Fix the cause, not the symptom
Damp-proof paint helps as part of a solution, but painting over active damp just traps moisture — the problem comes back, often worse. You have to identify and fix the source first.
The three types of damp
- Rising damp. Moisture wicks up from the ground through the wall, usually with a tide mark up to ~1 m. Needs a damp-proof course or chemical injection.
- Penetrating damp. Water enters through cracks, failed waterproofing, leaking gutters or faulty flashing. Fix the leak, then re-plaster and seal.
- Condensation. Warm, moist indoor air condensing on cold walls — common in bathrooms and poorly ventilated rooms. Improve ventilation and insulation.
What damp-proofing costs
Damp-proofing runs about R120–R280/m² depending on the method and how much plaster needs removing and replacing. A proper job involves removing damaged plaster, treating the wall, re-plastering with a waterproof additive, and only then painting with a breathable or damp-resistant system.
Get it diagnosed
A good painter or damp specialist will diagnose the cause before quoting — be wary of anyone who offers to "just paint over it". Get free quotes from vetted specialists in your area.