Tiling directly onto plaster

[Participant]

Hi all

I'm doing our downstairs toilet and have begun ripping out today.

The old tiles were directly onto plaster and I'm wondering if I'm pushing my luck tiling directly onto this surface?





The issue I have is we're only half tiling (wife's wishes) so I can't board over it as it'll stick out too far beyond the painted surface in the top half of the room.

If I board the whole thing I'll have to plaster the top half.

So I want to just tile onto that plaster and build out with adhesive where necessary.

P.S. yes the suite and boxing is coming out too!

 

[Maccapacca]

Just set about using a bucket of adhesive smoothing it out first to create a good base.

I’d rather do that than patch the plaster with plaster that might become loose

 

[Hunterlit]

If the old plaster feels sound go ahead. What sort of tiles will they be?

 

[alexakasloth]

As long as it isn't loose then tile directly on top and use a bit more adhesive where needed to level out.

 

[Participant]

Cheers guys, answers I was hoping for tbh. Half expected a barrage of don't even think about its.

I've gone for a standard setting Mapei so should have a little more time to work with before it goes off.

 

[dlockers]

Honestly I've done tiling jobs like this before and I'd definitely second guess now I'm older and dumber. Get it level first otherwise every tile will be torture.

 

[bigfoot4616]

i wouldn't but then i would be getting paid for doing it. i would knock of the plaster back to block in the area to be tiled and then build it back out by sticking on tile backer boards or sand/cement render if not enough depth for boards. if the tiles are heavy like porcilan or stone they will be to heavy for that anyway even if it was flat and solid.

if ceramic's i might possibly be talked into trying to remove all the old adhesive and fininsh plaster, reskim and tile at the customers risk in case of any future problems(assuming thats a gypsum based undercoat)

if you do go over the top of that make sure you prime it with a proper primer, not just pva.(whatever way you go use a proper primer)

 

[Sin_Chase]

You might get away with it if it's not a wet area but your main limiting factor will be weight. Is the plasterboard bonded to masonry, studs etc? All of this can affect the weight bearing limits.

Can you not knock out the plaster and put a thin backing board up and then trim out the top where it meets the paintwork?

 

[Participant]

If the old plaster feels sound go ahead. What sort of tiles will they be?

Quite large porcelain in all probability. 600mm+.

i wouldn't but then i would be getting paid for doing it. i would knock of the plaster back to block in the area to be tiled and then build it back out by sticking on tile backer boards or sand/cement render if not enough depth for boards. if the tiles are heavy like porcilan or stone they will be to heavy for that anyway even if it was flat and solid.

if ceramic's i might possibly be talked into trying to remove all the old adhesive and fininsh plaster, reskim and tile at the customers risk in case of any future problems(assuming thats a gypsum based undercoat)

if you do go over the top of that make sure you prime it with a proper primer, not just pva.(whatever way you go use a proper primer)

Ok thanks. I'm coming to the conclusion that it might actually be less faff (and better) to chisel off the plaster and board it.

You might get away with it if it's not a wet area but your main limiting factor will be weight. Is the plasterboard bonded to masonry, studs etc? All of this can affect the weight bearing limits.

Can you not knock out the plaster and put a thin backing board up and then trim out the top where it meets the paintwork?

I think this is what I'll do. It'll be mega dusty but I'll end up with a very flat and tile-friendly surface.

Anyway today I ripped out some more boxing. There were huge nails into the concrete floor that were a pain to remove. All good fun!



The hardest part I can see so far is how to chase the towel heater pipes into the wall.

 

[aVdub]

Quite large porcelain in all probability. 600mm+.



Ok thanks. I'm coming to the conclusion that it might actually be less faff (and better) to chisel off the plaster and board it.



I think this is what I'll do. It'll be mega dusty but I'll end up with a very flat and tile-friendly surface.

Anyway today I ripped out some more boxing. There were huge nails into the concrete floor that were a pain to remove. All good fun!



The hardest part I can see so far is how to chase the towel heater pipes into the wall.

Box the pipes in, which will create one of those little shelves for sprays and the next toilet roll.

I would take the adhesive right back and trying to start on a good level surface, or you could face gaps running out as you complete a run.

 

[Participant]

Box the pipes in, which will create one of those little shelves for sprays and the next toilet roll.

I would take the adhesive right back and trying to start on a good level surface, or you could face gaps running out as you complete a run.

Yeah I'm putting in a wall-hung vanity unit and toilet, so there'll be a pre wall and a shelf (maybe a niche, I'm negotiating that) hiding the pipes.

I wanted to have a fully tiled stud wall floor to ceiling with a niche (with mini led uplights), but have been overruled...so far!

 

[dlockers]

Pipes are a floor up job and then a plumber job

 

[Participant]

Pipes are a floor up job and then a plumber job

The floor is coming up anyway and I have a grinder.

I was planning to go into the wall to bury the pipes, but in the floor might actually be easier now you mention it.

 

[dlockers]

The floor is coming up anyway and I have a grinder.

I was planning to go into the wall to bury the pipes, but in the floor might actually be easier now you mention it.

Make sure you sheath the pipe work sunk into the wall as mortar eats copper

 

[Participant]

Make sure you sheath the pipe work sunk into the wall as mortar eats copper

I'll do it in Hep2O.

 

[200sols]

Quite large porcelain in all probability. 600mm+.

You need to find out the weight, plaster is the worst surface to tile on.

Plaster = 20kg/m2
Plasterboard = 32kg/m2

These are the maximum weights you can safely tile onto those surfaces, anything higher and you need backer boards eg Marmox.

These weights are the tile + adhesive weight as well. 600mm porcelain is usually over these limits.

Definitely use a tile level system with this size tile, I use perfect level master.

Spoiler: Pic

The hardest part I can see so far is how to chase the towel heater pipes into the wall.

That is easy, just chisel out a channel.

 

[Participant]

You need to find out the weight, plaster is the worst surface to tile on.

Plaster = 20kg/m2
Plasterboard = 32kg/m2

These are the maximum weights you can safely tile onto those surfaces, anything higher and you need backer boards eg Marmox.

These weights are the tile + adhesive weight as well. 600mm porcelain is usually over these limits.

Definitely use a tile level system with this size tile, I use perfect level master.

Spoiler: Pic

That is easy, just chisel out a channel.

Thanks.

I'm using Wickes STS tile backer board for this. They were £9 each so I got them as easy to cut and manoeuvre, being XPS.

I have a tile levelling system, Screwfix no nonsense one, looks the same as your pic so hopefully ok.

With the pipes in the wall it's not so much how to chase the channel, but the pipe work to get it there neatly. I'll have a think.

 

[aVdub]

Thanks.

I'm using Wickes STS tile backer board for this. They were £9 each so I got them as easy to cut and manoeuvre, being XPS.

I have a tile levelling system, Screwfix no nonsense one, looks the same as your pic so hopefully ok.

With the pipes in the wall it's not so much how to chase the channel, but the pipe work to get it there neatly. I'll have a think.

You could channel out behind the rad for the pipes to run into the wall and plasterboard and tile over.

I was lucky to be able to make a wetroom from scratch and ran all pipes this way.

 

[200sols]

Thanks.

I'm using Wickes STS tile backer board for this. They were £9 each so I got them as easy to cut and manoeuvre, being XPS.

I have a tile levelling system, Screwfix no nonsense one, looks the same as your pic so hopefully ok.

With the pipes in the wall it's not so much how to chase the channel, but the pipe work to get it there neatly. I'll have a think.

You can get 90 degree bends which go directly into a valve with a push fit end facing the wall that make this so easy. https://www.screwfix.com/p/drayton-compression-equal-90-trv-adaptor-elbow-15mm/6165r

 

[Hunterlit]

Quite large porcelain in all probability. 600mm+.



Ok thanks. I'm coming to the conclusion that it might actually be less faff (and better) to chisel off the plaster and board it.



I think this is what I'll do. It'll be mega dusty but I'll end up with a very flat and tile-friendly surface.

Anyway today I ripped out some more boxing. There were huge nails into the concrete floor that were a pain to remove. All good fun!



The hardest part I can see so far is how to chase the towel heater pipes into the wall.

Due to the weight of the tiles, that may be the best option. You may as well use Hardiebacker board and do it properly rather than buying plasterboard.