ETFE Cushion Systems
ETFE Cushion Systems for Large-Span Roofs and Buildings
ETFE cushion systems provide a lightweight, transparent solution for large-span roofs, skylights, atriums, stadiums, transportation facilities, commercial buildings, and other architectural applications. Unlike single-layer ETFE membranes, ETFE cushions use multiple layers of ETFE foil separated by controlled air pressure to create a lightweight three-dimensional building envelope.
The appropriate configuration depends on the project’s geometry, structural requirements, daylighting objectives, environmental conditions, thermal performance, and overall design requirements. SkyTensile provides ETFE system solutions for projects that require engineered coordination between membrane configuration, supporting structures, fabrication, and installation.
What Is an ETFE Cushion System?
An ETFE cushion is a pneumatic membrane system made from two or more layers of ETFE foil. The foil layers are welded around their perimeter and connected to an engineered supporting frame. A controlled low-pressure air supply maintains the cushion geometry and provides the pneumatic stability required for the system.
Unlike a single-layer ETFE membrane, which is mechanically tensioned over a supporting structure, an ETFE cushion uses air pressure to maintain the spacing and shape between its foil layers.
The complete system typically includes:
ETFE foil layers
Welded cushion panels
Perimeter framing and connection profiles
Supporting steel, aluminium, or other engineered structures
Air supply and distribution systems
Pressure monitoring and control
Drainage and edge detailing
Project-specific structural and environmental design
The cushion, supporting structure, edge connections, and inflation system therefore need to be considered as one coordinated system rather than as separate components.
How Do ETFE Cushion Systems Work?
The structural form of an ETFE cushion is created and maintained by controlled air pressure.
Air is supplied through a dedicated inflation system and distributed to the individual cushions. Pressure monitoring and control help maintain the required cushion geometry as environmental conditions change.
A typical ETFE cushion system includes:
ETFE foil layers — lightweight foil forms the transparent membrane envelope.
Welded edges — the foil layers are fabricated into sealed cushion units.
Perimeter framing — the cushion is restrained around its edges through engineered profiles or connection systems.
Air distribution — air is supplied through pipes or ducts connected to the cushion system.
Pressure control — the air-handling and control system maintains the required operating pressure.
Primary supporting structure — steel, aluminium, cable-supported, or other structural systems transfer loads from the cushions into the building structure.
The required air pressure is project-specific. It depends on factors such as cushion geometry, dimensions, support conditions, wind and snow loads, and the overall structural design. Published ETFE systems commonly operate at low pneumatic pressures, but the final design pressure should always be established through project-specific engineering rather than assumed from a generic value.
Single-Layer ETFE vs. ETFE Cushion Systems
ETFE can be used in both single-layer and multi-layer configurations. The choice should be based on the requirements of the building rather than simply on the number of membrane layers.
Single-Layer ETFE
A single ETFE membrane is mechanically restrained or tensioned over a supporting frame, cable system, or other engineered structure. It does not require continuous inflation.
Single-layer ETFE can be suitable for:
Canopies
Skylights
Semi-open spaces
Lightweight roof coverings
Facade applications
Projects where thermal insulation is not the primary requirement
Its relatively simple system configuration can make it appropriate where transparency, low weight, and a lightweight enclosure are the main design priorities.
Double-Layer ETFE Cushion
A double-layer ETFE cushion consists of two ETFE foil layers separated by an air chamber. Continuous air supply maintains the cushion geometry.
It can be considered for:
Commercial atriums
Large-span public buildings
Enclosed architectural spaces
Skylights and roof systems
Projects requiring a combination of daylight and improved thermal performance
Multi-Layer ETFE Cushions
ETFE cushions can also incorporate three or more foil layers, creating multiple air chambers. Additional layers can provide designers with more options for thermal, daylight, solar-control, and visual performance.
The appropriate number of layers should be determined from the project’s actual requirements. More layers should not automatically be interpreted as a universally better solution; the complete foil build-up, cushion geometry, framing, edge details, and environmental conditions all affect final performance.
Published systems commonly use two to four layers, while other project-specific configurations may also be possible.
ETFE Cushion Configurations and Performance
The configuration of an ETFE cushion can be customized according to the architectural and engineering requirements of the project.
Key variables may include:
Number of ETFE foil layers / Foil thickness
Cushion dimensions and geometry / Clear, tinted, fritted, or printed foil
Solar-control requirements / Daylight transmission
Thermal performance / Supporting structure
Edge and connection details / Inflation and control requirements
Daylight and Solar Control
One of the major architectural advantages of ETFE is its ability to introduce natural daylight into large enclosed spaces. Depending on the selected foil, printing, frit pattern, tint, and layer configuration, designers can adjust the optical performance of the system.
For more advanced applications, printed or specially configured intermediate layers can also be used to control solar transmission. Some ETFE cushion systems use air pressure to change the position of printed intermediate layers, creating an adjustable shading effect.
Thermal Performance
The number of foil layers and the complete cushion and framing system influence thermal performance. Additional air chambers can improve insulation compared with a single foil, but the final U-value of a roof or facade depends on the complete assembly, including cushion geometry, perimeter profiles, framing, and thermal bridges.
For this reason, thermal performance should be calculated for the specific project rather than based on a generic ETFE cushion value.
Key Design Considerations for ETFE Cushion Systems
Successful ETFE cushion projects require coordination between architectural design, structural engineering, membrane fabrication, and the pneumatic system.
Cushion Geometry
Cushion dimensions, shape, and layout affect membrane behavior, supporting structure, drainage, fabrication, and the overall architectural appearance.
Structural and Environmental Loads
The supporting structure and cushion system should be designed according to the project’s geometry, wind and snow loads, site conditions, and applicable design standards.
Inflation and Pressure Control
ETFE cushions rely on a controlled air supply to maintain their designed geometry. The system may include air-handling equipment, distribution pipes, pressure monitoring, and control equipment, depending on project requirements.
Edge Connections and Drainage
Perimeter profiles and connection details must coordinate the ETFE cushion with the supporting structure while allowing for drainage and interfaces between adjacent cushions.
ETFE Cushion Applications
ETFE cushion systems are commonly considered for:
- Commercial atriums and shopping centers
- Stadiums and sports facilities
- Airports and transportation hubs
- Public and landmark buildings
- Large-span skylights and enclosed public spaces
The appropriate configuration depends on the project’s architectural, structural, environmental, and operational requirements.
Selected ETFE Cushion Projects
SkyTensile has applied ETFE cushion systems across different building types and configurations, from commercial and cultural buildings to stadiums and transportation infrastructure.
Oran Park Library — 2-layer ETFE cushion facade system integrated with a custom folded-plate steel structure. [View Case Study →]
Qingdao Youth Football Stadium— Multi-layer ETFE cushion system developed for a large-span sports stadium roof. [View Case Study →]
Jinan Airport T2 Terminal — Multi-layer ETFE cushion dome system developed for a large transportation hub. [View Case Study →]
Hangzhou Xiaohe Park — ETFE pneumatic cushion canopy for a large-scale cultural and commercial destination. [View Case Study →]
Hangzhou Bogu shopping Mall – Multi-layer ETFE cushion dome system developed for a shopping mall [View Case Study →]
Design, Fabrication and Installation
SkyTensile approaches ETFE cushion projects as an integrated system:
Concept Development → System Selection → Engineering Coordination → Membrane Fabrication → Installation → Air System Commissioning
The process may involve coordination of cushion geometry, supporting structures, membrane specifications, edge details, drainage, inflation systems, and site conditions.
ETFE cushions are fabricated by welding the foil layers into the required geometry and connecting them to the engineered perimeter system. After installation, the pneumatic system is checked and commissioned to maintain the required operating condition.
ETFE Cushion System Cost
The cost of an ETFE cushion system depends on factors including foil configuration, cushion geometry, supporting structure, edge profiles, inflation equipment, engineering, fabrication, installation, project location, and overall scope.
For a broader overview of the factors affecting tensile membrane project pricing, see our Tensile Structure Cost Guide.
Frequently Asked Questions
An ETFE cushion system uses two or more layers of ETFE foil maintained in shape by controlled air pressure and connected to an engineered supporting structure.
Single-layer ETFE is mechanically supported without continuous inflation, while an ETFE cushion uses multiple foil layers and controlled air pressure.
ETFE cushions commonly use two or more foil layers. The appropriate configuration depends on the project’s structural, thermal, daylighting, and solar-control requirements.
Get an ETFE Cushion System Proposal
Planning an ETFE roof, atrium, skylight, stadium enclosure, or other large-span architectural project?
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