Painted Walls And Prime + Grip - Tile Advice

[Flintstone]

everytime I walk into a room to tile and I see painted walls, I always worry! A lot of the time I've removed any loose with a scraper and scored the rest a bit with Stanley knife, primed with the usual acrylic and tiled with single part flexi and never had an problems.
I've got a job to do next week which some heavy marble tiles and all the walls are painted magnolia, semi gloss, it's a smooth finish and looks to be well on there. Has anyone primed over painted walls with prime + grip to give a good key? I can't remove that paint it's well on there

 

[Tile Shop]

I wouldn't risk leaving the paint on. Seen a few horror stories.

One that I did see done when I was in our showroom, we got a tiler in to convert an old office into a large roomset. White emulsion on a plaster surface. He did a gradual prime coat with BAL APD. diluted (this is very approximate but for old times sake lets just say......) first coat 1:20 and leaving it to soak through the paint, then 1:10, then 1:5. His reason behind it was that this will add an extra bond between the paint and the plaster.

Left it 2 days to dry and tiled it with ceramics..... which was fine cuz they were only around 16kg. not alot could go wrong. But i'd have thought with your mahoosive slabs or rock, no matter how many coats you put on or through the paint, your tiles are effectively only stuck to emulsion.

Its enough to make your bum squeek. Other people may be able to offer a more informed opinion but I'm a little blinkered and can't see past the "tiling onto paint" let alone the "how well is the paint bonded to the surface".

What is the surface under the paint and whats the marble weight per sqm?

 

[Flintstone]

It's plaster onto plaster board I think. I'm not sure on thnot weight of the tiles but there pretty heavy, 650x 350 or there abouts, I have tiled onto painted walls before by just priming them and the tiles have stuck no problem at all.

 

[Tile Shop]

But now, the paint is the least of your worries. Plaster can only hold 20kg max including the addy. You'll need to speak to the marble supplier to find the weight per sqm.

So if the plaster has to come off too, and providing you don't knacker the plasterboard underneath, that will be able to hold 32kg's. But alot of marble these day is also close to that weight (depending on thickness.... sometimes more)

For the hassle that you'll have getting the paint/plaster off and the risk you're putting into the job by going onto a surface that "may" not be suitable, the safest thing to do would be to rip the lot down and replace it with 12mm Hardie.

 

[Flintstone]

I'm not concerned at all about the plaster falling off!

 

[Tile Shop]

oh thats ok then. Then don't prime the paint. I'm sure it'll be fine. Couple of buckets of Wickes own ready mixed (BAL Greenstar if you really wanna push the boat out) and you're good to go.

Oh I nearly forgot. Make sure you stick a blob in the middle too, not just the 4 corners.

 

[Tile Shop]

Nearly forgot another thing.... They need sealing too. Make sure you do that as soon as you've grouted.

 

[Flintstone]

Hilarious

 

[Tile Shop]

I'm not concerned at all about the plaster falling off!

Hang on, this not sarcasm? I'm lost.

 

[One Day]

Don't hang heavy marble onto plastered walls. Just don't.

 

[Flintstone]

Ile have to asses the job on Monday.

 

[peteablard]

Its a no no, don't do it!

 

[Flintstone]

I'm not one for doing something if it's not gonna be safe or have problems down the line. I've used a lot of pretty heavy tiles over the years on all manner of walls and floor, never had any problems, I've not had chance to have a good look at the walls. I know that I have used these same tiles before and had to remove one and it was a real task to get it off, had to cut the plaster board out and re board a small section, there was no chance it was going to fall off.

 

[peteablard]

You don't need to see the job to know you can't tile on paint

 

[Italy]

I'm intruding, I when I do work with heavy materials on plasterboard or on painted walls, fixed wire mesh with cadres 50x50mm, (like the one that put in the substrate sand / cement) to the wall and drown in the glue, now I do not know if the thing is feasible in uk, italy in the plasterboard is fixed to steel rail fixed to the wall, I saw that you put behind plasterboard timber. the flow rate may be different.
If you manage to understand what I wrote ...