Roof Paint Is Not Waterproofing
This costs us work to say, and we say it anyway.
Roof paint is a decorative coating with some UV resistance. It is thin, it is not designed to bridge a crack, and it has no capacity to hold back standing water. It will make a tired roof look new. It will not stop a leak.
The confusion is understandable, because roof paint is frequently sold as a waterproofing solution in Cape Town, often to people whose actual problem is a cracked ridge or a failed flashing. The roof gets painted, it looks excellent, and it leaks again in the first winter front.
If your roof leaks, the leak needs finding and fixing. If your roof is sound and looks tired, paint it. Those are two different jobs and they deserve two different conversations.
What a Clean Actually Shows You
The genuine value in roof cleaning, beyond appearance, is that it strips away everything hiding the roof condition.
Under moss, lichen and years of dirt we routinely find cracked tiles, hairline cracks in ridge bedding, corroded valley metal, perished flashing mortar and blocked valleys. None of it was visible before. All of it was doing damage.
Moss and lichen are not innocent. Moss holds water against the tile surface indefinitely, keeping it wet through summer as well as winter. It also lifts tile edges as it grows into joints, and it blocks valleys and gutters as it sheds.
So we treat a clean as an inspection with a visible result. You get the roof looking right, and you get an honest list of what is underneath.
High Pressure and Soft Wash
High pressure works on sound concrete tiles and cleans hard surfaces effectively. It also drives water under tile overlaps, so it needs care around ridges, valleys and any roof with failed underlay. Used carelessly it strips the surface off older tiles and forces water into the roof void.
Soft wash uses lower pressure with a biocide treatment. Slower, gentler, and better on older or fragile roofs, painted surfaces and anywhere high pressure risks damage. It also kills the spores, so regrowth is slower.
Which one your roof gets depends on the roof, not on which is quicker for us.
Asbestos Cement Roofs
We do not pressure-clean asbestos cement roofs.
Asbestos work in South Africa falls under the Asbestos Abatement Regulations, 2020. Pressure-washing an asbestos cement sheet abrades the surface and releases fibres into the air and onto the surrounding property, and it is not a permissible method. It is also not something a homeowner should do themselves with a hired machine.
Plenty of older Cape Town outbuildings, garages, carports and cottages have asbestos cement sheeting, and it is not always obvious from the ground. We can identify whether a roof is likely to be asbestos cement during the inspection, and if it is, we will tell you and refer you to a contractor registered for asbestos work rather than clean it.
That costs us the job. It is still the right answer.
When to Clean a Cape Town Roof
Late summer and early autumn. Cape Town winter rain runs June to September, and moss and algae do their growing through that wet period. Cleaning in March or April means going into winter with a clear roof, clear valleys and clear gutters.
Cleaning in the middle of winter is possible but less useful, because regrowth starts immediately and the roof cannot be inspected properly in wet conditions.
Roofs on the shaded southern side of a property, and roofs under trees in areas like Constantia and Bishopscourt, need it more often than exposed roofs. Shade plus damp equals moss.
