Old damp proofing not working
There is evidence that my property was damp proofed sometime in the past because you can see injection holes. But I still have areas of dampness inside at the foot of the walls. Can you explain this ?
- There could be a number of reasons for continuing dampness - failure of the injected dpc, continuing bridging of the dpc eg because a plinth render has not been removed or part of the wall inside being below ground level and requiring the application of a waterproofing slurry coating. However the most common fault is in the replastering either because a lightweight plaster has been used instead of a sand and cement render with salt retardant additive or secondly where the new plaster has not been stopped short of the floor and so is bridging the new dpc
How can I tell if the house has condensation problems or it is rising damp ?
I had large patches of damp appear after having some standard plastering done. I then had a damp survey done by a specialist surveyor and was told the DPC was bridged due to the plastered walls on 3 sides of room meeting directly with the flooring. I was advised to remove the plaster up to approx 2 ft, re-plaster with porous plaster, leave a gap between the new plaster and the flooring and fill with anti damp solution (some kind of spray was used). 3 months later I now have a tide mark under the back window sill (external wall) approx 1 & half feet up from the skirting boards. There are also slight markings around the other walls. Can you explain what has happened?
I have a brick built miners cottage which is approx 100 years old and is rendered on the front elevation. There is a 100mm spacing between the bottom edge of the rendering and the pavement outside.
The inside walls have what appears to be a 1 metre high cement mixture rather than plaster and at the base about 500mm apart are small round vents about 30mm in diametre which have tubes behind them going into the wall. I have a Royal Doulton Damp Proof Certificate from approx 35 years ago and assume that the vents are to do with this. However I am about to refurbish the rooms and wondered if there was a way to remove them for something more modern as they prevent wallpapering or if after all this time I needed to conduct any type of maintenance on them to maintain damp proofing. There does appear to be salt marks (white powder) on the walls, which I have scraped off, they walls are quite uneven so I would like to plaster and repaint but would not want this staining to come back through