Hi, I've had a bit of a shock discovery this afternoon and found some issues that I am desperately in need of advice for. Essentially we have begun stripping off plaster so we can get someone to install insulation to our solid walls in contact with the outside and discovered something different entirely. We decided to insulate cold parts of the room due to moisture being attracted to one area in a corner where the solid wall meets the party wall (which we thought was plasterboard due to the hollow sound) and have heard you can get issues if cold air is cooling a cavity at a corner (see damp patch picture). We have discovered that the party wall is lath and plaster and peering through the gap there appears to be the same for our neighbours - we are shocked to find no brick separating our properties at this boundary (upstairs rear bedroom). Also their side is a bathroom and is visibly wet (we can see their bath!) which is not helping our problem as the moisture may be bridging across. Does anyone have any experience of this and what options are available - can it be simply bricked up or are there structural implications i.e is it a supporting wall? Many thanks in advance Dan
Hi Dan. That third pic showing the damp patch is the only real worry - you need to find out where that dampness is coming from. I take it that 'solid' wall is an external wall? What's it like on the outside - ok pointing etc? No overflowing gutters? That damp does, to me, look like it's come through from behind, and is not condensation for example. So it needs investigating and sorting first. If it's from the neighbouring property, they need to be informed 'cos it'll cause issues for them too. If, in the unlikely event they are unhelpful, then you 'put them on notice' in writing that you have discovered an issue that is coming from their house and which threatens to cause damage to yours. If they don't sort it within a reasonable time (consider what would be a reasonable time) then you will call in contractors to do the work and sue them for the whole cost. (And if you do this by the book, you will win.) After any damp issue is sorted, for the party wall I would personally rip it all off (the lathe & plaster) leaving bare studs. I'd then spray all that timber with a wood preserver such as Everbuild Lumberjack - great stuff - and then simply over-board using - ooh - 65mm thick insulated plasterboard. Jobbie jobbed. As for the external walls, after you determine whether there's an 'issue' with water penetration, then also line that wall with insulated p'board - the thickest you can get away with, but knowing that even the thinnest is GREAT stuff
Hi there, many thanks for your post - very helpful indeed. We'll definitely explore more the cause of the damp. It gets worse when colder, doesn't get bigger just darker. It is probably 1 - 2 metres below the roofline and the outside is rendered with a cement render which is a problem in itself. Gutters and render appear to be in tact as far as I can tell. I like the idea of overboarding as this sounds cheaper than other work. We weren't going to insulate this wall as it is not as cold as the others but might not be a bad idea. What about trying to claim back some of the size of the room as the gap between the two lath and plaster walls is around 10cm. I guess the neighbouring damp wall will have to be rectified first. Cheers again and appreciate any more info
I can't believe you only have a lath and plaster wall between you and the neighbours. Surely there's some fire/ building regulation about that?
I know... we are very concerned about it can can only think it was done some time ago. Both properties are victorian and guess the regs were less stringent or someone ignored them completely.
What sort of problem? Anyhoo, I would agree that insulating the boundary wall shouldn't be as much of an issue, so as long as sound isn't a problem, you could reduce the insulation thickness on that wall if you wish. As for reclaiming some of that void, don't forget that half of it is your neighb's - or at least it can be considered a 'party' wall. In any case, if you think that removing all that studwork - and rebuilding it new a couple of inches inwards - is worth it, go ahead. Anyhoo, you need to trace that damp patch source.
Could be a structural stud wall...usually some type of 'A frame' construction. All will be revealed when you strip it off. Brick wall aside, insulation and 2 or 3 layers of PB will help isolate you from the neighbours...after leak is sorted
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