Damp Proofing

Possible rising Damp in Victorian terraced house - advise requested

Darren Mac 02/09/2025 - 2.01 PM

’ve been chasing damp musty smell around my house for weeks but I’m struggling to pinpoint the source of the problem. I’ve lived in the house for 2 years with no issues. The Damp smell started about 2 months ago and gotten worse quickly. I’m unsure if this is penetrating or rising damp. House details: Victorian house built around 1890 which has a rendered concrete plinth of around 2 feet Cavity wall with 9 inch outer brick. The cavity appears blocked but no obvious bridging above ground level Air brick in centre of the front terraced wall No obvious damp on the plaster of the inner wall but there is wetness at floor level in the eves directly below the skirting board Flooring is asphalt or bitumen and this appears damp at the edges. Rising or penetrating? The asphalt flooring appears old and is crumbling around the edges - see images The floor sits on concrete slabs and has a thin layer of sand between the concrete base and the bitumen. The sand layer appears slightly damp around the edges. Unclear if there is a physical damp course on the front wall due to rendered plinth. dry rods have been inserted above the plinth. See images The Inner brick wall has holes in the bricks but no dry rods have been inserted in those holes for some reason Skirting board was attached to the wall with twisted wedges and these were rotting when removed. The ground floor level of brick layer is damp in parts I initially assumed the smell was coming from the rotting skirting boards but smell remains after removing them. A few questions: Could the damp be bridging the cavity at low levels due to the rendered plinth? There is no obvious rising damp on the walls - aside from the ground floor lower brick - which could be wet from the rising damp or from the asphalt flooring?? Could the smell be coming from the old asphalt flooring which might have trapped damp underneath this? BUT, there is no obvious smell coming from the flooring itself or just above ground level. For some reason the smell seems to hang in the air a head height which makes it difficult to locate the exact source of the problem…. Should I consider removing the rendered plinth? Seems like a lot of effort and may not be the cause …I’ve considered adding a box drain at the front but this might not be needed either… Will the old asphalt floor need to be removed or can this just be repaired at the edges? I’d appreciate your thoughts on the mostly likely cause of the damp problem and best remedial solutions to start with…. Thanks, Images here: https://www.reddit.com/r/DIYUK/comments/1mfmzk8/possible_rising_damp_in_victorian_terraced_house/