Guwahati Tensile Structure

A deep atrium in a heavy concrete building can be gloomy. The brief for a skylight assembly is to open the roof to the sky and bring usable daylight down to the floors and walkways below — without the weight, the solar heat gain and the glare that a large area of glass would bring, and without compromising the roof against the monsoon.

Ekra Decor’s scope covered the membrane elements end to end: the 3D design of the faceted skylight geometry, the supporting steel that frames each opening, fabrication of both, and installation into the concrete roof, sealed and tensioned.

Each skylight is a small tensile structure in its own right. A steel frame lines the opening in the concrete, and the membrane is stretched over it and pre-stressed into a faceted, multi-point shape — the facets keep the fabric taut and give the rooflight a crisp, sculptural form when seen from below.

Translucency is the whole point of the material choice. A PVC- or PVDF-coated fabric transmits a controlled fraction of the daylight and scatters it, so the atrium gets bright, shadow-free light and far less solar heat than clear glazing would let in. The perimeter of each element is detailed as a weathered upstand so water is thrown clear and the roof stays sealed. Ekra Decor designs the framing steel to IS 800 and checks each element for wind and rain loading to the applicable Indian codes.

The steel frames are fabricated and hot-dip galvanised in the workshop and the membranes are cut to their faceted patterns and welded into finished pieces. On site, the openings in the concrete are formed and prepared, each steel frame is set and sealed into its opening, and the membrane is fitted and tensioned.

The work is done from above and below with the building largely weathertight throughout, and each element is left as a finished, sealed, tensioned rooflight.

The building gained a set of membrane skylights that fill the atrium with soft, even daylight while keeping the roof sealed and the solar heat down. Tensioned-fabric rooflights hold their form for years and need only occasional cleaning.

Ekra Decor builds membrane skylights and internal tensile features alongside its outdoor structures. See more finished work on the projects page, or read about tensile structures in Guwahati.