Hi all. I have repaired a large flat roof which for the second time was leaking into the back wall of my house and caused damage to the bedroom wall. Having removed all paper I also removed damaged plaster and the Polycel Damp Seal (which I applied after repairing the damage the first time) on the remaining good plaster, which the manufacturers said "they thought" should not be replastered.

I have a plasterer coming this weekend to replaster the wall. He did not mention anything about sealing with diluted pva first to prevent the new plaster drying out too quickly and cracking. Does this need to be done or is there a differerent grade of plaster for this purpose please?

Sorry but as usual I am asking this question at the last moment. Any quick responses appreciated

If the surface is dry and porous, then he needs to PVA and wait until is is tacky. He probably didn't mention it because it is almost impossible to do it without PVA. Its a bit like ordering a sandwich, you can assume it has butter even if it isn't mentioned. Unlike a sandwich, you can't leave it out.

Thanks I realised this eventually. Worrying too much

That would depend on the surface.

The Question relates to a wall which has existing plaster on it. In my experience that is a porous surface.

Thanks all done now.

He removed the plaster....

PVA on a damp treated wall?? You can soak a plastered wall but it will still cause problems even though it's no longer drinking water. It work because PVA also BONDS!

Suction can be controled with WATER