Val McGee

[Val McGee]

Can anyone tell me why two plastered brick walls, one rear exterior and one party wall (no problem other side of party wall) newly plastered (3 times) will not dry completely but remain damp in patches at around 2-3ft from the ground. Patches have damp meter readings ranging between 20-50%. Both walls have an injected DPC course.

Last replastered 7 months ago and painted 6 months ago but paint began falling off again 4 months ago. Currently paint is removed again to expose plaster to air.

Bricks behind plaster have been found to be dry, as was plaster immediately in contact with brickwork but plaster becomes increasingly damp towards surface, suggesting moisture in atmosphere though we have no other problems of damp or condensation. A dehumidifier working day and night extracts at best 0.9 litres per 24 hours with no change in damp patches on plaster.

Can anyone help please?
Val McGee

 

[Matthew]

You have done lots of right things and so the problem seems quite strange - I would have guessed lack of ventilation but I don't know if 0.9 litres is low or high. Have you checked all possible sources of water ingress (roof, gutters, plumbing, soil levels)? Can you provide some more information - is this an old house (i.e. lime mortar) or newer? I have experience of sorting dampness in a mid 1800s house - see my blog - google "house in the enchanted forest"+ "matthew" (they won't let me post the link)

Matthew