This is my first post (probably of many). We are in the process of buying a listed building that has been standing empty without any ventilation or heating for the last year. We are aware of evidence of some damp (as well as other problems) so we had a company in to provide an estimate for this & woodworm treatment. The estimate for the later seemed reasonable but I wasn't so impressed with their estimate for the damp. I spoke to the chap on the phone and he said that there were a couple of areas that had a problem and would need attention. Elsewhere they observed levels of damp that were commensurate with a building of this type (200 year old brick & stone). They suggested that depending on the scale of our refurbishment we should have the whole of the ground floor tanked at a cost of ~£10k. I appreciate that this is a significant undertaking and one that we would consider if we thought it were the right things to do. However, my thoughts are that we should really ascertain the point at which the moisture is getting into the house (potentially from above or cracks in the render / repointing etc). Surely tanking is just going to hide the symptoms and not fix the route cause?
Any advice would be appreciated.
If the existing floor does not have a damp proof membrane fitted it would be wise to incorporate one as the floor itself and any future floor coverings will be susceptible to damp.
Given the age and construction type of the property it is inevitable that an element of moisture will be inherent in the building fabric. This is natural and should not pose too much of a problem if equilibrium is maintained i.e as and when the building gets wet - it is subsequently able to dry out.
You can help the process by ensuring that all rooms are aired regularly, the house has plenty of ventilation and is regularly and evenly heated i.e even rooms you do not use regularly as these are the prime culprits for damp.
The above assumes that all other building elements are in good order, roof, windows, rainwater goods, plumbing and that there is no obvious deterioration to the external building fabric allowing moisture penetration.
The folk that provided the quote subsequently emailed to say:
The damp is rising from the ground. You could consider installing a chemical injection damp course which would prevent the damp from rising up the walls, However this would not be 100% effective in the stone walls. Also the party walls could not be guaranteed as you cannot carry out any works in the neighbouring propertys and therefore the dpc could be bridged and prove ineffective. If the stonework is good then chemical injection would workout a lot cheaper and quicker.
Hi, in response to their email - has anyone established whether a damp proof membrane exists within the existing floor?
This needs to be established before any quotes or remediation works can be considered.
You should also remember that a chemically injected damp proof course is not the panacea (cure all) that many companies would have you believe.
It is only as good as prevailing conditions will allow and the operative applying it.
Damp remediation in historic buildings is a contentious issue and yes it would be bridged by the party wall.
I would also offer caution on accepting advice offered by any companies recommending the use of products they sell.
Injected damp proof courses are of limited effect and if independent studies are to be believed are only effective in a small percentage of cases but please take independent advice on this.
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