A tensile membrane structure firm

Today’s typical event tent uses a flat PVC coated woven polyester textile draped over a galvanized steel frame. The steel frame stands alone, in compression, as the essence of the structure. The flat fabric panels are mounted on the steel frame and must be pulled tight to remain flat in the wind, an impossible task because they are flat, so the fabric is prone to flutter in the wind.

The ‘tensile structure’ in contrast is stabilized with tension rather than a compressive steel frame.  One popular design uses large masts to lift the fabric, with tension forces pulling in opposite directions to draw the tent into form. Think of the Denver Airport. The masts are the compressive elements. Teflon coated fiberglass woven fabric and cables are the tension elements which enable the canopy to cover broad expanses.

A smaller tensile structure is typically built from fabric woven with polyester thread. The flat fabric is patterned and joined into a shape characterized by anticlastic curvature with the final form set by the tension of the outer cables. The final product is stunning, but singular in application and care must be taken to avoid tensioning outside of the engineered design. Frei Otto’s  Tanzbrunnen from 1957 is a classic.

Instead of weaving, we use a circular knit manufacturing technique with high tensile strength polyester thread. This creates just enough stretch in the fabric for the structure to be pulled into shape under tension, not ripped apart as can happen when a woven fabric is tensioned in a direction and force for which it wasn’t designed.

It’s difficult to detect the stretch with a small fabric sample, but the effect on a broader tent is quite evident as riggers apply tension. What starts as a flat panel is pulled into shape in the last stage of the pitch. Tension is applied to create the final form and the anticlastic curves that enable the stretch tent to withstand the forces of nature.

South Africa is to stretch tents as the fertile crescent is to civilization. A few decades ago, inspired by the Bedouin tents of Northern Africa and fueled by the innovative spirit endemic to Southern Africa, intrepid inventors improved an ancient art.

They adopted cutting edge fabric innovations and transformed the tenting industry of a continent. We lived in South Africa for six years as these stretch tents grew in popularity. They just fit with the culture and climate – quite literally tailor made for the environment.

Upon returning to Colorado, we brought the technology with us, adapting as necessary to fit the Rocky Mountain climate.  We’ve been growing ever since with rentals, sales and custom development. Today we serve a growing loyal customer base and a market awakening to the superior technology of stretch.

We’re thankful to again be part of the Colorado outdoor ethos, and especially thankful to our many South African friends who pioneered this technology in Africa & beyond. We’re heavily indebted to them so we’ll stay true to the sweeping lines and robust engineering that define the stretch tradition.