Hi guys My single storey home which is around 40 years old is built on a concrete slab and has solid rendered concrete block wallswhich are painted inside and out. The perimetre of the slab and the lower few inches of the outside walls is afffected by dampness (damp carpets inside and peeling paint on lower wall. The slab was laid on a plastic damp-proof membrane which wraps the edge of the slab and extends underneath the first mortar course, this membrane seems to be intact. The edge of the slab was fitted with a preformed "L" shaped fibro-cement capping which seems to be there to protect the plastic membrane from damage. I note that the capping extends into the first mortar bed also. I have a theory that the fibro cement capping (which is painted as is the house) may be acting as a wick and feeding moisture from the soil up into the first mortar bed and hence into the slab and the lower brick course, does this make sense to you guys? Thanks, Greg
Posts: 1 | Location: Australia | Registered: 08-23-07
From what you described I think you are correct. The "L" shaped fibro-cement is not letting your base block breath, and with age the fibro-cement is acting like a wick absorbing outside moisture then letting it drip on the inside and landing on the top inside part of the damp-proof membrane. Try cleaning the fibro-cement and digging a 4-6 inch trench around it and treat it with a spray or paint on basement water sealer. Depending on the condition of the fibro-cement you might want to give it several good coats, Then you can paint over it with a paint that matches the house. Check these links out,
