The physics, simply put
An interior blind manages heat that has already made it into the room. An external venetian stops most of it outside, at the glass itself. On a Blue Hills home with a big north-facing living wall or a west-facing study catching the afternoon sun over the paddocks, the difference in indoor temperature is dramatic — it’s the same principle European and high-end local architects use to shade glass buildings.
What it actually is
Wide aluminium slats — typically in the 60–90mm class — run in guided side rails or cables, tilting and raising the same way an interior venetian does, just built for the outdoors. Finishes are powder-coated and engineered for weather exposure, which matters on an exposed elevation that gets full Highveld sun and the odd dust storm off open veld.
Effectively always motorised
An external blind lives outside, so it has to protect itself. Every install is effectively motorised, paired with a wind sensor that retracts the blind automatically the moment gusts pick up — the same logic that matters for awnings before an October storm front rolls through. It is not a system you want caught open in a highveld thunderstorm gust.
Worth planning for
This is a premium spend and a visible change to the facade, so if your estate runs an architectural or aesthetics committee, we build the submission pack around their colour and fascia rules before anything is ordered. It suits new-build planning best, though a considered retrofit is possible on the right elevation — we’ll tell you honestly if your facade isn’t a good candidate.
What external venetians cost
This is the premium end of the range and the numbers say so: a hand-operated system is R3,000 to R4,500 per square metre, fitted, R4,500 to R6,500 per square metre motorised. You are paying for guide rails, a head box, and fixings and finishes engineered to stand in full Highveld sun and summer hail for years rather than seasons — not simply for a slat outside the glass instead of behind it.
A wind sensor is part of the specification in our view rather than an accessory, and it appears as its own line on the quote. Small openings carry a minimum charge. There is also a question that comes before any price: the structure above the window has to carry the load, there has to be clearance for the rails, and on an estate the exterior appearance may need approval. All three are settled at the free measure, and if any one fails we say so and specify an interior answer instead.