Crackin plaster / paint

Louise Staff asked 4 years ago

We moved into our house nearly 2 years ago. It had a damp problem but the previous owners had a damp proof course put in before we moved in and we were given a 10 year guarantee cert. The walls after the damp proof course had been re-plastered. So on us moving in we primed and painted the walls. The plaster on all the walls was dry except for a bit in the hall wall, just above the skirting board. Not a large bit but we primed and painted it the same as the rest of the walls. But just recently it has started peeling, we scraped the painted back and put more primer on and repainted. But it has just started peeling again and has now bubbled and cracked a bit. Please help, this is doing my head in 🙂 All the other walls seem OK. Thanks

3 Answers
crowderpainting Staff answered 6 years ago

Uncured or not fully cured plaster is to blame. Is there a powdery residue on the surface? Here's some ideas that should help;

* Scrape back the loose paint.
* Wash the surface with some warm water and a small amount of white vinegar. 1 cup per gallon is enough.
* Prime but this time use a PVA primer. PVA stands for poly-vinyl-acetate. Thin 10% and apply 2 coats with 4-8 hours between each coat.

The PVA primer can handle higher than normal ph and should adhere to the plaster giving you a good base for the paint.

Anonymous Staff answered 6 years ago

Thanks very much for answering my query Karl. There is a slight powder residue but on peeling some of the paint back the plaster itself seems to still be wet and coming off the wall. If we scrape all this back and use a PVA primer will that be OK?

crowderpainting Staff answered 6 years ago

Priming won't help as the plaster is still wet. I'm starting to think there is a leak somewhere letting moisture into the wall. Contact the service contractor that did the work and use your guarantee certificate.

One cause of excessively powdery and brittle plaster is being exposed to moisture over an extended period. It is very possible there is still moisture getting into the wall cavity. Only a good evaluation of all possible areas for a leak and repairing these areas will cure the paint problem. Until this is done there is no need to prime and repaint.

Hopefully I'm wrong about a possible leak. If this is the case;

* scrape back all loose paint
* allow the plaster to fully dry (could take a couple of weeks)
* you might need to use some masonry glue to re-stabilize the plaster (check with a local plaster supplier)
* and then do the priming

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