Tue, 19 Dec 2023 08:37:24 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300366#Comment_300366 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300366#Comment_300366 Mon, 20 Feb 2023 18:25:36 +0000 luz13827
We did a big renovation last year and have moved back in for around 9 months. On the problematic areas we had prior (mould on external walls), we made a big effort to use lime and/or lime/cork insulating plaster on all external walls. Thankfully, we've experienced no mould this year, and a much cosier living space.

However we have just noticed one internal wall has efflorescence and is reading damp on the cheap Amazon meter we have (around 30%). This is the under stairs storage room so we don't use it often and I'm not sure how long it's been like this. This is a solid brick wall that goes into the ground, however it is in the middle of the property (terrace property) so I don't think it can be water in the ground from rain. We have neighbours on the other side, so I did wonder if it could be something coming from their side, however the worst of it seems to really be internal on our side. None of our external walls have any issues. On our internal walls, we used some sand/cement, some plasterboard. I *think* this wall has sand/cement render on it, over brick. The paint is a breathable Lakeland paint.

There are also no water pipes under this wall. We completely re-did all the pipework/plumbing, with brand new pipes from the street supply, and they don't run under this wall.

We do have underfloor heating within the polished concrete floor, however there are no damp marks on the concrete (and also, I think we'd have boiler pressure issues if there was a leak in the UFH?)

The other side of the wall looks and seems dry, however the other side is waterproof tadelakt, and we had waterproofed the wall (it is a bathroom with just a single bathtub in it, but very seldom used - probably used it four times since we moved back).

Our neighbour had mentioned to us that prior to us buying the property, there had been a leak from a water pipe under that wall. But that would have been 2.5+ years ago... I can't imagine the wall could still be damp from then, and only now just drying?!

Completely at a loss.. we are thinking to hack off the affected part of the wall and assess the brick below, but I really don't know how we can locate the source of the water (it is a polished concrete floor, so we can't just break that apart).

Any ideas?]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300367#Comment_300367 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300367#Comment_300367 Mon, 20 Feb 2023 19:21:39 +0000 kristeva http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300370#Comment_300370 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300370#Comment_300370 Mon, 20 Feb 2023 20:33:35 +0000 luz13827
The concrete floor does have a proper DPM, yes. The original solid brick wall is Victorian so I don’t think that has any DPC (but nor do the external walls, and those are fine).
If it’s the old salts, could that reasonably be attracting enough moisture to get it to 30% damp?

I don’t know the humidity in the air in rest of the property but I think it’s below 60%RH as we have dMEV & decent ventilation.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300371#Comment_300371 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300371#Comment_300371 Mon, 20 Feb 2023 21:23:26 +0000 kristeva
My guess is its the concrete floor if its an internal wall. How annoying after you managed to solve the mould issues.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300383#Comment_300383 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300383#Comment_300383 Tue, 21 Feb 2023 19:02:29 +0000 tony
2) worth having a listen to the wall/floor as a leaking pipe can be audible

3) let the wall dry out for 6 months


I wory about condensation in cupboards, if it is cold in there then moisture will migrate there from places where partial vapour pressure is higher]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300384#Comment_300384 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300384#Comment_300384 Tue, 21 Feb 2023 20:07:00 +0000 djh Posted By: tonyI wory about condensation in cupboards, if it is cold in there then moisture will migrate there from places where partial vapour pressure is higherTrue.Leave a cheap hygrometer in the room, near the damp. If the reading is very high then condensation is a possibility. Most of the hygrometers also read temperature.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300388#Comment_300388 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300388#Comment_300388 Wed, 22 Feb 2023 09:54:11 +0000 luz13827 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300393#Comment_300393 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300393#Comment_300393 Wed, 22 Feb 2023 13:04:01 +0000 djh http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300396#Comment_300396 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300396#Comment_300396 Wed, 22 Feb 2023 15:55:25 +0000 jfb to me efflorescence is more likely to be salts from groundwater than dampness from lack of ventilation (that would more likely show up as mould)]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300401#Comment_300401 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300401#Comment_300401 Wed, 22 Feb 2023 21:33:01 +0000 tony http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300403#Comment_300403 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300403#Comment_300403 Thu, 23 Feb 2023 09:32:17 +0000 kristeva Posted By: jfbhow high does the water table get?
to me efflorescence is more likely to be salts from groundwater than dampness from lack of ventilation (that would more likely show up as mould)

This is what I would have thought, I'm not sure it can be condensation / lack of ventilation.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300407#Comment_300407 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300407#Comment_300407 Thu, 23 Feb 2023 12:28:02 +0000 luz13827
I do wonder if it's from an old leak prior to us moving in, pushing the salts out, and that then attracting moisture. Since around October time, we dumped a lot of stuff in the floor of the room, so perhaps that combined with not enough ventilation then has caused the area to read damp on the meter.

Should have just used lime on this wall too, but really didn't think the internal walls mattered so much as the external!]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300412#Comment_300412 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300412#Comment_300412 Thu, 23 Feb 2023 17:22:17 +0000 Nick Parsons
Back to the beginning. Beware damp meters as an accurate indicator of damp in masonry. Tony has a way of telling what is really going on.

And back to Kristeva's comment re slate dpcs, I think it's a bit of a regional thing. You find very few late Victorian houses with slate DPCs where I live in S.Yorks.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300418#Comment_300418 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300418#Comment_300418 Thu, 23 Feb 2023 22:51:42 +0000 tony http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300419#Comment_300419 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300419#Comment_300419 Thu, 23 Feb 2023 22:58:28 +0000 LF http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300420#Comment_300420 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300420#Comment_300420 Fri, 24 Feb 2023 06:26:11 +0000 Peter_in_Hungary Posted By: LFShellac primer used on a friend's wall having problems 10 years ago. That was an internal wall.
And did it solve the problem - at the time and continuing to today?]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300541#Comment_300541 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17747&Focus=300541#Comment_300541 Wed, 01 Mar 2023 17:16:45 +0000 LF I think we thought it would block the salts leaching out.]]>