Patches on external wall

Anoneemoose

Hi. We’ve had these patches on our wall in the dining room for years. My first thought of course is damp patches but they don’t seem wet, nor is there any mould anywhere. The patio door is extremely old and leaky at the bottom, could that be causing it somehow? We are having the patio door replaced in a couple of weeks so will see if that makes any difference. 

I know we’ll need to get someone to look at it but I wondered if anyone had any ideas as to what it could be in the meantime. It doesn’t actually affect anything (as far as I know) apart from looking a bit dodgy.

Thank you in advance for any info. 😊

pramsay13

Was it newly plastered when it got painted?
I think it maybe just needed another coat or two. 

Anoneemoose

pramsay13 said:

Was it newly plastered when it got painted?
I think it maybe just needed another coat or two. 

Thank you. It was originally, but it has been a different colour before this, so it will have had a ‘mist coat’ (I think that’s what you call it), two coats of the old colour and then two coats of the blue you see. 

grandadgolfer

Have you checked the outside guttering and drain pipes for leaks/overflowing

Anoneemoose

grandadgolfer said:

Have you checked the outside guttering and drain pipes for leaks/overflowing

Thank you also. I haven’t recently though I don’t think there are any problems. I will definitely check though.

FreeBear

grandadgolfer said: Have you checked the outside guttering and drain pipes for leaks/overflowing

If it were damp from an external leak, I would expect to see a larger single patch - These appear to be regularly spaced patches suggesting dot'n'dab plasterboard. The spots where the adhesive is will be slightly colder than the surrounding plasterboard, As a consequence, any moisture in the air would condense on the cold spots first.

Short term, not much you can do about it. Long term, strip the wall back to bare brick, insulate (perhaps with ~50mm insulated plasterboard), and replaster. Wrap the insulation around the door reveal to limit a cold spot forming in that area.

Anoneemoose

FreeBear said:

grandadgolfer said: Have you checked the outside guttering and drain pipes for leaks/overflowing

If it were damp from an external leak, I would expect to see a larger single patch - These appear to be regularly spaced patches suggesting dot'n'dab plasterboard. The spots where the adhesive is will be slightly colder than the surrounding plasterboard, As a consequence, any moisture in the air would condense on the cold spots first.

Short term, not much you can do about it. Long term, strip the wall back to bare brick, insulate (perhaps with ~50mm insulated plasterboard), and replaster. Wrap the insulation around the door reveal to limit a cold spot forming in that area.

Thank you for replying. That’s really helpful and makes total sense. I’ve heard of dot’n’dab in relation to the plastering by the guy who normally does ours. We are getting the ceiling skimmed at some point soonish in there so I’ll get him to sort it out for me. 

I did wonder if it was something to do with the cold, as opposed to it being wet from something.

Thanks again! Much appreciated.

jonnydeppiwish!

Have you used a decent stain cover paint before painting over it? Something like a Zinsser type should block it if it’s just a stain coming through. Be careful with it though - it’s very watery!

Anoneemoose

jonnydeppiwish! said:

Have you used a decent stain cover paint before painting over it? Something like a Zinsser type should block it if it’s just a stain coming through. Be careful with it though - it’s very watery!

I haven’t tried that. Good thinking though. I’ll weigh it all up before going ahead.

stuart45

How thick is the wall? It looks quite thin in the photo.

Anoneemoose

stuart45 said:

How thick is the wall? It looks quite thin in the photo.

I can’t measure exactly as the current patio door won’t open but from inside to outside the patio door frame is approximately 40 odd cm.