Wall (plaster?) material identification before tiling

[PapaDIYstarter]

Hi all,

Newbie here and newbie DIYer trying to update a small shower room on the ground floor. Our plan is to tile all the way around the walls, from floor to ceiling, and box in the boiler.

We’ve hit a bit of a brick wall (photos attached) literally, and we don’t know what material this wall is and/or if we can tile onto it. It looks like concrete with a layer of skim. (The red plaster is where an old window opening has been filled in, so we are assuming this would have been an external wall many years ago). We started clearing up bits of the skim that were flaking off on the left side but the more we do the more it comes off. And it’s left us a bit concerned at the strength of the whole skim layer on the rest of the painted section as well.

We’ve explored the idea of making a new stud wall and tiling onto that instead but when we screw into this wall it is very soft and we can’t get any fixings as the wall crumbles when the wall plugs are knocked in.

Can anyone advise on what it might be or what we should try?

For reference this wall is just a bare wall, it’s not the shower.

Any help is appreciated, and apologies if it’s a stupid question.

Thanks in advance

 

[tell80]

The wall you complain about is a render covered with a gypsum skim - the render was not prepped for the skim but has managed to hold the skim and tile so far!
If you re-tile then the render needs the skim removing, & a proper prepping for adhesive but no skimming - dont skim.
The render is on a background of masonry or stud partition - whichever it is will suggest how to fix things to a solid backing.


You have elec safety issue showing in your pics
- wrapped cables - thats v. bad,
- and cables touching hot pipes - not good
- cables best practice need to be sunk with metal channel covers.
All wet rooms need compliance with Regs.

You need professional eyes on site for proper comments.

 

[JohnD]

anything that is loose or falls off needs to be removed. I think probably long-term dampness in the bathroom has perished gypsum plaster.

when you find out what is behind it you will know whether to render, use a tile backerboard, or something else. If boarding, you might like to include insulation, which will make the room warmer and reduce condensation.

How old is the house? That will give clues of original materials and building techniques. I live in a district where walls are still often rendered with S&C and then a gypsum skim (older houses done in lime). There is also grey gypsum plaster but I don't think that's what you've got.

 

[Nige F]

He's got gypsum bonding/browning with grey siraphite skim. Maybe over celcon blocks. That would explain the soft wall

 

[JohnD]

grey siraphite skim.

haven't seen that in a long time.

 

[PapaDIYstarter]

Thanks for the replies.

The house is 1930s but we think this room was built as part of an extension in the 1980s.

We have persevered and got solid fixings in and put up a new stud which was the easiest option.

Fortunately the electrical cables showing were redundant so we’ve pulled them out now and the boiler connection will be sorted by a professional. The previous owners didn’t have much regard for compliance or safety unfortunately…