Hi
I have just bought a 1870's stone cottage in sunny wales. The outside ground level of the house is generally higher than the internal floors. We already have water leaking in through an extension wall. I have been advised to dig a trench around the house about a foot and a half deep and a foot wide. Then to fill with a certain size gravel.
Has anybody done this before? Is there some basic specifications to stick to.
Any help is much appreciated.
gravel drainage trench - outside ground level is higher than internal
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designcurb
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alan ditchfield
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I have never come accross this problem myself but it sounds to me like the outer ground level needs to be lowered and drained properly, the ground level should be 150mm below damp, if you just dig a trench and fill it with gravel you will attract water not deter it. Has the original house had any treatment that the extension has not ?
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84-1093879891
Sunny Wales? Is that anywhere near rainy Wales? ;)
What's been recommended to you is a form of collector drain or French drain. In principle, it's fine and would have been the best soluition back in 1870 when the cottage was new, but we've moved on a bit during the intervening 134 years and there are better solutions now available to you.
The most obvious one would be to use a drainage composite to line the walls. Basically, the external faces of the walls are excavated and exposed to a depth below that of the internal floors. This should be an absolute minimum of 150mm lower than internal floor level, but the deeper the better, really.
The drainage composite I'd recommend would be a one-way sandwich, which is a dual layer product featuring a permeable membrane on one face with an impermeable on t'other, held apart by small 'dimples'. The idea is that water can penetrate the permeable membrane and then fall down the gap between the two membranes and into a collector drain, which then leads it away to somewhere more appropriate. The impermeable mebrane against the wall protects the building from further damp penetration.
The drainage composite can be fitted to a trench only 150-225mm wide, but it's usual to allow the contractor to excavate a trench that will ensure adequate working space, so this may be 400-600mm in width. The composite is put in place and then the trench is backfilled with 'free-draining material', usually a clean, inert gravel.
The collector drain is essential to the functional success of such a construction. There must be somewhere for the water to go - it's no use doing all this work and then letting the water sit there. It must be directed to an outfall of some description, and this may be a stream or ditch durther downstream, a soakaway at least 10m away from the property, or as a last resort, and existing SW system.
I can't give you a definitive spec or step-by-step guide as each job is unique and I haven't seen this project, but I would suggest you get a local drainage contractor or building surveyor to take a look and give you the benefit of their onsite advice.
What's been recommended to you is a form of collector drain or French drain. In principle, it's fine and would have been the best soluition back in 1870 when the cottage was new, but we've moved on a bit during the intervening 134 years and there are better solutions now available to you.
The most obvious one would be to use a drainage composite to line the walls. Basically, the external faces of the walls are excavated and exposed to a depth below that of the internal floors. This should be an absolute minimum of 150mm lower than internal floor level, but the deeper the better, really.
The drainage composite I'd recommend would be a one-way sandwich, which is a dual layer product featuring a permeable membrane on one face with an impermeable on t'other, held apart by small 'dimples'. The idea is that water can penetrate the permeable membrane and then fall down the gap between the two membranes and into a collector drain, which then leads it away to somewhere more appropriate. The impermeable mebrane against the wall protects the building from further damp penetration.
The drainage composite can be fitted to a trench only 150-225mm wide, but it's usual to allow the contractor to excavate a trench that will ensure adequate working space, so this may be 400-600mm in width. The composite is put in place and then the trench is backfilled with 'free-draining material', usually a clean, inert gravel.
The collector drain is essential to the functional success of such a construction. There must be somewhere for the water to go - it's no use doing all this work and then letting the water sit there. It must be directed to an outfall of some description, and this may be a stream or ditch durther downstream, a soakaway at least 10m away from the property, or as a last resort, and existing SW system.
I can't give you a definitive spec or step-by-step guide as each job is unique and I haven't seen this project, but I would suggest you get a local drainage contractor or building surveyor to take a look and give you the benefit of their onsite advice.
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designcurb
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