Damp in concrete floor
How to deal with damp in concrete floor
- In principle all concrete floors should include a damp proof membrane across the whole floor area and this should be linked to the damp proof courses in the surrounding walls to provide continuity of protection against ground moisture.
It follows that any breaks in the membrane will lead to dampness of one degree or another within the floor area. Because the source of failure is often so difficult to pinpoint, you could be looking at having to renew the floor in its entirety.
One alternative that may be feasible is to apply an epoxy resin coating across the floor to seal it against damp. Two coats are usually required with say 6 hours between, so it can be done in a day. But you need to be able to get at the whole floor area up to the surrounding walls so if it's a kitchen, all the units will have to come out. Surface preparation prior to application will be crucial but even so it will be less disruptive than taking up and renewing the floor.
Not a DIY job though.
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
How can I tell if the house has condensation problems or it is rising damp ?