Can anyone tell me what problem I have here?

[ODB]

Hello all

I think I may have a damp problem in the extension to my kitchen. I am no expert but I reckon there's moisture behind the plaster, but I can't see any obvious problems from the outside.

Can anyone tell me; does this look like an 'obvious' problem to anyone?

Thanks!

 

[handyman77]

There looks like there could be a couple of reasons for this.
Possibly looks likes someone has just plastered over existing limeplaster which may have been damp, when effervescent has formed it pushed out the gypsum. I have also seen this occur where people have plastered walls with filler where theres been damp and filler then blows. Anychance this kitchen work was done just before you bought this place.
Gt yourself a damp metre to check if you have a damp problem.

 

[Possel]

Yes, there's dampness in the wall from somewhere (have you checked everything outside?). The dampness is trying to get out and it obviously cannot go through the ceramic tiles so it's all pushed to a small area and that flaking is the result. You seem to have a mixture of old lime and new gypsum (and is the outside rendered in cement?).

Lime is meant to breathe through both sides of a wall to allow moisture to escape and thus internally moisture gets into the room and escapes through draughts. If you seal the room up without sufficient ventilation then it has nowhere to go. It is the opposite of modern design where you live in a sealed box; basically lime and gypsum do not mix. Google "period property" + "dampness" and see what you get.

 

[ODB]

Yes handyman77 I bought the place about a year ago, but it hasn't got any worse (can see from pics I took when I first viewed house). I'm usually pretty good at picking out things like this but the rest of the house was in such a good state I must've ignored it.

Knocking on the tiled bit it sounds hollow, just wondering whether there's a leak I can trace, so I'm going to drill a small hole to see whether there's anything obvious going on.

Just checked outside and I had a blocked gutter leaking onto the wall roughly on the outside of where the bubbling is. I've just fixed this, so maybe I'll leave it for a couple weeks to dry out a bit before I go bananas and redo the interior wall. You can see the dark bit where water's been leaking onto the wall, under the bracket, is that likely to be cause?

The weird colouring on the wall is just a poor mix of paint jobs.

 

[1john]

Was that a chimney at any point?

 

[ODB]

No, as far as I can see it looks like the old exterior wall - the join where the extension is now.

 

[Possel]

You might need to leave it a bit longer than a couple of weeks to dry out, even if that's lime render. The trouble is, if it's cement render than it might well prevent it drying out at all - cement render cracks and allows water to penetrate, then it keeps the dampness there as it can't get out!

 

[ODB]

How can I tell if it's lime or cement render?

I'm probably going to take off the patchy bits of render on the interior to let it breathe a bit anyway.

 

[ODB]

Right, I've finally gotten around to pulling a bit of the plaster off. Looks like plasterboard underneath, which is a bit soft (dents if I press my knuckle to it firmly (don't know if this is normal)) and also cuts with a blade quite easy (see video). Not got enough experience to know whether this is particularly bad or not. It feels damp if I poke my finger in the little hole.

Should I just pull the loose bits out completely to let it dry?

Really appreciate the help chaps.