Advice on surface preparation please

[Johneeeboy]

Hi Guys

Is there any prep needed to painted plasterboard before tiling onto it, and do you need to prep bare plasterboard with anything before tiling onto it.?

For a floor that has been sheeted over with a thin ply is there any sealer needed before tiling?

Thanks

John

[DEN]

You should use an acrylic primer such as (BAL apd) for bare plasterboard and ply aswell.

[Sir Ramic]

I never prime Plasterboard as the adhesive i use does not specify this. Check with the adhesive you are using but i would be surprised if they said to prime. It wont do any harm though as long as its primer and not PVA.
When you say thin plywood , what thicknes ply are you talking about?

[brian c]

Originally Posted by Johneeeboy

Hi Guys

Is there any prep needed to painted plasterboard before tiling onto it, and do you need to prep bare plasterboard with anything before tiling onto it.?

For a floor that has been sheeted over with a thin ply is there any sealer needed before tiling?

Thanks

John

remove as much of the paint as possible by sanding it down and score walls,then prime.

I also prime plasterboard as this reduces the risk of the moisture being taken out of the adhesive too quickly.

make sure the ply is 12mm and screwed down at 300mm intervals and yes prime it out using an acrylic primer.

All the best m8.

[Johneeeboy]

Originally Posted by Sir Ramic

I never prime Plasterboard as the adhesive i use does not specify this. Check with the adhesive you are using but i would be surprised if they said to prime. It wont do any harm though as long as its primer and not PVA.
When you say thin plywood , what thicknes ply are you talking about?

6mm ply?

[Sir Ramic]

Originally Posted by Johneeeboy

6mm ply?

No way !!! Get rid off it and either use backer boards or minimum 15mm ply.

[eamonn]

[quote=Johneeeboy;69283]Hi Guys

Is there any prep needed to painted plasterboard before tiling onto it, and do you need to prep bare plasterboard with anything before tiling onto it.?

For a floor that has been sheeted over with a thin ply is there any sealer needed before tiling?

Thanks

definalely get rid of as much of the paint as possible it could come away from the wall at any time,

if the adhesive recommends a certin primer use that 1 that way your covered if something does go wrong, if it doesnt i usually use the botament d10 for plasterboard and think its the botament d15 for wood (check), really good stuff.

[macten]

6mm is too thin mate. Should be 15-18mm, the lowest I would go down to in the real world would be 9mm with a 2 part rubber and latex mix. Like others have said - original substrate needs to be fixed solid and so to does the ply. Best to screw at 250mm centers then you will hit the joists.

[Johneeeboy]

Originally Posted by Sir Ramic

No way !!! Get rid off it and either use backer boards or minimum 15mm ply.

I havent put anything down yet, so no worries.Why wouldnt you use thinner than 15mm?

[Sir Ramic]

I dont like ply really but if i had a choice it would be 18mm. People have different theories, i prefer backer boards as long as the sub floor is strong enough. Backer boards dont add strength or very little.
If you have the depth for 18mm or 15mm ply then its ok.
You could use 9mm and Ditra matting too.
What sort of tiles are you fixing and what condition is the floor now..Chipboard, T&G floorboards etc ?

[DEN]

I would use 18mm ply for the floor to give it real stability.6mm is way too thin a substrate for a floor.

[Johneeeboy]

The existing floor is 18mm chipboard t&g with 25mm gyproc planking underneath that with joists at 350mm centres
The tiles I have are 60x30 porcelain