Hi, [apologies for lengthy intro]
Our house is 45 years old, and cut in to a slope at the front, so the internal floor is about 3 feet below ground level. House construction is pretty unusual (for 1960's) with the ground floor being aircrete block.
We've had a persistent penetrating damp issue in one corner. In the Winter liquid water makes it's way in. Visible droplets.....not a lot but definitely visible. This concerns me as there must presumably be a "head" for liquid to make its way in!
In the past I've been advised to hack back the plaster internally, "tank" the corner and replaster. I've resisted this until I understand the underlying cause of the problem. Today I started to dig an investigative hole.
So far I have found:
- Soil is heavy silty clayish sand. Definitely not free draining.
- Exterior render (underground) is apparently in good shape
- Mysterious clay drain pipes about 1 foot long, and about 1 foot below internal floor level....but they go nowhere! (and I suspect full of silt anyhow)
I have not found any visible settlement cracks underground (which I had been expecting).
Next weekend I will take the trench round the corner and see what I can find there. I sincerely hope to find some cracks to explain the penetrating water.
My plan is as follows (with embedded questions):
- Finish digging the trench. But I'm already 9-12" below internal floor level. Should I go deeper?
- Paint external wall with appropriate bitumenous waterproof product like "Synthaprufe". Is this the best product? Are there better ones?
- Remove the clay pipes and lay corrugated plastic "land drain"along the whole length of the trench, falling downhill from the dodgy corner.
- Backfill trench with shingle to ensure free draining.
- Tank and replaster the internal wall as well (belt and braces!).
Pix here:
Any other suggestions?
David