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Damp Proofing Question
The house we have just bought is part below ground level, and is damp. there is a gully beneath flag stones all around the house, how can we keep the damp out ?
Brick walls - no cavity - built circa 1890.
we have cleaned out all the mud from the gully. Should we reclose the flags and repoint or is there somthing we can do in the gully, line it with somthing or treat / paint somthing on ?
Have to agree with Paul the best solution would be to have the walls tanked that are below ground level which will offer a permanent solution.
Answered 8th Apr 2011
Firstly make sure the flag stones finish at least 3 inches away from contact to the property (they may need cutting back. If possible excavate the gully to below your internal floor level and fill with pea shingle (this acts as a soak away below DPC.
Tanking below ground level will not work unless you then add a dpc installation to top of tanking, the tanking only acts as a barrier to increase the height necessary for DPC , I have been in this trade for 12 yrs and actually know what I,m talking about. firstname.lastname@example.org
In response - I did not say tanking wouldn't hold the damp back
But what I am saying is you have to make sure there is a DPC above the tanking as the held back moisture will rise .
Answered 12th Apr 2011
on the contrary to Dampuk
If you have someone install a tanking system for hydrostatic pressure, it will indeed hold back the water. If you think about a swimming pool holding water in, a hydrostatic compound properly applied and finished is the opposite, it will hold back around 30psi of water pressure (thats per square inch!) without entering even into the first layer of tanking, and properly applied there are several key coats of differing composition before your internal finishing coat. It is also used externally on new sewage process storage tanks to prevent seepage into surrounding ground.
The applications for these compounds are marine concrete protection, however a BBA contractor will know to use this, will use this and it is approved in domestic and commercial use, it's just seen as overkill, but I don't like claims on my insurance so we use this compound and system every time.
These products are not over the counter, nor do the supplyers hand them out to non BBA approved contractors so choose carefully, and you should be in receipt of at least 3 certs upon completion. Insurance, a 30 year plus guarantee, and the BBA registered cert specifying method statement signed by the contractor, and you should also have a product guarantee.
It will in essence not be curing the problem as such, as the moisture will still be there, however it will be held back permenantly and will never eneter into the internal finishes of the room leaving you dry and moisture free!!
Answered 15th May 2011
It sounds like you need tanking applied below ground level, but you could point and spray a waterproofer onto your gully to see if that helps first but I don't think that will be a long term solution.
Answered 6th Apr 2011
Partly below ground level does not tell me the extent of the problem. However, you refer to a gulley all round, presumably this is a drainage channel that has a few drain connections to take the water away. It is not usual for paving to be placed over the channel. Is this paving above the damp proof course in the walls.
Assuming the floor level is some depth below ground then you should clear around the external walls waterproof the brickwork with some bitumen type product, lay in a geo textile membrane and fill with shingle or larger stones. This will help, but if in clay then you might want to introduce a drain to soakaway at the level of the lowest excavation.
Answered 4th May 2012