Tiling a rough plastered stone wall in cottage.

[Jastsa]

I have a stone cottage circa 1870, that is rough plastered internally. I want to tile two internal walls in the bathroom. The walls are 2m wide by 2m high approx, so only a small square room (if you can call anything square in an old cottage). One wall is just a partition wall between the kitchen and bathroom which is already partially tiled and will be fine, the other is the stone wall between my cottage and my neighbours cottage which is also currently tiled about 1/3 of the way along from the internal corner.
Because this wall is rough plastered, I would need to board over it to give a flat surface to tile onto.
The external wall and the other stone wall between the bathroom and hallway will remain rough plastered.
I am thinking of using thermal board, but is this the best option?
There is currently no damp in the cottage anywhere, so I feel very fortunate and believe this is due to the walls being lime plastered, and I think it is the original plaster from 1870.
My neighbour had the same rough plaster on her walls, didn’t like it, had it smooth plastered over. She now has terrible damp issues on all external walls. We are leaving ours well alone other than repainting with breathable paint.
Thank you for you help.

 

[stuart45]

How rough is the wall?. Before adhesives came in we used to tile walls using mortar on the back. Originally lime mortar, and later cement mortar. You can tile some quite rough walls by adjusting the amount of mortar on the back of the tiles. You do need to soak the tiles first though.
It is a bit more difficult than using tile adhesive and a notched trowel on a flat surface though.

 

[Jastsa]

How rough is the wall?. Before adhesives came in we used to tile walls using mortar on the back. Originally lime mortar, and later cement mortar. You can tile some quite rough walls by adjusting the amount of mortar on the back of the tiles. You do need to soak the tiles first though.
It is a bit more difficult than using tile adhesive and a notched trowel on a flat surface though.

Thank you. The rough plaster is deeply rough. It isn’t just thin on the surface. . I am also concerned about breathability of the wall behind the tiles. I am thinking a board on batons to create a small space like a cavity wall behind the board and tiles. Wondering if this would be the best way and what board is best.

 

[Cubist]

It's pointless worrying about the breathability of a wall over which you intend to apply ceramic tiles. The tiles themselves will be throughly impermeable. If this is an external wall the best you can do is to limit the tiled area to the smallest possible or ensure that you have suitable air extractors in use whenever the bathroom is occupied.

 

[Jastsa]

It's pointless worrying about the breathability of a wall over which you intend to apply ceramic tiles. The tiles themselves will be throughly impermeable. If this is an external wall the best you can do is to limit the tiled area to the smallest possible or ensure that you have suitable air extractors in use whenever the bathroom is occupied.

Thank you. It’s an internal wall. If the wall is boarded first and a small gap is left between the wall and the board with tiles on, wouldn’t the wall still be able to get some air around it? I don’t intend to tile directly to the wall.

 

[Cubist]

Theres little need to worry about breathability of purely internal walls provided that air circulates effectively around them. The concern for breathability is associated with walls that have an indoor AND outdoor exposure.

 

[Jastsa]

 

[Jastsa]

This is the plaster on the wall. It isn’t Artex, it is plaster. I think it is original to the cottage.

 

[Jastsa]

Theres little need to worry about breathability of purely internal walls provided that air circulates effectively around them. The concern for breathability is associated with walls that have an indoor AND outdoor exposure.

Thank you.

 

[Cubist]

Assuming the wall you want to tile is plaster you might try to first sand off the peaks to achieve a generally flat surface. Messy but it can be done and you'll then find fixing the tiles easier.

 

[Jastsa]

Thank you for your help so far, I do appreciate it.