Tiling Advice Needed ….. Tiling over poor/uneven plaster

For some strange reason, Ive decided to re-tile my bathroom. After knocking off a load of the old ones, the state of the plaster underneath is pretty poor….. the skim(?) layer has bubbled and peeling off.

Is it worth making the wall better before tiling? Or, since i’m sticking tiles on, just leave it, and use more adhesive to even it out??

is it a wet area like a shower?

How about take off the plaster board and attach some hardibacker (waterproof cementous board), a coat of PVA, then you can tile directly on to it with a voidless waterproof adhesive layer.

If its just a back splash to a sink, sod it, use a good splodge of stiff mix adhesive and a straight edge to keep a flat plane.

If it was me, I’d get it skimmed before tiling…. or get a man in to tile over the existing surface. Depending on the area, condition etc, costs may work out to be about the same either way.

DO NOT under any circumstances use PVA as a tile primer.
Tile adhesive is water resistant, but not water proof. The water will find it’s way to the PVA, once this happens it will become liquid again and come away.

To do it properly, I need more info to advise you properly.
Where are the tiles going, bath or shower area?
Is the remaining skim very solid, it needs to be really. If not, pull it all off using a scraper or equivalent.
What size and thickness of tiles are you fixing? Are they ceramic or porcalain/stone?
Finally, what pattern are you doing? If brick type pattern, the wall really needs to be super flat, unless you’re a pro, even then it’s extremely hard to get it perfect if not totally flat.

Usually you an get away with filling the patches with tile adhesive, not the tubbed ready mix stuff though. Proper cement powdered stuff. Rapid or normal set. Get decent stuff like weber or mapei, bal is way over priced for what it is and no better than weber.

well there you go, learn something new everyday.
http://www.ultimatehandyman.co.uk/tiling/diy_Tiling_Why_not_to_use_pva.htm

as it happens we didnt use PVA on our hardibacker, it was only mentioned to me later as a method.

Should be using either sbr, acrylic or neoprene type primers.

I also think that backer boards are a complete waste of money 90% of the time. They are not water proof, only resistant and can cause problems were none previously existed, due to incorrect usage.

They have their uses and are an excellent product in certain situations, but I will usually fit moisture resistant plaster boards and tank it with mapei gum. Far far cheaper and completely water proof.

Ours was a new build so easy enough to bang up the hardibacker rather than retrofit.

does mapei gum allow the adhesive to get to the board?

No, mapei gum bonds to the board and the adhesive to that. Think of is as a primer. It’s a bit like a sort of blue jelly like glue with grit in it.
Backer board is especially bad for new build as they tend to be timber stud construction. The backer board will absorb water and release it in all directions. Because of the tiles, the easiest path is into the timber. This will then rot behind the board and in the wall.

Backer board is especially bad for new build as they tend to be timber stud construction. The backer board will absorb water and release it in all directions. Because of the tiles, the easiest path is into the timber. This will then rot behind the board and in the wall.

I find that hard to believe given the ubiquity of hardibacker and the manufacturer’s own installation recommendations.

If you’re tiling, the wall doesn’t need to be super smooth, it just needs to be smooth enough that it won’t interfere with the tiles as you site them on/into the adhesive. I took a tile scraper the the wall under neath that made it smooth enough, brushed the dust and then wiped with a damp cloth to get the residue off. Water proof adhesive and then waterproof grout.

3 years in and no problems.

Yup, exactly.

Some of the new wedi boards are very good. They’re non absorbant, comes in lots of different thicknesses. Good for wetrooms especially, floors and walls. It can even be used to construct free standing structures and curves. Very expensive though

I knew it would be a pain in the arse!!!! the room is part plaster board, part brick/breeze block. The wet area is all plasterboard and I think the best action is to replace and tile over…

Thanks for the advice…. I’m wondering if getting a bloke in might not be a bad idea

Wet area, strip it back to brick and dot and dab with moisture resistant plasterboard, tank it with mapei gum or similar and you’re ready to tile. Perfect surface.

Cheers folks….. looks like it’s the plasterboard option

My local builders merchant sells a totally waterproof board for showers. They have a sample that has been in water for years. I would be boarding out with that if its plasterboard walls

My local builders merchant sells a totally waterproof board for showers.

got a brand name TJ? Im betting its “hardibacker” funkyboy 😉

stoner I haven’t got a brand name. I have just seen the sample that is immersed in water without anything happening to it.

I seem to remember them saying its not the usual stuff but that is the limit of my knowledge