Repairing Plaster Before Tiles

[chrisb1357]

Hi all

We had some areas of plaster repaired by the council in the bathroom last year but I never gave the plaster a miss coat of paint etc after it dried and we are tilling the bathroom next month. Do I need to apply a mis coat or some other type of agent before we apply the tiles to these area.s

Chris

 

[White Room]

An acrylic primer or sbr, no pva or a miss coat...

 

[Alan.P]

What tiles are you planning on fixing, no painted areas at all.

 

[Bubblecraft]

As above, no miss coat or PVA. Stick with an SBR

 

[chrisb1357]

Hi

I was looking at just a basic white 198x248mm gloss, bumpy tile with list a mosaic border.

But then again I just started to remove the blown plaster and the half the plaster has decided to fall off the wall.

Well this morning I started to remove the blown plaster. I scored around the area's in the middle but half the other plaster decided to fall off the wall which I guest its a good job I did not try and tile over before hand.
Now where do I go from here. DO i just remove the rest of the top layer of plaster skim for the whole wall as the rest just seems to crumble off and have the whole wall skimmed then maybe tile or paint.

 

[Alan.P]

If the plaster has blown then I wouldn't risk it, take the lot off and either get it re-plastered and skimmed or overboard it with plasterboard, don't skim the plasterboard, just fix straight to it.

 

[BoldreChris]

Yes, looking at the photo, there isn't enough depth behind the pipes to get a layer of plasterboard on top of the existing plaster so you'll have to strip off the crumbly skim coat then repair the holes in the undercoat plaster. When that's dry, PVA the whole wall, let that dry and then skim it all flat. Then when that's dry, prime it with either SBR or a proper tiling primer and when that's dry, you're ready to tile !

Of course, if the undercoat plaster is falling off the blockwork, it'll all have to come off and then plasterboard is your best bet, as above.

 

[chrisb1357]

Hi

Well its all off now. did not take long to be honest as the rest just fell off. The undercoat plaster seems ok apart from them small area's none of that fell off but it does seem a little sandy when touched. Is that normal for undercoat?

Chris

Yes, looking at the photo, there isn't enough depth behind the pipes to get a layer of plasterboard on top of the existing plaster so you'll have to strip off the crumbly skim coat then repair the holes in the undercoat plaster. When that's dry, PVA the whole wall, let that dry and then skim it all flat. Then when that's dry, prime it with either SBR or a proper tiling primer and when that's dry, you're ready to tile !

Of course, if the undercoat plaster is falling off the blockwork, it'll all have to come off and then plasterboard is your best bet, as above.

 

[chrisb1357]

How much would you think to get them holes re plasterd and then a skim over the whole wall?

How come the skim comes off so easy on external or block walls and on the studded walls its fine

Chris

 

[White Room]

Hi

Well its all off now. did not take long to be honest as the rest just fell off. The undercoat plaster seems ok apart from them small area's none of that fell off but it does seem a little sandy when touched. Is that normal for undercoat?

Is it a sand/cement backing coat rather than a gypsum one.