Mould & Damp Inspection

Almost all mould in South African homes traces back to one of three mechanisms, and they call for completely different repairs. Getting this wrong is the single most expensive mistake homeowners make.

Rising damp is groundwater drawn up through masonry where there is no damp-proof course, or where the DPC has been bridged by a later addition — a raised flowerbed, a new patio, a screeded stoep, or plaster carried down over it. It shows as a tide mark, typically up to about a metre above floor level, often with salt crystals (efflorescence) at the top edge and paint lifting. It is the least common of the three and the most over-diagnosed.

Penetrating damp comes in horizontally through the building envelope: failed roof or balcony waterproofing, cracked parapet walls, blocked or leaking gutters and downpipes, perished window sealant, or driven rain on an exposed elevation. It produces localised patches that darken during and after rain and dry out between, and it is usually the type in play when damp appears mid-wall or high up rather than at skirting level.

Condensation damp is generated inside the house. Warm, moist air from cooking, bathing and drying laundry indoors meets a cold surface — an outside wall, a window reveal, a corner behind a wardrobe, a thermal bridge at a lintel — and deposits water. It is by far the most common cause of visible black mould in South African homes and by far the most misdiagnosed, because it is the only one of the three where the building is not leaking at all. It typically shows in the coldest corners, behind furniture and around windows, and it worsens in winter.

The pattern of the moisture is the diagnosis. An inspector takes moisture readings at floor, mid-wall and ceiling height across affected and unaffected walls. Rising damp reads high at the base and falls with height. Penetrating damp reads high in a patch that does not relate to floor level. Condensation reads high at the surface but the wall behind is comparatively dry.

Relative humidity and surface temperature readings establish the dew point. If the internal humidity is high and the wall surface sits below the dew point, condensation is occurring whether or not the building is leaking — and no amount of DPC injection will change that.

Thermal imaging is useful, but it is widely misrepresented. A thermal camera does not see moisture. It sees temperature difference, which is often caused by evaporating moisture or by a thermal bridge, and an inspector who reports thermal images without corroborating moisture readings is guessing with an expensive camera.

South Africa has no statutory indoor mould exposure limit, and no regulatory threshold that a spore count can be measured against. That matters, because it means a laboratory air-sample result cannot tell you whether your home is legally safe or unsafe — there is no published number to compare it to.

Sampling is genuinely useful in a narrow set of cases: an occupant with diagnosed mould-related illness whose doctor wants species identification, a dispute between a tenant and a landlord or between an owner and a body corporate where evidence will be tested, or suspected hidden growth in a cavity or ceiling void that cannot be inspected visually.

For a typical homeowner who can see mould on the wall, sampling adds cost without changing the remedy. You already know there is mould; what you need to know is where the water is coming from. Be cautious of any provider whose first recommendation is a lab test.

The mould commonly called "black mould" is usually Stachybotrys chartarum, which needs sustained wetting of cellulose-rich material — gypsum plasterboard, wallpaper, cardboard-backed ceiling board — rather than a passing damp patch. Its presence is a reliable indicator of a long-running water problem, which is the real reason to take it seriously.

The established health evidence links indoor damp and mould exposure with respiratory symptoms, asthma exacerbation and allergic rhinitis. This matters in South Africa, which has a high asthma burden. The evidence does not support the more dramatic claims sometimes used to sell remediation packages.

The practical position: it is a genuine health concern, particularly for children, elderly occupants and anyone with asthma or a compromised immune system, and it warrants prompt repair of the water source. It is not a reason to panic or to accept a quote you have not had explained.

In a sectional title scheme, the split follows the Sectional Titles Schemes Management Act. Damp entering through common property — the roof, an external or boundary wall, a parapet, or common plumbing — is the body corporate’s responsibility to repair, even though the damage appears inside your unit. Damp generated within the section, such as condensation from poor ventilation or a leak from your own fittings, is the owner’s. A written inspection report identifying the mechanism is what settles this argument, and it is frequently the reason one is commissioned.

For rentals, the Rental Housing Act obliges a landlord to provide a dwelling fit to live in. Structural damp is generally the landlord’s to fix; condensation driven by how the property is occupied and ventilated is more often the tenant’s contribution. In practice most disputes are a mix of both, and the Rental Housing Tribunal will want evidence rather than assertions.

On a sale, the voetstoots clause protects a seller against defects they did not know about — it does not protect a seller who knew of a damp problem and concealed it. The Property Practitioners Act now requires a signed mandatory disclosure form on most transactions, and painting over active mould shortly before listing is precisely the conduct that turns a defect into a claim.