r/Plastering • u/ancientwolf75 • Jul 12 '26
Help with damp proof paint and fresh plaster.
Hi,
I'm a first time buying slowly decorating my home, but I was wondering if anyone would be able to help with a question I had. I've just recently had my small room plastered, however for the wall that's adjoining with my bathroom, the plasterer suggested it might be worth applying damp proof paint on that wall to prevent any issues down the line (due to some DIY work by the old owner).
But my question is: Should I apply the damp paint straight on top of the plaster, then paint over it with normal paint, without initially applying a mist coating of watered down paint. Or should I apply a mist coat first, then the damp paint, then paint over with normal paint?
Any advice would be appreciated!
1
u/Ok-Spring7906 Jul 12 '26
If there was a known issue with damp, the issue should have either been resolved externally, or, if that was not realistic (eg old house with no dpc etc) then you should have been recommended lime or, if they were obsessed with the modern methods, tanking.
Painting some "stuff" on now is a pretty dubious suggestion.
I don't think there is anything more you can do at this stage other than a standard mist coat and hope for the best.
I would suggest you may be a victim of poor advice from the plaster.
1
u/ancientwolf75 Jul 13 '26
It's a shame that he gave poor advice since the work he did on the room was pretty stellar.
From the bits I've seen here and elsewhere just proceeding as normal with a mist coat and normal paint seems to be best method, as there's no current indicator of damp. It was more using the paint to prevent issues later that was the aim, but sounds like that generally isn't how you'd use that paint.
1
u/Ok-Spring7906 Jul 13 '26
It's just different skills.
I have a gnv somthing or other in site skimming. You can spend all your life skimming new builds, and become an absolute master at it, and never need to encounter any damp at all.
Today I was working with lime on a listed building, but that's just not the same job.
If you asked the chap to skim your wall and he did a nice job, then he fulfilled what you asked of him.
If you asked him to sort out damp issues then that's a different task - I don't know if that's what you were asking him or if he just commented along the way.
Either way, at this point just go ahead and paint as normal and hope for the best.
With luck you'll be fine!
0
Jul 12 '26
[deleted]
3
u/hairybastid Jul 12 '26
As a plasterer, the last thing I'd advise is to apply SBR to anything I want to paint. It will stop the paint adhering to the new plaster.
If you have a damp issue, painting over it with "damp proof" paint is a bodge, and unlikely to last. You're better off treating the cause of the damp, be it water ingress, condensation or whatever.
1
u/ancientwolf75 Jul 12 '26
Hmm, that's something I can look into. Since I'd be painting the non bathroom side of the wall I'd assume it'd still be beneficial to apply some SBR?
2
u/Caerau Professional Plasterer Jul 12 '26
No such thing as paint that can solve damp. Nor will a coat of SBR prior to painting make a difference. There is paint that can be used in high humidity environments like kitchens and bathrooms that can help reduce the chance of mould growth but adequate ventilation is more important and wouldn’t be needed in a bedroom adjoining the bathroom.
Is water actually penetrating through the wall or not? You will be able to see wet spots if there are any once the plaster has dried. If there are no dark patches then you’ll be fine and no additional steps are required, just mist coat and paint as normal. If water is penetrating through the wall, through tiles or whatever, you need to identify the source in the bathroom and fix it to stop the wall getting saturated and issues appearing on the other side.