Here's an idea, go back to the small area shown in your original photos, hack and apply Limelites, finish and allow enough time to stabilise. Cost and time relatively small and it needs doing anyway. If you are still getting surface dampness then crack on and spend as much money as you like taking up floors, installing useless damp proofing, etc. I'll have a little side bet with you that it will be fine.
Damp showing in Chimney breast
- Thread starter icon_boy
- Start date
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No its the sub floorboards.
Makes sense!
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When you dug out the rubble, did it seem damp?
Are you sure the source of water was cured? That rotten joist looks to have been really wet.
The subfloor void is shallower than I had imagined. Is it well-ventilated with lots of airbricks that are not clogged?
The brickwork around the chimneybreast will be packed with rubble that is in contact with the earth, all the way up to hearthstone level, and has no DPM or ventilation, which is why it can encourage damp. This is quite common.
In your picture you can see the brickwork extends forward of the chimneybreast, IME there was commonly a concrete slab or hearthstone or tiles in front of the fireplace to reduce the number of housefires caused when sparks and hot coals fell out of the fire.
It is possible, though unlikely, that tell is right on this occasion and the house was built without a hearthstone.
Are you sure the source of water was cured? That rotten joist looks to have been really wet.
The subfloor void is shallower than I had imagined. Is it well-ventilated with lots of airbricks that are not clogged?
The brickwork around the chimneybreast will be packed with rubble that is in contact with the earth, all the way up to hearthstone level, and has no DPM or ventilation, which is why it can encourage damp. This is quite common.
In your picture you can see the brickwork extends forward of the chimneybreast, IME there was commonly a concrete slab or hearthstone or tiles in front of the fireplace to reduce the number of housefires caused when sparks and hot coals fell out of the fire.
It is possible, though unlikely, that tell is right on this occasion and the house was built without a hearthstone.
The source of the water was coming from the side of the wall, where you can see the rotten part of the joists. This was caused by the groundworks outside being higher than the level of the external wall DPC.
I excavated the ground to around 70cm deep, poured in some concrete to below 30cm of the DPC line, and backfilled with 20mm shingles to below 20cm of the DPC line.
There are times when the water table would be high, and this was penetrating the DPC, The party wall on my neighbours side, also has rising damp; its condition is worse than mine.
When we removed the joists, we had to replace some of the subfloor as it was rotten and wet. The subfloor rubble had been damp too; since the repair, I have been testing with a moisture metre on that side of the wall, and it's within the limits.
There is sufficient ventilation, as I can feel a draft, when I put my hand near the exposed part of the wall, where the side skirting has been removed.
I excavated the ground to around 70cm deep, poured in some concrete to below 30cm of the DPC line, and backfilled with 20mm shingles to below 20cm of the DPC line.
There are times when the water table would be high, and this was penetrating the DPC, The party wall on my neighbours side, also has rising damp; its condition is worse than mine.
When we removed the joists, we had to replace some of the subfloor as it was rotten and wet. The subfloor rubble had been damp too; since the repair, I have been testing with a moisture metre on that side of the wall, and it's within the limits.
There is sufficient ventilation, as I can feel a draft, when I put my hand near the exposed part of the wall, where the side skirting has been removed.
How very dare you ?
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