Depending on the design, tensile structures and umbrellas may look complicated, but at their core – they are made of two essential components: the frame and the tensile fabric that gives the structure it’s iconic shape and appearance.
Structural fabrics used for this purpose have to be strong enough to withstand the tension. Plus, they should also be durable enough to withstand outdoor weather conditions.
In order to improve the properties of various fabrics and make it suitable for tensile structures, they need to be coated with various materials. In this post, we’ll get to know the different coatings used for tensile fabrics.
Polyvinyl Chloride Coating Polyester (PVC)
The PVC or Polyvinyl Chloride coating is usually used to coat polyester fabric to make it suitable for tensile structures. It is one of the most commonly used mainly because of it’s cost effectiveness. It is selected for either temporary or permanent structures. Some also use them for architectural umbrellas.
This tensile fabric is pliable, soft, and flexible yet it is durable and of high strength. The fabric is also water-proof and there are many colors to choose from. Fabrics treated with PVC coating are also known to be fire, UV, and stain-resistant. However, they can stretch due to load so it needs to be re-tensioned periodically.
PVC coated polyester will usually have a lifespan of up to 25 years depending on various factors like the quality of PVC coating and the extent of exposure to outdoor conditions like changes in weather or pollution. This fabric is relatively easy to clean and is considered low maintenance.
In some cases, lacquers or other additional topcoats can be applied to this fabric to further increase its lifespan and reduce the frequency of the maintenance schedule. Such topcoats would include polyurethane-acrylic or acrylic solutions, polyvinylidene fluoride coating, and, polyvinyl fluoride film lamination.
Fiberglass Teflon Coated (PTFE)
Fabrics known as PTFE are woven fiberglass membranes that are coated with Teflon or polytetrafluoroethylene. They are preferred for permanent tensile structures that will require a long lifespan. It has excellent resistance against weather-related damages, temperature, UV, and chemicals. Additionally, this is strong and highly durable. It has a long lifespan going beyond 25 years.
This fabric has an off-white or sometimes slight brown color before installation. This is simply due to how the fabric was manufactured. However, upon exposure to direct sunlight, it turns to a milky white color within several days. It also has excellent reflective properties without transferring much heat. This makes it a great fabric for structures intended to give shade and reduce heat due to sun exposure.
It is considered a self-maintaining fabric because of the Teflon coating. With it, a smooth surface is produced and when it rains, the dirt could be easily washed off. This is because Teflon allows the fabric to resist moisture absorption. This can significantly reduce the need for frequent cleaning. Also, this doesn’t creep so there is no need to re-tension it, unlike the PVC coated polyester fabrics. However, this fabric is more expensive than the PVC coated one. It also needs to be spot-welded or heat-sealed at the seams.
Silicone Coated Fiberglass
A more affordable alternative to PTFE is silicone-coated fiberglass. It has high tensile strength but it is still very flexible and lightweight. The material also has good fire-resistance ratings and can effectively block UV-B light. It does allow UV-A light to penetrate through it so that photosynthesis can still happen on plants.
This puncture and tear resistant material is also available in various colors and translucency. To install it, you’d need to make use of an adhesive with the seaming process. The adhesive can take time to cure as compared to those used for the PTFE material.
Mesh Type Materials
Aside from coated fabrics, mesh type materials are also used in tensile structures. High-density Polyethylene or HDPE is one of them. This material is great for those who are in areas where hot and dry climates persist. It is of high tensile strength, UV stable, and fire-resistant. The lifespan of this material can reach up to 10 years and is installed by sewing with industrial machines. However, do take note that these are not waterproof.
Ethylene Tetrafluoroethylene (ETFE)
ETFE is a film or foil and is not a fabric. It is manufactured in sheets and can be used as a single layer. However, it is more commonly used as a multi-layered cushion. With this, multiple sheets are used and between them are air-filled pockets. The pressure is maintained by an inflation system that is the size of a washing machine. This gives the material structural stability. Unlike the other tensile fabric and materials, this is transparent.