Some of the world’s most distinctive buildings use untraditional roofing systems to keep the elements at bay. Instead of a traditional rigid structure, they rely on an underlying skeleton topped by a lightweight, flexible membrane made of fiberglass with a coating of polytetrafluoroethylene (PTFE). The resulting designs are delicate and airy, but their appearance is deceptive: they’re rugged enough for decades of use in harsh conditions. They are also visually stunning, as evidenced by iconic buildings. Why do architects choose a structural membrane instead of a conventional roof? Here are some of the principal reasons, drawing from the Sigma product line to illustrate the points discussed.
A membrane structure lets the architect combine distinctive and elegant forms into a unique structure, combining a variety of panel shapes into endless geometric configurations to address complex aesthetic and functional challenges. Compared to a traditional roof, the membrane is lightweight and requires a lighter support structure, which translates into fewer columns and longer spans. The options for the underlying structure include tensile or tensegrity configurations: a grid shell, a frame or a cable net, among others. An alternative approach uses air pressure to maintain the shape of the membrane, resulting in a design that is economical to build, operate and maintain.
A membrane can include a titanium dioxide (TiO2) photocatalytic topcoat with self-cleaning and air purifying properties, such as Sigma’s EverClean. This coating combines with the sun’s ultraviolet (UV) radiation to produce hydroxy radicals and superoxide radicals that oxidize (decompose) all organic substances. The residues are washed away by rain. In addition, the EverClean coating decomposes two atmospheric pollutants, nitrogen oxide (NOx) and sulfur dioxide (SO2). These pollutants, contained in exhaust gas and smoke, are major contributors to ozone and acid rain. The reduction process releases nitrate ions that are washed away into the soil to help in plant fertilization.
A PTFE surface has very low surface tension, making it stain-resistant. Rain or a water spray easily removes accumulated dirt and dust. The membrane’s easy-to-clean surface requires very little, if any, maintenance during its lifetime and will never need painting.