A tide-mark stain rising up to about a metre from the floor, with white salty powder
Groundwater is being drawn up through the wall because the damp-proof course has failed or was never installed. The salt band marks the evaporation line.
Read about rising damp →
Patches high on a wall, worse after wind-driven rain, on the south-west elevation
Rain is being driven through porous plaster, failed pointing or a hairline crack. Cape Town's winter north-westers and the summer south-easter make this the most common damp fault on exposed elevations.
Read about penetrating (lateral) damp →
Black spotted mould in corners, behind furniture and around window reveals
Warm moist internal air is condensing on cold surfaces. This is a ventilation and thermal-bridging problem, not a waterproofing failure — sealing the wall makes it worse.
Read about condensation →
Brown-ringed stain on a ceiling that grows during heavy rain
Water is entering above the ceiling. On flat roofs the usual culprits are failed laps, blistered membrane and blocked outlets; on pitched roofs, slipped tiles, failed valleys and cracked mortar at the ridge.
Read about roof or rainwater-goods leak →
Damp on the wall directly below a balcony, planter box or upstairs shower
The membrane under the tiles has cracked or was never installed. Water tracks through the screed and exits at the first horizontal joint below.
Read about failed wet-area or balcony membrane →
Water standing against the house after rain, or a persistently wet section of garden
Ground water has nowhere to go and is loading the foundation and the base of the wall. Common on the Southern Suburbs' high water table and on sloped Helderberg sites.
Read about surface and sub-surface drainage failure →
Damp on an internal basement or retaining wall, with no rain overhead
Soil water is pushing through the structure from the negative side. Coating the inside with ordinary paint will simply blow off.
Read about hydrostatic pressure through a below-ground wall →
Still not sure? That is exactly what the free inspection is for.
Common questions
Is this a substitute for an inspection?
No. It is a way to arrive at an inspection already knowing roughly what the problem is, so you can tell whether the diagnosis you are given makes sense.
What if none of the symptoms match?
Then it is worth an actual look. Several faults present at once more often than people expect — a roof leak and a condensation problem in the same room is common.