Case study
Campsie: Concrete Floors and a Bridged Damp Course
The Property
A house in Campsie rebuilt around 1980 on older foundations, with concrete floors throughout, tiled, and cavity brick walls. The owners were planning a renovation and wanted to know what they were dealing with first.
From their photos, before I arrived, I expected severe rising damp caused by the concrete floors bridging the damp course. The concrete floors were confirmed as soon as I walked in.
What I Found
Inside, render and paint had failed from the skirting up to about 600mm, with white powder and render crumbling onto the tiles. Outside, the newer face brick had a plastic damp course that was visible and still working. The only deterioration on the outer skin was below that damp course, where an exposed aggregate path ran hard against the wall.
One external wall had a wet band lined up with a shower on the other side. That was most likely a shower leak, not rising damp, and needs a different fix to injection.
What was causing it
The inner walls had either been bridged by the slab or never had a working damp course. A concrete floor stops the ground under the house drying out, so more water goes up the walls instead. The outer skin was protected by its own damp course, so each leaf of the cavity wall needed its own decision.
What I quoted:
- Injection to the inner leaf of every wall
- Render removal to about 1.2m on average
- Skirting tiles, door jambs and architraves off throughout
- External injection below the plastic damp course at the front, plus salt extraction
- A second option including the two bathrooms and kitchen
The lesson
Concrete floors and rising damp often go together. And in a cavity wall, check each leaf on its own evidence before deciding what to inject. See the best treatment for rising damp.