Substrate prep

[Lawrence147]

Hi Guys

Haven't been here for a while but working hard , very busy and always learning, both out there and on here. As usual, I can only dream about emulating your high standards on jobs on here

Am currently doing a bathroom refurb for friends - am tiling a victorian tenement flat - a long and narrow bathroom which comprises a sink and bath in one area, leading to a toilet under a window in a separate area at the end.

The areas to be tiled are the sink splashback to the floor, the opposite shower area 2 mtrs x 1.6 mtrs and the toilet back board in addition to the floor. The rest is being papered and painted.

I have cement boards for screwing to the floorboards for 600 square porcelains, 305 x 305 Natural Stone field tiles (last boxes to be sealed tomorrow) powdered Weber addy and SBR for all areas and Mapei White addy for the 3 vertical mosaics I'm putting on the 3 wall areas. Shower area will also be tanked.

My problem is the substrate - the render behind the plaster around the bath is loose in several areas due to the age of the prop and the last time any improvement was done in this room. To give you an idea, tonight I removed 10mm quartered ceramic 'beading' from the wall side on the bath - I don't think that's a new idea!

I don't want to rip these areas out as the affected render is not, as far as I can see, over the whole wall, I've already papered so the mess would put me back days and this wall looks as if it's been rendered and plastered too many times so I think I would have to move the bath, frame and plumbing to keep it tight to the wall. I feel as if I'm opening a can of worms here.

In my research, I found a solution involving drilling holes around the affected areas and sinking PVA behind the plaster but know that's not a safe option here.

Can I overboard with 12mm P/B with glue and larger rawl plug fixings that will grip the brickwork behind ensuring a safer substrate for tiling? Obviously, I don't want my friends (or any cust for that matter) being knocked out or worse from a tile fixed to this failing substrate.

Can any of you pro's advise on this or any of my plans for this job that I've described above

Many thanks in advance.

Lawrence

 

[Dan]

Loved the old ceramic beading! Used to sell shed loads of it years ago. haha

If plaster and render is falling off, all the loose needs chipping off really. You can then perhaps use plasterboard adhesive or even rapid set adhesive to patchup if it's just small areas affected. Though if a lot comes off it's questionable as to whether it should have all been taken off first maybe.

If you overboard and screw to the brickwork, that'd suggest you'd be fine tiling to the backer board as that'd be secure. Though I'd try and chip off what's falling off already and see how much it actually is.

You might find it's just all around the bath due to water getting in there every time the bath is used etc and that above that area is fine. In which case just patch it up and tile it.

 

[Lawrence147]

Dan, I agree that I need to chip away the loose bits before boarding however the backer is for the floor, which brings me to another question. Am I right in saying, as I've been taught, that when I board I'm ok with just priming and tanking before the tiles go up?

Lawrence