Damp Proofing

DPC completely perished/absent under SLC section of floor

Anonymous user 03/03/2024 - 3.45 PM

Hello, I've a 1970s ex council house which had some minor damp (rising no more than 1-2 feet) up a corner next to patio doors. Also felt like some bulging of the laminate flooring laid over concrete subfloor so lifted flooring to find several patches of SLC were causing the bulges (swear they feel like they're changing no no evidence of cracking so must be wrong) but by the mouldy corner the concrete was like wet biscuit and the SLC clearly damp. Outer and inner skin of the house have bitumen DPC, bricks and mortar below very very crumbly. Found the cavity wall adjacent to the damp was totally blocked and DPC bridged by internal debris, had hoped this would be the cause but simply brushed away the crumbling concrete internally at the floor/wall junction to find a DPM which was not attached to the DPC (in some places looked it had been ripped, in others it was fitted into wet mortar around 1cm beneath the DPC). Where the floor begins to traverse the doorway opening there is no DPC at all, and the DPM simply pops up into the SLC, with the material under the SLC feeling like crumbled mortar. I'm guessing I need to expose the DPM and DPC all around the room (open plan downstairs living room and kitchen so will be a pain), clean out and apply liquid DPM to bridge the two before fitting concrete (as well as hacking off damaged plaster etc). The SLC has white powder on it, assumed carried salts from evaporation - does this mean I should remove all of this material too? Many thanks, T