Louvered pergolas in Bali

We build louvered systems in extruded aluminium: blades that rotate through roughly 135 degrees, perimeter beams that double as gutters, and downpipes concealed inside the posts. Manual crank versions suit small terraces and have nothing electrical to fail. Motorised systems add an actuator per bay, a remote or wall panel, and optional rain and wind sensors that close the roof while you are still on the beach and reopen it once the squall has passed.

Everything else is corrosion engineering. Blades, beams and posts are powder-coated over a seaside-class pre-treatment, fasteners are A4 stainless, and actuator housings are sealed to an IP rating that survives being rained on sideways. The cheap systems arriving on the island look identical on day one and are seized, streaked and rattling by their third wet season — almost always because somebody saved a few hundred thousand rupiah on screws.

Closed mode is a roof, so we size it like one

A four-by-six-metre louvered roof is twenty-four square metres of catchment. At the 80–100 mm per hour this island produces several times a season, that is roughly forty litres a minute arriving in the perimeter beam, most of it in the opening minutes of a storm. Systems sold with one 50 mm outlet overflow at the blade line and pour straight down a guest's back.

So the closed pergola gets treated as a small roof: outlets sized to the catchment, at least two downpipes on anything above roughly twenty square metres, a fall built into the beams, and a discharge that reaches a drain or a soakaway instead of the terrace tiles. It is unglamorous arithmetic, and it is the single biggest difference between a system that works in a downpour and one that only works in a brochure photograph.

Manual, motorised, or a bit of both

Manual crank systems are mechanically simple, cost around a third less and have no electronics to fail. On a small terrace that a family adjusts twice a day they are frequently the better buy, and we will say so rather than upsell a motor nobody needs.

Motorisation earns its keep on larger roofs, on anything above head height, and on rental properties where guests will never touch a crank handle but will certainly complain about rain on the sofa. Where we do motorise, each bay gets its own actuator so one failure never immobilises the whole roof, cabling runs in conduit instead of being clipped to the frame, and the sensor package is set conservatively — closed on the first rain, held closed until the wind sensor agrees it is safe. Spare actuators and gaskets sit in our store, because a part on a boat from Europe is a wet season lost.