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I mentioned the problem with damp associated with our external walls on a previous post but have since learned more about the issue after a lot of research and investigating.
Am looking for any advice folks here can share. I've come up with an approach that I think is probably the safest but any thoughts on this would be gratefully received.
Here's the overview:
We have damp strongly associated with the lower part of the exterior-facing walls in our property (detached house). There are no tide marks up the walls and rising damp has more or less been ruled out. I have had a series of damp investigators round, in fact. The first few recommended a new (chemical) DPC but I was soon told by others (surveyors who were not trying to sell me the DPC...) that this would be unnecessary. The house was built in 1953 and has a bitumen DPC that the surveyors think is perfectly fine.
The problem, they argued, was far more likely to be debris in the cavity walls bridging the cavity and bringing moisture across to the internal walls from outside. Well, upon investigating via drill / borescope, one surveyor indeed found some debris. A few weeks later, we had some work done on a different section of wall and the builder found another lump of mortar debris about as large as a brick, wedged in at the bottom of the cavity! So this seems to suggest that, yes, we have sporadically deposited debris that could be bridging the cavity here and there.
The tricky issue is that we have polystyrene bead cavity wall insulation, inserted by a previous owner. It is bonded but fragile and so any works to excavate debris will require the insulation to be completely removed.
Having done a lot of reading I'm actually now of the opinion that we should take that insulation out and not reinsert it. (I should say that, as much as I'd like to be able to do this myself, this is definitely one for the professionals!)
This is because our house, which is on a hill (see username...), is in a part of the country rated "severe" for driving rain / wind. Plus - crucially - our cavities are only 50mm wide. I now strongly suspect that the narrow cavity, packed with beads, could be further exacerbating the damp problem along with the debris. There are some good illustrations of this phenomenon here.
We are having the whole house replastered so I want to make sure the damp gets sorted first. And I think leaving the cavities empty while improving insulation in the roofspace and putting in new solid floors with 100mm insulation will be a good way of helping to stabilise the walls.
I can always decide to fill the cavities back in, in the future, if I decide to take that risk.
But what do you guys think?
Am looking for any advice folks here can share. I've come up with an approach that I think is probably the safest but any thoughts on this would be gratefully received.
Here's the overview:
We have damp strongly associated with the lower part of the exterior-facing walls in our property (detached house). There are no tide marks up the walls and rising damp has more or less been ruled out. I have had a series of damp investigators round, in fact. The first few recommended a new (chemical) DPC but I was soon told by others (surveyors who were not trying to sell me the DPC...) that this would be unnecessary. The house was built in 1953 and has a bitumen DPC that the surveyors think is perfectly fine.
The problem, they argued, was far more likely to be debris in the cavity walls bridging the cavity and bringing moisture across to the internal walls from outside. Well, upon investigating via drill / borescope, one surveyor indeed found some debris. A few weeks later, we had some work done on a different section of wall and the builder found another lump of mortar debris about as large as a brick, wedged in at the bottom of the cavity! So this seems to suggest that, yes, we have sporadically deposited debris that could be bridging the cavity here and there.
The tricky issue is that we have polystyrene bead cavity wall insulation, inserted by a previous owner. It is bonded but fragile and so any works to excavate debris will require the insulation to be completely removed.
Having done a lot of reading I'm actually now of the opinion that we should take that insulation out and not reinsert it. (I should say that, as much as I'd like to be able to do this myself, this is definitely one for the professionals!)
This is because our house, which is on a hill (see username...), is in a part of the country rated "severe" for driving rain / wind. Plus - crucially - our cavities are only 50mm wide. I now strongly suspect that the narrow cavity, packed with beads, could be further exacerbating the damp problem along with the debris. There are some good illustrations of this phenomenon here.
We are having the whole house replastered so I want to make sure the damp gets sorted first. And I think leaving the cavities empty while improving insulation in the roofspace and putting in new solid floors with 100mm insulation will be a good way of helping to stabilise the walls.
I can always decide to fill the cavities back in, in the future, if I decide to take that risk.
But what do you guys think?
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