Damp Patches On Plaster

[AndyMarsh]

Hi all,

I hope i've put this in the right place.

A while ago I stripped the paper off the back wall in my kitchen and around the back door. The plaster underneath seemed quite crumbly and came away easily so I took quite a bit off the wall and exposed the brickwork. The mortar between the bricks seemed quite crumbly too...it was a bit like soil really.

Anyways, I got a lad in and he boarded the exposed brickwork and skimmed over the top. Everything was okay for a while but then damp patches started to appear and have gradually got worse.

The funny thing is, the patches seem to be in random spots. They haven't started at the bottom of the wall and worked their way up. They just seem to be all over the place.

Before I took the original plaster off I got a guy from a damp proofing company to come round and he said it wasn't rising damp but it could have been water coming in round the door frame.

I've linked to some pics. I hope someone has some idea what might be causing this.

 

[roughcaster]

A classic example of what can go wrong when you dot and dab plasterboard straight onto old brickwork. Always better to render scratch coat the old bricks first (3 to 1 or 4 to 1 sand/cement), with waterproofer in the mix,, then after the scratch coat has set and cured, then you can d/d onto it.
Even then, you'd need to make sure the source of any damp is treated first. Quite often though, damp/salts/efflorescence within the brickwork itself, will travel through the gypsum plasterboard, showing up as "damp" patches, or as a fluffy white powder/chrystals on the surface of the wall. The randomness of the "damp" patches is where each dab is located on the brickwork, prior to the sheets being dabbed on. There is nothing like dry, "unpainted" plaster for showing up any damp patches.

 

[NickB_99]

Hi Andy.
Who did you get to do the job - was it a pro spread or otherwise?
R/c is bang on, as usual.

Looking at at least the first pic, the skim seems not to look that flat - even on boards.

May have to bite the bullet and get it re-done. Or try get same guy back to do as r/c says.

 

[roughcaster]

Hi Andy
Who did you get to do the job - was it a pro spread or otherwise?


Looking at at least the first pic, the skim seems not to look that flat - even on boards.

That really is rough plastering,,, it's like a ploughed park,, shocking,, no other word for it.