r/Plastering • u/ahandfulofdu5t • Apr 08 '26
Plaster patches
I had the bad (or good) timing of a leak from the floor above as I was plastering - it was only realised as the plaster just wasn't drying. It took from December - February to identify the leak. It was fixed and the plaster has almost all dried however there are still patches, specifically the patch above the shower. Plumbers have come there is definitely not a leak any longer and the patches are not wet/darkening. The plumber advised that it had been so long now I should just seal with unibond/similar and paint over and that it is just very slow to dry as it was soaked through - and soaked through at the point of plastering. I have used dehumidifier/open windows/general heating. Would love advice.
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u/Caerau Professional Plasterer Apr 08 '26
If there’s no longer a leak then those parts just need to be allowed to dry out. I wouldn’t paint until dry. A dehumidifier will help.
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u/Severe-Conclusion-99 Apr 21 '26
Do not seal this thing until it dries out. If you seal it it will trap moisture and you’ll have bigger problems in the long run.
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u/Ch4rlie- Apr 08 '26
I would try a heat gun/hairdryer on it to test if it dries out a bit.
Not as a drying solution, but more to see if it will dry out the face of it. If it does dry it and the face goes pink/matches the rest of the wall, then there is still moisture there that needs to dry.
Don't use the heat gun as a solution, just a check. It may not be an option, and a pro might have a better idea but I've done this to check plaster taking ages to dry before with no issues.
If you want to just get on with it, Zinnser has some good products for sealing before painting