Damp breaking through DPC

[000dave000]

Hi. I have damp coming in from between my concrete floor and external cavity walls. I've worked out that when the house was built ('50s) they left about a 1" gap between the concrete floor and the brickwork. There's a plastic damp proof membrane which bridges the gap. They've plastered the walls (presumably before laying the floor) down into the gap down to the membrane (see piccie).

Untitled

• 000dave000
• 14 May 2011
• 1

Over the years some of the membrane has failed and it looks like moisture is being sucked up by the plaster causing damp.

I've chipped off a couple of inches of plaster all the way round so that won't happen again, but I'm wondering if that is enough or do I need to do anything else. Where the membrane is broken could moisture make its way up the brickwork?

Any advice appreciated.
Cheers. Dave.

 

[r896neo]

if you sure that is the cause then ideally you need to carefully expose the dpc and dpm edges and coat the whole area in liquid dpm then replaster with waterproofer in your scratch coat for good measure.

However it would be unusual for the base of the concrete floor to be level with the dpc as in your diagram.

What is more likely is that the dpm is folded up the wall and tucked in which may affect how you need to go about it.

 

[^woody^]

The wall would normally have a DPC in addition to the DPM, and this would prevent moisture rising in the wall

Your plaster should not be touching the floor and may be a source of damp if it is

But that is a very odd detail if that is how the DPM and wall/floor is arranged