Coastal homes get damp because salt-laden air, wind-driven rain and high humidity drive moisture into exterior walls faster than an ordinary paint can shed it. The fix is a two-sided system: seal the outside with a salt-air-resistant waterproof coating such as Shield, and manage any interior damp with Damp Proof once the source is sealed. From Table View to Bloubergstrand, this combination handles the conditions that defeat standard paint.
Why coastal homes get damp
Three coastal forces drive damp: airborne salt, wind-driven rain and humidity. Salt settles on walls and draws moisture from the air, wind-driven rain forces water into hairline cracks that a still-air wall would shed, and constant humidity slows drying so walls stay wet longer. Styrenated and low-binder paints break down quickly under this load, which is why coastal walls chalk and peel early.
The three coastal damp problems
- Salt attack. Hygroscopic salts in the air and masonry pull moisture out of humid air, keeping the wall permanently damp and lifting paint.
- Penetrating damp. Wind-driven rain is pushed through hairline cracks and porous plaster that would stay dry inland.
- Condensation. High indoor humidity meets cold internal walls and forms surface moisture and mould, worst in winter.
Which walls suffer the most
Sea-facing walls, parapets and window reveals take the worst of the salt and wind-driven rain. On the Cape west coast the north-west-facing walls catch the winter storms head-on, and parapets, chimneys and flashings are the common entry points. These are the areas to seal first.
The coastal repaint system (step by step)
- Wash off salt and algae with fresh water and a stiff brush. Salt left on the wall stops any coating bonding.
- Treat mould and algae with a biocide and let it work.
- Repair cracks over about 2 millimetres (mm) with a flexible filler.
- Prime bare or chalky plaster with Solvent-Based Plaster Primer.
- Apply two coats of Shield, a pure-acrylic, salt-air- and ultraviolet (UV)-resistant waterproof membrane that flexes over hairline cracks.
- Treat the interior face with Damp Proof where damp already shows inside. Never use a styrenated paint on the coast.
How often to repaint on the coast
Coastal exposure shortens paint life: ordinary exterior paint lasts 2 to 3 years, while a quality waterproof membrane like Shield lasts about 10 years. Inspect the walls once a year, wash off salt build-up, and touch up early edges before they spread. A small repair at year 7 or 8 buys several more years.
Colour and coastal heat
Light and heat-reflective tints run cooler on a sun-and-salt-exposed wall and show salt bloom less than dark colours. On a hot sea-facing roof, a heat-reflective grade such as Heat Reflect lowers surface temperature.
Frequently asked questions
Why is my coastal house always damp? Salt air, wind-driven rain and humidity push moisture into the walls faster than ordinary paint sheds it. A salt-air-resistant waterproof coating fixes the exterior.
What paint is best for coastal homes? A pure-acrylic waterproof membrane such as Shield, never a styrenated paint, on a well-prepared, salt-free surface.
Does salt damage paint? Yes. Salt draws moisture and lifts low-binder and styrenated films. Wash walls with fresh water and use a pure-acrylic coating.
How do I remove salt from a wall before painting? Wash it down with fresh water and a stiff brush, let it dry, and prime before coating.
Where to buy
Shop Shield and Damp Proof, or read the complete waterproofing guide. Visit our Table View, Cape Town paint shop or call +27 84 985 6141.
