What is this surface and can I tile directly onto it

[dylanswall]

I have removed the tiles from my bathroom and some of the plaster has come away to reveal this rough, black surface. Just wondering if anyone knows what it is and whether I can tile directly onto it (if I tank it first)

the mystery surface material

• dylanswall
• 30 Dec 2008
• 1

 

[gcol]

I'm assuming it's in sheet form and it's a stud wall - how thick is the sheet? It's hard to tell, but if it's a sheet and not too thick, it could be asbestos I suppose. Does it look like it's made up of strands?

 

[dylanswall]

Asbestos you say? My sphincter has suddenly contracted.

Yeah, it is in sheet form (i.e. not made up of bricks). Is is quite thick as I have pulled out wall plugs from it and they don't go straight through it.

When the wall plugs are pulled out they come out easily (and leave a large hole) so it isn't the strongest material.

 

[gcol]

Asbestos wouldn't normally be that thick. Could just be old plasterboard that has been painted with bitumen or such like.
PVA the areas where the plaster has come away, skim over with multi finish plaster or one coat plaster, tank the walls then tile. Alternatively, overboard with plasterboard, tank then tile.

 

[dylanswall]

I thought about plasterboarding the whole thing, unfortunately that encroaches in on the edge of the bath a bit, but is going to be the easiest way. Cheers for the help.