Thickening a wall with two different types of walls behind

BenDen · Apr 30, 2024 1:03 am

Hi all.

Thinking of renovating the bathroom and getting a concealed cistern installed. Cistern itself is 80mm deep and will be installed in the same location as the current toilet. However, there is only a 45mm clearance within that wall as the plaster is mounted onto suspended ceiling rails, which are mounted onto the cinder blocks, at least in that section of the wall.

To increase this clearance, I'm thinking of putting in a stud wall so that the finished studs are 90mm from the cinder blocks using 70mm studs with a 20mm gap for insulation/moisture prevention with the new wall spanning the whole wall (red line) and being joined at the abutting stud walls as well as the shared stud wall with the living room. Ideally this would give me the 90mm I need for the plumber to install a concealed cistern with the 10mm of play.

But this doesn't account for the discrepancy there will be if I have to put studs on studs (living room wall) as it will create too small of a setout for the S trap of the new loo as it'll bring out the wall even more than intended.

So far I've only opened the wall enough to see the drawn parts but can get more info if needed.
I'm sure there are better approaches than this one, so please let me know.

Cheers

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renovator_me · May 04, 2024 12:53 pm

I might be misunderstanding.... but I would be more inclined to cut a section out from the cinder block wall and place the cistern in the cinder block wall. Very messy job especially if it is core filled with concrete but easier than building a stud wall out. You should only need to cut 40mm into the cinder block wall. Not too difficult with an angle grinder.

Depending on current plumbing location you would possibly then need to chase the plumbing down the wall or just run it between the cinder block and gyprock where the styro insulation is.

However you would need to consider if the waterproofing would be compromised and would need to be redone.