NANDIX Repairs · Mason or waterproofing applicator, then painter
Damp patches and seepage on walls
Damp patches, salt marks and peeling paint come from water getting into the wall. Painting over them does not last: find where the water comes from first.
Stop and call a professional: If the damp is near switchboards or wiring, switch off that circuit and call an electrician first.
What usually causes it
- Rain water through cracks in the outer wall, the parapet or the terrace.
- A leaking concealed pipe or a bathroom on the other side of the wall.
- Rising damp: ground water climbing up a wall with no damp-proof course (DPC), seen as a tide mark 1–3 ft above the floor.
- Condensation in closed bathrooms and kitchens without ventilation.
What you can check yourself
- Note when it gets worse: only in rain (outside water), all year (pipe or rising damp), or after baths (bathroom).
- Look at the outer side of the same wall and the terrace above it for cracks.
- Close all taps and watch the water meter or the tank level for an hour: if it drops, a pipe is leaking.
- Feel if the patch is wet at the bottom of the wall only (rising damp) or around a pipe line.
Parts to ask the shop for
- Crack filler or polymer-modified repair mortar for outer-wall cracks
- Waterproofing coating for the terrace or outer wall (ask for a product meant for that surface)
- Alkali-resistant wall primer before repainting
- Anti-fungal wash if there is mould
Take the old part or a photo of it: sizes and threads must match.
What to ask the worker
- Where is the water coming from, and how did you check it?
- Will you fix the source first, or only the inside wall?
- Which waterproofing product, how many coats, and is there a written warranty?
- How long must the wall dry before putty and paint?