapanel to straddle the two (flush) areas, hopefully to give a solid surface for tiling. I had been planning on screwing into the frame, and applying a few dot and dabs plus fixings into the window recess area. The recess area is just 100 x 17 cm.

However, I am concerned that the same stresses which cracked the original tiles will also crack the cement board, and then the tiles. Can anyone suggest anything better?

That’s how I would do it; keep the board as large as possible so the bit that goes into the reveal would be more or less self supporting. It’s so small & with no load, I would be inclined just to use adhesive dabs or even silicone to locate the board in the window reveal without any fixings, that way if you get any movement the board wont crack but I think that’s unlikely in any case. Use a silicone bead rather then grout on the finished tiling where the stud meets the wall, inside & around the window reveal.

1. Some kind of flexible dot/dab method?

2. Because the area is so small, just frame fix into a "high spot" of the brickwork without any dot/dab at all

As above

3. Some other substrate, such as 12mm plywood and then good tanking? Seems a bit risky for a shower area ... though it is the wall of the shower holding the equipment, so dryest?

4. A thin layer of 4mm plywood between the frame/wall and the aquapanel? I suppose the panel still has to fix into the wall below.

Don’t use ply as a tile base on walls, especially in a wet area.

NB. The tiles I'm using are 60x30 cm porcelain, 8mm thick, about 25Kg/m2 including grout and adhesive.

It seems like you’ve done some homework but if you haven’t already done so, read the Tiling Forum Sticky & Archive posts it may prevent you making potentially disastrous & expensive mistakes. Use only quality trade adhesive & grout of the correct type for your tiles & tile base, BAL Webber, Granfix, Mapei (but not the stuff in BNQ) etc. cheap own brand & DIY products are mostly crap. Powder cement only for that size tile & I assume your aware of the 20 kg/sqm weight restrictions of plaster!

An observation; personally I would never use push fit behind a shower wall, let alone plastic push fit. I may be a luddite when it comes to plumbing but for me, it's bent/soldered copper all the way with as few fittings as possible.

 

[rivergo1d]

Thanks as always Richard. Is there any particular silicone you'd recommend as being suitable for aquapanel / brickwork in a bathroom? I like the idea of this as it will give it enough flexibility for me to feel safe!

Oh - one question about large pieces of board - I can either lay board across the entire width of that fake wall, but with a join horizontally (including into the window area), or I can make the window area continuous and have a vertical join far away at the other end of the fake well. I guess your suggestion would be for the latter?

Agree about pushfit in many ways, but with all the screw-in terminals into my shower mixer and the desire for a little extra bendability in the pipes I decided pushfit would be the easiest way forward in terms of quick-disconnect, tighten, reconnect without any potential for "unscrewing" when tightening up an adjacent compression joint. If things do go wrong I can get at the pipework by hacking in from the other side of the wall, albeit with a little repairing but at least not retiling my new bathroom.

 

[Richard C]

Is there any particular silicone you'd recommend as being suitable for aquapanel / brickwork in a bathroom?

Use a low modulus building silicone on the Aquapanel & a quality anti-fungal sanitary silicone sealer for the beading down the tiled corner of the shower & window reveal.

Oh - one question about large pieces of board - I can either lay board across the entire width of that fake wall, but with a join horizontally (including into the window area), or I can make the window area continuous and have a vertical join far away at the other end of the fake well. I guess your suggestion would be for the latter?

Yes.