We recently discovered that ground floor living room of our Victorian terrace house is a concrete slab, under which is a layer of DPM, then sand, then soil. When we opened it up, we were expecting to find a suspended timber floor, with a void providing ventillation (this is what the neighbours in our terrace have), but think this was done around 1980 for some reason. We suspect that this is causing persistent damp in the surrounding walls. We are planning to treat this with 1 metre of sand cement on most of the walls in the living room. The extension we're building at the back is at a lower level (about 3 steps down), and those walls are also affected (we discovered this while digging into the wall to build the steps). Does anyone have experience with this? Is it common practise to fill in a void, and or is it something we should be worried about? We don't have the budget to pull up the entire floor and excavate, but want to minimise problems with damp. Thank you!
Soil-filled subfloor void under Victorian House
- Thread starter LKP1000
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Sounds like you could find yourself with a free cellar!
My parents had cellars wen ah wer a lad, but t'wife and I have never had one.
I'd find a cellar a very useful thing personally, though I don't know about damp.
My parents had cellars wen ah wer a lad, but t'wife and I have never had one.
I'd find a cellar a very useful thing personally, though I don't know about damp.
Under my carpet was thin asbestos tiles, on top of some kind of bitumen. I guess it was bitumen as it made the drill/grinder smoke a LOT when trying to cut into it! But on the outside of the house are lots of air bricks, so I assume it was originally a suspended vented floor and someone chucked loads of unknown stuff in the void to attempt to fix a problem. It seems that kind of thing happens to many of us by the sound of it!
i know this doesn’t help on your problem LKP though, sorry. Possibly injected dpm might work but I’m no expert on damp.
i know this doesn’t help on your problem LKP though, sorry. Possibly injected dpm might work but I’m no expert on damp.
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Pictures please
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Where is the damp?
Its around the length of the long wall of the living room, and then the perpendicular wall (that you can see cut into here). This is is the drop-down (3-4 steps) into the new kitchen extension, so the adjoining kitchen wall will be against this already damp wall - if that makes sense!
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Is it pictured?
When a timber floor is removed, filled in, and replaced with concrete, the reason is often that the original floor rotted due to persistent damp.
Unfortunately, filling it in does not remove the cause of the damp. It just conceals it for a while.
If the cause was, for example, a leaking pipe or a broken drain, covering it with concrete just means that the cost of digging it out and repairing it is even greater.
Look out for any drains or gullies, and the probable route of your incoming water pipe, which may give clues. It often happens in or close to kitchens. The ground near a leak is often sunken where the water has washed soil away, and paving or concrete round a broken drain has often been patched up to hide cracking.
Unfortunately, filling it in does not remove the cause of the damp. It just conceals it for a while.
If the cause was, for example, a leaking pipe or a broken drain, covering it with concrete just means that the cost of digging it out and repairing it is even greater.
Look out for any drains or gullies, and the probable route of your incoming water pipe, which may give clues. It often happens in or close to kitchens. The ground near a leak is often sunken where the water has washed soil away, and paving or concrete round a broken drain has often been patched up to hide cracking.
The one thing you can be sure of, is that silicone injections do not repair leaks, or building defects, or provide drainage, or add ventilation to evaporate away moisture.
Get rid and replace. Or you are just going to have more problems down the line. I know the focus and excitement at the moment is on the new extension, but proceeding without fixing this is getting your car resprayed but ignoring the faulty brakes.
Dig out, put in a solid insulated floor and you'll have a warmer, dryer home.
Like John says, you may have an existing leak somewhere so you can investigate that at the same time. Or it could be the case that the original joists rotted due to blocked airbricks, and the homeowner or their builder had no inclination to tackle the woodwork involved in rebuilding it, and just had a load of soil to get rid of.
They don't call them money pits for nothing!
Dig out, put in a solid insulated floor and you'll have a warmer, dryer home.
Like John says, you may have an existing leak somewhere so you can investigate that at the same time. Or it could be the case that the original joists rotted due to blocked airbricks, and the homeowner or their builder had no inclination to tackle the woodwork involved in rebuilding it, and just had a load of soil to get rid of.
They don't call them money pits for nothing!
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