Replaster or tile straight over?

[UnusualCapybara]

Just about to try my hand at tiling for the first time and have set about removing our very old bathroom tiles.

The result seems to be that, predictably, the tiles are pulling away the plaster with them exposing the rough wall which is made of what appears to be some sort of sandstone type material.

Clearly it's not smooth and you'd never paint over it but is it worth getting the wall plastered to provide a smooth surface for tiling or can the existing surface be bonded/prepared in some way to tile over?

It's rough as far as surfaces go, but not necessarily uneven.

Untitled

• UnusualCapybara
• 10 Jun 2014
• 1

 

[ree]

Remove all the tile and any loose background.
Bring the rough cover to a plumb and flat surface with bonding or render, and it should be good enough to tile on.

 

[UnusualCapybara]

Many thanks for the reply - have found some areas which are less hopeful so may need to resort to backing board for those.

 

[AdamCH]

Is the yellow stuff solid enough to fix to? If it is then you might be best to overboard with moisture resistant plasterboard and tile onto that.

If it's the foam in the middle of a plasterboard sandwich then not sure what you can do.

 

[ree]

I dont understand where the reference to plaster board comes from - there's certainly none in the pic?

OP, there's no need for backer board - do as suggested above no matter the patches involved. Dont make work for yourself.
Pulling a wall out with BB might give you additional problems.

 

[AdamCH]

Ree - you know that you shouldn't tile onto bonding?

 

[ree]

Why not?

 

[tpt]

AdamCH is right, bonding isn't suitable for tiling onto, render takes donkeys to dry. If the voids are shallow enough, patch them with some floor adhesive, dries very quickly.

 

[AdamCH]

Bonding has very high suction. Can't work out what that yellow surface is - very unlikely to be the sandstone suggested by the OP. Difficult to know what will stick to it without knowing what it is.

 

[ree]

Bonding will "stick to it", (ie. the OP's background) so will a scratch of render. Thats why i suggested them.

"Bonding has very high suction" ... so what?

"bonding isn't suitable for tiling onto" ... why?

"render takes donkeys to dry" ... no it doesn't: two coat work takes 24hrs between coats. Hence, any dubbing out in S&C will be dry next day.
FWIW: In the case above no time factor was mentioned.

"floor adhesive"? I hope that you are referring to cementitious bagged powder adhesive?
The OP has indicated that the area(s) of concern are backer board large. Are you recommending floating the wall(s) in "flooring adhesive"?

AAMOI: "moisture resistant plasterboard" is no more moisture resistant than regular plasterboard - almost zero resistant.

 

[tpt]

Hi ree. tile adhesive will stick to bonding, but all the products we sell state that they should not be used on bonding, its high suction and crumbles too easily and if you check with a manufacturer they will mostly say the same. Render is a great surface, but take days (sometimes weeks) to dry out - i dont mean visually, i mean properly - to get the backing of the manufacturers you can be talking about a week or more.

Yes floor adhesive meant a bagged powder adhesive, and i said for patching IF the areas are shallow enough.

Completely agree about MR plasterboard, it still needs to be tanked and backer board is always better.

Obviously i know that tiling onto render after a day, and tiling directly onto bonding goes on around the world every day, tilers are still painting everything in PVA for some unknown reason - in some cases its fine, in others there are problems, but its best not to go down those routes unless you want to take the risks

 

[ree]

Bonding ceilings and then skimming over is done to probably thousands of square metres every day - i'm not aware of any anecdotal suction or crumbling difficulties.

I personally recall no difficulties, or call backs, when tiling over walls that had been bonded.

Render does not take days or weeks "to dry out".
Damp proofing render or render over previously wet shower walls etc is a different matter. But render applied to dry masonry is good to go in 48 hrs.
There are, of course, other factors such as temperature and common sense to take into account.

All the above is my limited experience, i have no authority in these matters.

 

[AdamCH]

Okay to tile on skimmed bonding but not straight to bonding.