Roofing Structure

ETFE (Ethylene tetrafluoroethylene) is a lightweight material that is a superb alternative to glass. It is a popular choice for applications where high light and UV transmission are required, such as:

• Large-span roofing
• Skylights
• Facades

ETFE foil demands less structural steel support than traditional glazed systems, resulting in an easier installation, and typically a lower cost alternative. It is often considered a value-engineered option over glass roofing.

ETFE foil roofs can be supplied as a single layer membrane supported by a cable net system or as a series of pneumatic cushions made up of between two and five layers of ETFE.

ETFE Foil is a plastic polymer related to Teflon and is created by taking the polymer resin and extruding it into a thin film. Transparent windows are created either by inflating two or more layers of foil to form cushions or tensioning into a single skin membrane. Weighing approximately 1% of the weight of glass, ETFE (both single ply membranes as well as multiple layered ETFE cushions) are extremely light weight.

Lighting

Alongside its low weight, another major benefit of ETFE is its high translucency. Transmitting up to 95% of light, it is chosen for projects such as stadia with grass surfaces where full spectrum natural light and UV transmission is essential to maintaining plant growth.

The ETFE film also absorbs a large proportion of infra-red light, a quality which can be exploited to improve buildings energy consumption. When high levels of light transmission are not required, ETFE film can be printed or fritted, with a range of patterns to reduce solar gain while retaining transparency.

The base material of an ETFE installation is very transparent. However, the ETFE Foil can be treated in a number of different ways to manipulate its light transmission properties. These include printing, tinting, surface treatments, radiation and adding additional layers.

Sound Absorption

With an extremely low mass, ETFE cushions limit the amount of reverberation within a room by absorbing the acoustics.

The exact sound levels within an enclosure will depend on the properties of the cushions and the project (e.g. size/scale of room, incline of the pillows, materials used inside, and the span of the pillows).

Fire Safety

ETFE is a non-combustable material under the Building Code of Australia, as it vaporises, and doesn’t drop flaming pieces of material. ETFE foil is 100% recyclable, including the aluminium extrusions. The material contains roughly 5% recycled materials, and since it is an extruded thermoplastic, it doesn’t degrade.

ETFE has been extensively tested for its performance under fire conditions at various institutions around the world and complies with the relevant national codes. It has been tested to AS1530 Part 2 and 3 as self-extinguishing with no burning drops.

ETFE has the unique property of self-venting plumes over 200ºC into the atmosphere. As a result it prevents the build-up of high temperatures under the roof; and prevents the potential catastrophic structural collapse of the primary structure.

In situations where the plume does not reach 200ºC, we can fit ETFE with operable smoke vents to ventilate the products of combustion operated by the building management system.

Maintenance

ETFE Foil has an excellent life expectancy as it is unaffected by UV light, atmospheric pollution and other forms of environmental weathering including marine spray.

While no ETFE structures have been in place for long enough to gain a true understanding of the full life cycle of the foil, the material has been extensively researched and tested in a laboratory environment and out in the field.

These tests have concluded that no degradation or loss of strength has occurred and there is no sign that the material will become brittle or discolour over time. As a result, it is anticipated that the material has a life expectancy in excess of 50 years.