My house is stone built, circa 1860, with the back of the house built into a hillside up to the ceiling height of the ground floor. Originally weavers dwellings, houses, the terrace was "renovated" in the 60's to make 15 terraced houses, at which point a brick cavity wall was constructed in the downstairs on the gable and back walls, where the house is under ground. I am experiencing damp along the back and gable walls (to the fireplace), especially in that corner and removed the peeling, salty paper a few months ago, though the wall itself doesnt feel damp to touch, just salty. I intend to address this problem this year (maybe!) and will try and get a look in the cavity space first of all to see if there is any debris which could be causing bridging of moisture from the stone outside wall. If that isn't the issue, I wondered if it's possible that that the black rubbery looking physical damp proof membrane between the bricks in the cavity wall below ground level has decayed and failed? How long would such a dpc last, given that the house was renovated 50 years ago? And if it has failed, how difficult would it be to reinsert a physical dpc? I also have issues with the stone party wall between me and my neighbour, which I don't think has a cavity, but that's a different matter as I think it's penetrating from outside as it's quite high up the wall, but still below ground level if you know what I mean. To complicate matters our house is immediately adjacent to a road that runs along the back of the property, and public steps down the gable end!
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failed damp proof course?
- Thread starter maggie73
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Penners
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Hmmm - it sounds as though you've got a complicated situation there, Maggie. And as with any damp problem, diagnosis from afar is extremely difficult. Hence the rather rambling comments that follow.
If I understand you correctly, the second, brick wall (constructed to create a cavity) is on the inside of the stone wall, and has some sort of damp-proof course in it. Is that right?
"Rubbery-looking" isn't easy to pin down to a specific material, as it could be one of a number of materials. However, given that the wall was constructed in the '60s I suspect it is more likely to be a bitumen felt, rather than the thick polythene that's used nowadays. Or it could be a liquid material called Synthaprufe, which dried into a black, rubbery coating. But the latter was more usually used on floors.
Either way, if the damp salts are evenly distributed right along the wall, then I suspect that a DPC failure is an unlikely (but not impossible) cause. DPC failure usually presents itself as localised patch(es) of damp, unless the DPC fails along its entire length - which would perhaps be unusual.
When the new, inner wall was constructed, do you know whether any measures were taken to drain any damp ingress that might have occurred within the cavity? I think your plan to try and get a look inside the cavity is a good one - you may, as you suggest, find wet debris in there, or even (although less likely) standing water.
The ideal solution would be to take measures to dig back the soil that rests against the exterior of the back wall. But, if I understand your explanation correctly, that land is a public road, so this is clearly impossible.
I suggest you proceed with your plan to try and get a look inside the cavity, then come back and tell us what you find.
If I understand you correctly, the second, brick wall (constructed to create a cavity) is on the inside of the stone wall, and has some sort of damp-proof course in it. Is that right?
"Rubbery-looking" isn't easy to pin down to a specific material, as it could be one of a number of materials. However, given that the wall was constructed in the '60s I suspect it is more likely to be a bitumen felt, rather than the thick polythene that's used nowadays. Or it could be a liquid material called Synthaprufe, which dried into a black, rubbery coating. But the latter was more usually used on floors.
Either way, if the damp salts are evenly distributed right along the wall, then I suspect that a DPC failure is an unlikely (but not impossible) cause. DPC failure usually presents itself as localised patch(es) of damp, unless the DPC fails along its entire length - which would perhaps be unusual.
When the new, inner wall was constructed, do you know whether any measures were taken to drain any damp ingress that might have occurred within the cavity? I think your plan to try and get a look inside the cavity is a good one - you may, as you suggest, find wet debris in there, or even (although less likely) standing water.
The ideal solution would be to take measures to dig back the soil that rests against the exterior of the back wall. But, if I understand your explanation correctly, that land is a public road, so this is clearly impossible.
I suggest you proceed with your plan to try and get a look inside the cavity, then come back and tell us what you find.
Thanks Penners. Yes, the cavity wall is built within the stone wall, and in theory I feel that this should be keeping out the damp, but obviously something has gone wrong. I think there are drains that run along the back of the terrace underneath the road, and my fear is that these are damaged and leaking water, which is then seeping into the house: I don't relish the idea of trying to get the council/scottish water to dig up the road to check their drains! That's really interesting that you say a failed DPC would usually show as localised patches. I'm hoping its debris between the walls, built up over the years, though getting it out may not prove easy! Will keep you posted when we work up the courage to investigate.
worms
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If they think there is good reason to suspect their drains are broken, I believe SW will inspect with a fibre-optic camera.maggie73 said:I don't relish the idea of trying to get the council/scottish water to dig up the road to check their drains!
Penners
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I would emphasise the word "usually", Maggie. There are no absolutes in these things, and to a certain extent this symptom will depend on how long ago the DPC started to fail.maggie73 said:interesting that you say a failed DPC would usually show as localised patches
But the drainage run under the road outside your back wall certainly sounds like a logical suspect.