Building with ETFE films

Transparent ETFE cushion roof in Mexico for the Paseo Acoxpa

After its market introduction in the 1970s, ETFE foil long lingered in the niche. Today it is one of the most popular materials for large-scale, transparent facades or roof structures. Combined with state-of-the-art technology, it establishes a new language of form and diversity in architecture. The transparent, often cushion-shaped structures are not only façades or roofs to protect against weather, but also a medium for light, color, and form language, and they integrate intelligent shading systems. Thus, ETFE foil constructions offer added value for every building while meeting the high requirements of sustainable, modern architecture.

Properties of ETFE foils

These constructions became possible thanks to the special properties of the material ethylene-tetrafluoroethylene (ETFE), which is used in textile architecture in the form of ETFE foils. The most important properties are high transparency of about 90% while still having very low own weight and a thickness of 80–300 µm. The chemical bond of ETFE foil is extremely stable and resistant to external influences; it has very good elongation properties and is characterized by high tear resistance. The material is chemically inert — it remains stable for decades without changing color or strength and is insensitive to typical temperature fluctuations. Advantageous for many applications is that the foil transmits short-wave UV radiation, promoting plant growth. The use in greenhouses, biosphere reserves, or swimming pools is therefore particularly versatile.

The material is resistant to heat and cold and only deforms at around 200°C. In case of fire, ETFE retracts from the fire source; the opening created in the foil allows smoke and gases to escape from the building. ETFE foils comply with European fire class B-s1,d0 — thus flame retardant and self-extinguishing. Because of its low mass, the material has a low fire load, low smoke development, and no burning drips. Due to constant material properties in production, different material batches can be used together in a single construction project, which is a major advantage for large projects compared with other membranes.
ETFE foil is usually produced transparent but can also be white or colored. The foil can be printed with various dot patterns, allowing project-specific transmission levels to be set. The ETFE derived from petroleum is recyclable due to its pure production, offering good chances for a second life in industry. ETFE is very durable and resistant to hail and wind. In addition, the surface has self-cleaning properties and is thus very low-maintenance. When used as wall or ceiling elements, the material also has positive acoustic properties for interior spaces due to its low reverberation time.

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ETFE structures and areas of application in textile architecture

The ETFE foil is a material that is used without reinforcement fabric and thus offers the highest transparency. ETFE foils are typically used for facades and roof constructions where a high light, UV, or heat input from solar radiation is desirable. This is the case, for example, in greenhouses, animal enclosures, or in swimming halls, sports facilities, and public places such as shopping centers. Solar heat gains can be significantly reduced project-specifically through coloring and printing. Constructions that are optimally suited include domed or atrium roof structures. These constructions are often characterized by large spans with few supports. Compared to glass, ETFE constructions can contribute to material and cost savings through lightweight secondary structures.

In ETFE constructions, a distinction is made between single-layer and multi-layer configurations. Single-layer areas are mechanically pre-stressed, while multi-layer constructions are installed in the form of pneumatic ETFE cushions, called pneu. The formation of the cushion grid is often crucial to the design of the structure and gives each construction its unique character. The cushion layers are welded at the edges and screwed to the slender secondary structure via ETFE connection profiles. This transfers loads to larger primary supports and conveys them into the building. An example of an exciting ETFE construction with diamond-shaped cushions is our Acoxpa project, completed in 2018 in Mexico and serving as the roof of a shopping center. An example of elongated cushions is the Cabo Norte project. To maintain constant air pressure in the cushions, a blower responds to external influences such as snow or wind loads, but also ensures a permanently stable envelope in case of air loss due to damage in the cushions. An intermediate air dryer can prevent the formation of condensate. A comprehensive safety concept is part of every planning and includes measures in case of fire as well as the avoidance of water pockets during air pressure loss in one or more cushions.

Special attention in ETFE constructions is paid to summer heat protection to avoid overheating of interior spaces. By using colored or so-called IR-cut material, solar radiation and thus heat input into the building can be reduced. In addition, ETFE foil can also be printed and, through reflective color layers, contribute to a reduction. Further shading options arise from mechanical control of multi-layer cushion chambers. This allows control of both heat input and winter heat loss. The number of chambers has a decisive influence on the U-value of the ETFE construction. Typically, the span of the strip-shaped cushions is 3–4 m with almost any length. Larger spans can also be realized without a secondary carrier by arranging reinforcement cable constructions on the top and bottom of the cushion. For example, 3dtex GmbH has planned and built the world’s largest ETFE cushion roof to date, with a cushion chamber of 45 m in diameter. For the Oxígeno Erlebniswelt in Costa Rica, an atrium with a two-layer cushion was roofed in 2018. The loads occurring in the dome are discharged from the ETFE foil to the edge supports via a cable network. This is an advancement of the technology that 3dtex developed for the covering of the La Victoria shopping center.

Our services for ETFE projects

3dtex GmbH is a general contractor for ETFE constructions and can look back on numerous pioneering construction projects in this specialist field of lightweight construction. We offer consulting, preliminary studies, and designs through to the manufacture of your ETFE construction project. We accompany you every step of the way through to implementation and installation.

Basic evaluation, preliminary design, and design for ETFE structures
Cost calculations for ETFE structures and binding offer for the entire project (based on an agreed design)
Shape determination and optimization
Structural analysis of the ETFE structure and all connecting elements and the supporting structure
Technical consulting for blowers and ventilation systems
Development of a safety concept for your ETFE construction
Manufacture and assembly of all ETFE elements from a single source
Assembly management for ETFE projects
Support and maintenance for completed ETFE constructions

ETFE connection profiles from 3dtex

As a general contractor for ETFE constructions, we are constantly involved in the development of special solutions and develop our own connection and node elements, filters, and valves for this purpose. In this context, we developed a fully optimized ETFE connection profile in 2024, which is used in our projects but can also be purchased for external projects. We currently have an ETFE double bead profile and an ETFE single bead profile in our range. We would also be happy to advise you on connections, ETFE sealing profiles, covers, screws, etc.
> You can find more information about our keder profiles on the product page.