Thu, 30 Apr 2026 06:21:36 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307197#Comment_307197 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307197#Comment_307197 Sun, 10 Nov 2024 22:31:27 +0000 luz13827
I'm at the point where I just want to hire someone to come look and tell me what could be causing the issue, but I don't know what specialist would know this (familiar with old buildings, the material on the outside, etc). Does anyone know of someone recommended in London? We are in a converted ground floor flat, so this room is set to become my baby's room, and before we re-decorate, I really want to solve the issue once and for all. ]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307198#Comment_307198 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307198#Comment_307198 Mon, 11 Nov 2024 06:50:11 +0000 Dominic Cooney I think you silicon a small piece of glass to the suspect area.
If you see moisture on the surface it’s condensation, if it’s under the glass then it’s in the wall.
(Somebody correct me if I’ve got it wrong)
That would give you a starting point.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307199#Comment_307199 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307199#Comment_307199 Mon, 11 Nov 2024 11:14:00 +0000 djh
My first thought was SPAB, and indeed they suggest calling their Technical Advice LIne to find a contractor or surveyor in your area who is suitably qualified/experienced. They also mention the local Conservation Officer if you are in a conservation area.

https://www.spab.org.uk/advice/technical-advice-line]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307201#Comment_307201 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307201#Comment_307201 Mon, 11 Nov 2024 18:30:04 +0000 Victorianeco https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307205#Comment_307205 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307205#Comment_307205 Thu, 14 Nov 2024 17:58:47 +0000 tony
I already suspect hygroscopic surface layer(s) and no damp in the walls but let’s put my theory to the test before spending money on unnecessary work.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307206#Comment_307206 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307206#Comment_307206 Thu, 14 Nov 2024 20:30:53 +0000 djh
Lauren, is the wall bare clay or is there any paint or anything else over the top of the clay?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307207#Comment_307207 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307207#Comment_307207 Fri, 15 Nov 2024 10:18:27 +0000 luz13827
Aside from this wall, we randomly have one other area in the house which has a damp patch on the bottom of the wall. In this case, the wall is an internal wall (but an old solid brick wall that goes down into the ground), so it doesn't make sense for it to be condensation. I *think* fixing the drain may have fixed this issue, but I can't tell 100% unless we drill the holes and assess for moisture content now, after letting it dry out a bit. The house is well ventilated, it is well heated, we don't dry clothes indoors, we have a strong extractor in the kitchen, dMEV etc. I

'll take some photos shortly when baby gives me a minute! I really believe it's something external which is why I would love if someone could come visit and assess the outside for things I may not be aware of.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307209#Comment_307209 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307209#Comment_307209 Fri, 15 Nov 2024 13:31:01 +0000 djh
A couple of other thoughts. Do you have an infrared thermometer? (they're quite cheap if you wanted to buy one) If so, point it at the damp patch and an area nearby and see if there's a noticeable difference in temperature. Or if you have a humidity meter you could try putting that next to the damp patch and at a similar point nearby to see if there's much difference. It could be a little tricky to get consistent readings though, depending on the type of humidity meter.

One good feature of clay is that you can make good repairs if you do drill a hole or two. Clay paint is easy to use for a final finish, BTW.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307210#Comment_307210 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307210#Comment_307210 Sat, 16 Nov 2024 10:08:21 +0000 luz13827
If you look at the photos with the green coloured wall - there's one small patch on the floor (about 2.5/3 inches wide), and one larger area about 2 feet up the wall. They are on opposite sides of the same (external) wall. On the other side of the where the larger patch is, is a drainpipe. Initially, both of these appeared as only a darker (damp?) patch, but now looks like either salt has appeared, or mould has grown. Also looks like some salt or mould in the corner of the wall.

You can sort of see that there is a shelf adjacent to this wall, but there is at least around 6 inches of space (I'm careful not to block external walls, to allow for air circulation). It is a terraced property. To note, there is nothing/no damp patches/mould around the windows, which to me also suggests it's not a simple heating/cold wall issue. We also very very rarely get condensation on the inside of the window. I think last winter I only saw it on a few occasions when it was extremely cold temperatures overnight. We have not seen that at all this season so far.

The last photo, with the lighter colour clay, is of an entirely internal wall, in the middle of the house (but the solid wall goes into the ground). This used to show a visible circular damp patch every time it rained, which makes me think the cracked drain at the front of the house was somehow letting water underground and to reach this area. Since we fixed the drain, it no longer seems to become more prominent when it rains, and it may be drying up & just stained.

We plan to redecorate the room before our baby moves in there, so it's our one chance to get this right (and I really don't want her moving into a room with damp/mould!!!).. I strongly feel like it's something external that's causing this, but don't know what to do to start assessing or remediating. We've had the drain at the front of the property under the ground checked, as mentioned. I don't know if there's someone who can assess the render at the front of the property (it's a painted brick wall, but there's render on the bottom half), to see if that's causing issues.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307211#Comment_307211 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307211#Comment_307211 Sat, 16 Nov 2024 10:08:31 +0000 luz13827 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307212#Comment_307212 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307212#Comment_307212 Sat, 16 Nov 2024 10:08:45 +0000 luz13827 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307213#Comment_307213 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307213#Comment_307213 Sat, 16 Nov 2024 12:49:48 +0000 tony
The masonry has to be damp for this to happen, drainpipe problem?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307214#Comment_307214 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307214#Comment_307214 Sat, 16 Nov 2024 13:43:16 +0000 Victorianeco
•Gutters overflow
•Roof slates aren't directed correctly into a gutter
•Issues with felt
•Cracks in wall further up

You mention brick higher up and render below. Could water be getting in that junction?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307216#Comment_307216 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307216#Comment_307216 Sat, 16 Nov 2024 22:27:38 +0000 luz13827
@Victorianeco, they are all valid questions - but this is why I just want to hire someone to come visit and assess possible defects outside. I am not very knowledgeable on the external side of things - does anyone know of someone who is experienced with this, in London? Our standard builders haven't been much help.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307218#Comment_307218 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307218#Comment_307218 Sun, 17 Nov 2024 09:55:22 +0000 djh https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307221#Comment_307221 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307221#Comment_307221 Sun, 17 Nov 2024 17:48:29 +0000 Jonti https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307229#Comment_307229 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18235&Focus=307229#Comment_307229 Tue, 19 Nov 2024 21:56:12 +0000 luz13827