Surface Preparation after Removing Old Tiles

First of all a big shout out to everyone that contributes to these forums in terms of help and advice - I don't post often but I really appreciate the tips that I've been able to pick up here - if only I had the time and money to put more of them into practice!

Right now I am having a go at re-tiling a guest bathroom and have a fairly basic problem to work on. As you can see from the pics, one wall is plaster skim over PB, the other is plaster over what looks like mortar. Where the skim has come away I am wondering if I can fill the holes and, if so, what with? Should I re-skim? I imagine another option might be to remove the old PB one one wall and re-fit, but there is a problem with this solution because we would like to keep the mirrors that seem to have been glued to the plaster (and if they are not glued, they have some very clever fixing system that I haven't been able to discover!) It's not a question of the work involved in re-boarding, I just don't think it would be possible to remove the mirrors without breaking them.

Unfortunately we want to put a fairly heavy tile up (600x400 porcelain, about 10mm thick) so I am anxious to do everything as much as possible by the book. All advice greatly appreciated.

Reboarding is the best option especially considering the weight of the tiles you are going to use. Mirrors are relatively cheap from a glass supplier so I would replace them. It will probably make it easier to set out the tiling as well, then get a mirror cut to suit the space.

Those tiles would be way to heavy for the substrate you currently have.
I would overboard with 12mm cement boards.....

There isn’t a way to make those walls tillable with those tiles without over boarding. As said, mirrors aren’t expensive to replace. Easiest way is to solid bed 6mm marmox board or equivalent with tile adhesive and mechanical fixings into both the studs and also the solid wall. 12mm board is only needed if your dot and dabbing out, or going direct to studs

pdc said:

Reboarding is the best option especially considering the weight of the tiles you are going to use. Mirrors are relatively cheap from a glass supplier so I would replace them. It will probably make it easier to set out the tiling as well, then get a mirror cut to suit the space.

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+ 1

The plasterboard wall can be cut out and replaced with new, but don't plaster it. That will be cheaper. If the other wall is render you can remove the plaster, and tile direct on that if it's reasonably clean of plaster. If you have the time and not the money. And IMO mirrors are better stuck onto the tiles rather than tiled around. looks more professional.

Thanks all of you - seems pretty clear that some boarding will be required! Having thought about the mirrors I think I can get them off anyway and that will simplify things quite a bit. One further question - for the PB wall, could I attach the marmox to the existing wall, always assuming I can find the existing studs to attach appropriately?

Yes you can

Use the washers with the screws...

You only need the Marmox in the wet areas is the plasterboard around the shower?

pjc said:

You only need the Marmox in the wet areas is the plasterboard around the shower?

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No shower at all in there - it's just loo and washbasin. I was thinking that any tile backing board would be ok, not just marmox.

If your rich. I am not thats why I would use plaster board. And tile on the render.