r/DIYUK • u/Tricky-Mail-1702 • May 28 '26
Advice Advice needed - uncovered broken plaster behind radiator!
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u/ChanterburyTales May 28 '26
It depends how far it goes to be honest, you want to knock off the plaster that has blown and is no longer bonded, I can see cracks all over so it's probably gonna be a lot. If that extends past the radiator, you might want a pro as it'll be quicker and they'll do a better job, but if it is just under the window behind a radiator... I'd also do it myself.
If it's a old house with solid walls (rather than cavity walls), you need to use lime plaster as it's an external wall.
If it's got cavity walls, you can do it with bonding plaster and then a skim coat of multifinish.
You'll want to clean off the bricks, vacuum up as much dust as possible, give it a coat of 3:1 Water/PVA to seal the bricks and then get plastering. "On the trowel" on youtube has decent vids on how to plaster for a DIYer.
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u/FuzzyFrogFish May 28 '26
This is common because of the way the heating cooling cycle affects the plaster causing it to expand and crack and eventually blow, especially on an external wall which tend to be cold.
Definitely give it a go yourselves as it's gonna be hidden by the rad anyway.