Stud wall in bathroom

[ban-all-sheds]

In the corner of my bathroom I've got what used to be the airing cupboard with hot water cylinder, long gone. So 2 sides of the cupboard are the bathroom walls, the 3rd is a brick wall, tiled on the outside.

I want to extend that wall by 200mm to increase the depth of the cupboard, and have no intention of becoming a bricklayer - it's already got timber at the end which is part of the existing door frame, so timber & boarding will be simple.

So my question - the wall is not next to the bath or shower so won't be getting wet - will ordinary plasterboard be OK for tiling over?

Or what about plywood? I ask because I've got some I could use rather than having to go and buy plasterboard just for 2 narrow strips.

 

[Richard C]

Don’t use ply, it’s a poor choice for a wall tile base & can be unstable; it also has to be WBP rather than standard ply. Even though it’s not a wet area, use Moisture Resistant plasterboard not standard wallboard.

If you just butt strips up the existing brick wall, the biggest problem your likely to get is it will crack due to differential expansion where the two meet. The only real way of avoiding this is build out your extension flush with the existing wall & plasterboard over the entire wall not just the new bit.

 

[ban-all-sheds]

OK - thanks for the advice re ply.

Hadn't thought about differential expansion. B****r.

It it a possibility/probability/certainty?

I'm tempted to take a chance, because to rectify it if I get cracks wouldn't really be any more work than preventing it...

 

[Richard C]

If you were just plastering then I would say a crack where the two meet was a stone bonk certainty. If the tiles overlap the join by any appreciable amount then you may get away with it but there is still a good probability cracks will appear along the nearest grout lines. Only problem with rectification is that the basic problem will still be there & the cracks will be recurring.

Another way of reducing the risk is to remove a 300mm strip of plaster/render from the brick work adjacent to the new stud & rather than just butt up to the existing wall you overlap it with the new strip of PB. Screw the PB to the stud & bond it to the wall with drywall adhesive; reinforce the join with 3 layers of plasterboard tape under the tiles.

 

[ban-all-sheds]

OK -Plan B might work, if I can get a column of tiles off, and if I have enough spare.

The join will be butting up, because at the moment the wall is tiled to the end.

By rectification I meant give in and do what should ideally have been done in the first place, i.e. remove the tiles from that wall, board over all of it and tile.

Which wouldn't be a lot more more work than doing it in the first place - the only effort I'd have wasted would have been cutting and fitting the strip of board and putting up 9 tiles.

The reason I'd like to try the less-than-ideal way first is not so much to avoid having to do the whole of that wall (it's only about 450mm wide at the moment) it's because unless I can still get the tiles (it was done over 6 years ago) then the whole bathroom will need to be re-done.

 

[masona]

I'm wondering if you'll get away with using flexible wall grout mainly for for wide joint 3mm to 20mm which is a polymer modified suitable for slight surface movement, will be a little bit dearer

 

[ban-all-sheds]

Not as dear as retiling an entire room just to be able to extend a wall by 200mm...

Plan Z - I'll face the extended part with opaque perspex with fluorescent tubes inside and call it a lighting feature....