Laying porcelain 600x400 tiles over painted plaster in a bathroom

[AnimalGlu]

Hi,

I'm a first time poster but I have been reading the forum for a number of years and I wondered if anyone has any advice regarding other options that might be available to me when faced with a painted wall.

I have been laying Porcelain 600x400 tiles over Marmox Multiboard on an external wall (red brick - ~1930's) and everything seems to be going well. However, I have a wall that is plastered (looks like multi-finish with a grey base over red brick) and the upper half is painted in what looks like vinyl silk.

I'm happy with the non painted plaster section and this has been primed (twice) with neat BAL Prime APD, as per their recommendations, however my concern is the painted half.

I don't seem to be able to remove the paint using a wallpaper stripper knife without damaging the plaster. I don't have a heat gun to remove the paint and I'm concerned that I'll damage the wall using a steam stripper.

I don't want to overboard, due to the added thickness this will introduce around a window frame so what options do I have?

I have tried a tape test, the paint isn't lifted when I remove the gaffer tape. I have tried applying some tile adhesive and this seems to be sticking well, in fact the paint still isn't removed when I try and lift the dried adhesive.

From everything I have read, I'm concerned about the best method to tile this wall. Is there a mechanical fixing I can use to ensure that my tiles are stuck to more than the paint?

Otherwise I think I will drill a thin 6mm Marmox Multiboard to the painted wall. Is 6mm enough to hold the tile?

Thanks in advance,

 

[On one]

Knock off the old plaster, comb on tile adhesive,tap multi board plumb and mechanicaly secure with screws and washers?

 

[White Room]

Vinyl paint is a mare to remove, multi board but would use dabs of adhesive then mechanically fix through the dabs when there've gone of.

 

[AnimalGlu]

Hi,

Knock off the old plaster...

I was hoping it wouldn't come to that as I'm making more mess than progress but needs must. I assume this is because:-
- There is no point in it being there if i'm mechanically fixing boards
- I can use a thicker board than the 6mm I suggested and not impact the thickness of the wall?
- It will be a flat surface

Thanks,

 

[AnimalGlu]

Hi,

Vinyl paint is a mare to remove, multi board but would use dabs of adhesive then mechanically fix through the dabs when there've gone of.

I assume even though it is hard to remove it will fail eventually with the weight of the tile and the paint lifting.
In addition to the reply I made to wrighty, are there any other options I worry what will be exposed (although I guess it is best to know that now) if I knock off the plaster.

I guess that this is the option that all professional tilers would go for rather than hope that the paint doesn't fail!

Are there any other options that could be less dirty?

Thanks,

 

[Andy Allen]

Use a sander and sand it off. .

 

[On one]

Hi,

I was hoping it wouldn't come to that as I'm making more mess than progress but needs must. I assume this is because:-
- There is no point in it being there if i'm mechanically fixing boards
- I can use a thicker board than the 6mm I suggested and not impact the thickness of the wall?
- It will be a flat surface

Thanks,

Hi AG. I suggested you take off the old plaster as you said you could encounter problems with the window. Knocking the plaster might give you the extra few mm that you need and you mentioned that you didn't want to steam the paint off(although this can be done if you do not leave the steamer in one place for too long)
Also taking the plaster off back to the brick will give peace mind when hanging such heavy large format porcelain tiles(You haven't said how many m2 and what age and condition the plaster is in)
You can use a thicker than 6mm board it probably wont be any dearer.

 

[AnimalGlu]

Hi AG. I suggested you take off the old plaster as you said you could encounter problems with the window. Knocking the plaster might give you the extra few mm that you need and you mentioned that you didn't want to steam the paint off(although this can be done if you do not leave the steamer in one place for too long)
Also taking the plaster off back to the brick will give peace mind when hanging such heavy large format porcelain tiles(You haven't said how many m2 and what age and condition the plaster is in)
You can use a thicker than 6mm board it probably wont be any dearer.

If I buy/rent a steamer, I was worried that I'd need to wait to for the plaster to dry before starting to tile. I assume that is right?

I have 4m2 on one wall and 3.5m2 on another wall with the window.