What is this render on my walls and how might I be rid of it

[doogyscoot]

Basically as a follow on from my question about skimming tongue & groove ceilings... the whole bathroom was clad in tongue and groove. I have begun to strip it all away as part of a total bathroom refurb. Under the newer T&G were a few things.
From the floor to about 150cm up the wall was possibly original wooden t&g cladding (this is a 107 year old building) under which were two finishes.

From the floor up to just about 100cm is bare brick.

From there up to where the old wood cladding terminated is some kind of rough render, dark grey and sandy/chalky when removed though quite hard and of varying thickness from verythin to about 15-20mm in places.

Above where the old wood cladding was is a smooth flat render (under the horrible old blue wallpaper in the first pic) which is hard to touch, slightly rough and white in colour, this seems to have been applied over another darker greyish render, possibly the same as the aforementioned stuff. This finish goes to the ceiling. Both renders seem to have very fine fibres/hairs through them.

Basically because this is a smallish room I would ideally like to remove this render back to brick as it will win me back just enough space to install a 900mm quadrant shower rather than an 800mm.
Any ideas what this render is? I'm presuming just old plaster but either way would it be a reasonable proposition to remove this back to the brickwork?
If I do so would the best tool for the job be an SDS drill with wide chisel bit?
I was thinking on getting back to brick, at least on the two walls touched by the shower, then dot & dabbing 12.5mm drywall on, with 12.5mm in the 900mm sections of the walls covered by the shower enclosure, the area I talk about is in the first pic.

Any thoughts on how to deal with this and then refinish the walls would be appreciated!

 

[marshman]

sounds like lime mortar, best tool to remove is hatchet, just start at the bottom and chop at a angle.

 

[trowelmonkey1]

you can use an SDS chisel BUT if it's well stuck to the wall you can damage the brickwork if you're not careful, have a go at it with a bolster and lump hammer or a hatchet like marshy said.

if this is going to have a shower or bath against it when finished i'd use tilebacker/aquapanel and not standard board.

 

[Richard C]

As advised by TM, don’t use standard wall board, only use MR board in bath/shower rooms. Tank MR board in wet areas if you want it to last but far better to use a waterproof tile backer board.

 

[doogyscoot]

Just re-read my post and noticed I omitted to say that the shower area will be done with 12.5mm aquapanel or similar...
Is Aquapanel suitable for dot-dabbing onto brickwork?
I would like to allow a space for the wall to ventilate but wasn't sure how thin you can go with straps so dot and dab seemed the best solution given the wall won't be perfectly flat I suppose.

 

[Richard C]

Is Aquapanel suitable for dot-dabbing onto brickwork?

Knauf say no, presumably because of the weight but I & many others do this by adding additional mechanical fixings. Make sure you know where the adhesive dabs will be by using a uniform pattern, fix the boards to the wall, level up & lave overnight for the adhesive to dry & fix with screws through the adhesive dabs into the wall behind; it’s Important you fix through the adhesive dabs or you’ll distort & most likely crack the board when tightening them up. Easiest way is to use through frame fixings (with a captive plug) from the front, it will avoid having to pre-drill the wall & fix plugs which you’ll never get to line up. Alternatively use Marmox backer boards which can be fixed with tile adhesive or screws.

As before, I would advise you use MR boards rather than standard wall board; you can tile straight onto it but if it’s to be plastered, it must be primed first. Have a read of the Tiling forum sticky & archive posts before you do any tiling, it could avoid you making costly & potentially disastrous mistakes. Only use quality trade adhesive/grout suitable for the tiles you chose & avoid chepo DIY products.

 

[doogyscoot]

Thanks again Richard, I've done a fair bit of reading about tiling and feel that it is something I should be able to do without too much bother.

I started tearing off the old render, it is just over an inch thick in some places but I've found that if I saw squares into it with a pad-saw I can knock it off with a few blows froma claw hammer and a minimum of scraping. The brick work underneath seems fairly sound, at least none of it is coming away with the render... It's making ahellish mess though, any suugestions on how to make it easier to tidy up? Just put sheets down over the whole floor I suppose?

My concerns about what to sheet with are all revolving around a little annoyance which is the fact the on one wall I need to be as close to the brick as possible for the shower tray to fit in, as it is it will slightly overlap with the door frame architrave but I'm not adverse to just removing the architrave and sheeting up to the edge of the door itself.
To get close I fugure the best way is to d&d but this will be more troublesome with aquapanel I suspect so I am swaying towards sheeting with 12.5m wallboard then tanking.
Ideally I would use MR board for the whole room but this is not feasible because I am ging to D&D all the board for extra space and I know you cannot D&D MR board... Our bathroom never gets that wet so I'm sure the rest of the room will be fine without MR board and mabe just have it tiled over.

I think I'm going to post this in the projects page as it has gone from something I was going to do bits of and get trades in for the rest to something I will probably just try and get done by myself.

 

[Richard C]

Ideally I would use MR board for the whole room but this is not feasible because I am ging to D&D all the board for extra space and I know you cannot D&D MR board.

Who told you that, that’s not right!

 

[doogyscoot]

Ideally I would use MR board for the whole room but this is not feasible because I am ging to D&D all the board for extra space and I know you cannot D&D MR board.

Who told you that, that’s not right!

Really? I thought you could not use drywall adhesive on moisture resistant board because of the foil backing?

 

[Richard C]

Really? I thought you could not use drywall adhesive on moisture resistant board because of the foil backing?

Your getting your boards mixed up; its Duplex Wallboard board that has a vapour control foil back membrane & grey face & can’t be D&D’d but it’s no more resistant to moisture in a bathroom than standard wallboard. Moisture Resistant board has green facings & can be D&D’d, it has a moisture resistant additive in the linings & Gypsum core but should still be tanked in wet areas.

 

[doogyscoot]

Really? I thought you could not use drywall adhesive on moisture resistant board because of the foil backing?

Your getting your boards mixed up; its Duplex Wallboard board that has a vapour control foil back membrane & grey face & can’t be D&D’d but it’s no more resistant to moisture in a bathroom than standard wallboard. Moisture Resistant board has green facings & can be D&D’d, it has a moisture resistant additive in the linings & Gypsum core but should still be tanked in wet areas.

Ahhh! Good to know, I will look out for those then. Does D&D leave any space on the back of the board for ventilation so any damp does not get through?

 

[Richard C]

Does D&D leave any space on the back of the board

Depends how close you board it.

for ventilation so any damp does not get through?

If you’ve got damp penetration problems (from the outside) then leaving a gap for “ventilation” behind D&D boards is definitely not the way to go. It won’t cure it, it will fester behind there & most likely your boards will fall off the wall eventually. Duplex boards will cope better but now your talking battening & breathable membranes; you need to do far more than space the boards off the wall to cure penetrating damp.

 

[doogyscoot]

Does D&D leave any space on the back of the board

Depends how close you board it.

for ventilation so any damp does not get through?

If you’ve got damp penetration problems (from the outside) then leaving a gap for “ventilation” behind D&D boards is definitely not the way to go. It won’t cure it, it will fester behind there & most likely your boards will fall off the wall eventually. Duplex boards will cope better but now your talking battening & breathable membranes; you need to do far more than space the boards off the wall to cure penetrating damp.

To be fair, it should be ok, All walls are internal bar one small wall and it is a pretty thick well clad external wall. That one can be battened anyway. All the rest have a good height of about 3 feet before they meet the ground and the underfloor area is well vented.
The render I am knocking off seems totally dry as does the wall.