Damp Concrete Floor Affecting Plaster on Chimney Damp can be a major issue in the home. Find answers to questions or post your own here.

[Mark_s_uk]

Hi Forum,

My lounge floor has a serious damp problem which has been diagnosed as the concrete slab. As you see from the photo the damp permeates the immediate area, has affected the plaster on the chimney (plaster in contact with floor) as well as adjacent alcove walls.

Two questions:

1) I have noticed more sweating on the floor on hot days like today (damp clearly glistening) compared to rainy days where it becomes dry. Is there any connection at all with how dry the outside is?

2) a damp specialist said the chimney breast plaster would have been in contact with the floor, and has gone on to recommend a breathable plaster membrane. I'm slightly sceptical because some exposed brick behind the plaster is bone dry.

My view was to fix the concrete slab first (membrane and level) and perhaps re-render the chimney breast; then monitor and take stock...

I do want to get to the root cause of the problem rather than covering the symptoms with specialist products... Hope that makes sense...

Appreciate any feedback and thoughts.

Regards
Mark

[welsh brickie]

cut the plaster away to the brick, at least 30mm from the floor, The skirting will hide the gap, paint the floor with aquapruf bitumen to stop the damp, also paint the back of the skirting with aquapruf

[Mark_s_uk]

Hi WelshBrickie,

Thanks very much for the advice, I'll do some research on Aquapruf and fingers crossed it does the trick...

Kind Regards
Mark