How to Make a Tension Fabric Structure

Create colorful shading designs with tension fabric structures.

A tension fabric structure is a two-dimensional, walled structure where the skeleton of the structure places tension on both the outside edges of the structure and the covering fabric. Originally a simple offshoot of the canvas canopy as a shading screen, tension fabrics have evolved over the last several decades into complex and multivariate structures. They are applied to much more than simple shading requirements. Tension fabric structures are now used to enclose, cover and protect everything from aircraft to amphitheaters.

Things You'll Need

• T-square
• Paper
• Pencil
• Tape measure
• Heavy tensile-strength nylon material
• Straightedge
• Permanent marker
• Electric scissors
• Sewing machine
• 3/8-inch-by-12-foot high-alloy aluminum tubing
• .292-inch carbon fiber flex-poles
• Reciprocating saw
• .292-by-2-inch ferrules
• 1/8-by-1/4-inch grommets
• Grommet pliers

Instructions

1. Create the individual fabric panels by first laying out their lateral dimensions. Sketch out the dimensions on white paper with a T-square and pencil. Identify the structure lines that will be curved (flexing edges) by adding a wavy line over the straight line. (Note: Curved in this context refers to the process of bending a fabric panel into a tunnel or barrel-shaped curve and holding it in that position with straight, rigid connectors.) Begin with squares and rectangles, working toward trapezoidal, triangular and free-form designs. Write down the distance that the panel will be curved into, in feet and inches, on the panel design. For example: if an an 8-by-12-foot panel will be curved to fit into a smaller than 8-foot space, the length of that space must also be noted.

2. Measure the nylon fabric to the dimensions designed with a tape measure and straightedge. Mark the cut boundaries with a permanent marker, adding 2 inches to all the dimensions, for the hemmed edges of the fabric panel.

3. Use heavy, electric scissors to cut the nylon fabric along the boundaries of the laid-out panel.

4. Run the edges of the fabric panels through a sewing machine and stitch a 1/2-inch hem at all edges. Hem the non-flexing edges first. When hemming the flexing edges, where the fabric panel will be curved, run the hem up to but not over (enclosing) the adjacent hem at the corners.

5. Measure and mark the lengths of the poles needed on all edges of the fabric. Mark the needed lengths of rigid poles (for non-flexing edges) on 3/8-inch aluminum tubing. Mark the required lengths of flexible poles (for flexing edges) on the carbon fiber flex-poles. These poles are similar to the flex-poles used in mountaineering tents but substantially more rigid and able to withstand a greater degree of bending.

6. Cut all the lengths of both the aluminum tubing and the carbon fiber flex-poles with a reciprocating saw. If the lengths of the flex-poles are not long enough, insert connecting ferrules into the ends and connect additional lengths to meet the desired length.

7. Insert the aluminum tubing into the appropriate-side hem tubes. There should be a 1/2-inch squeezable hem area on both ends of the hem. Punch a hole in the square end at the corners of the fabric and press a 1/8-by-1/4-inch grommet in the center of it.

8. Insert a pointed ferrule (connecting tip) on both ends of the carbon fiber flex-poles. Slide them through the hems on the flexing edges of the fabric and insert the ferrules into the grommets.

9. Place the tension fabric panel against the ground, with a non-flexing edge touching it. Pull down the other non-flexing edge and the flexing edges will curve, taking the material with it -- forming a barrel or dome-shaped structure. Place the tension fabric assembly into its intended fit location and bend it into position.

Tips & Warnings

• Bright colors make for bolder and more exciting designs.

• Use caution when working with materials under stress or tension.

References

• "The Tensioned Fabric Roof "; Craig G. Huntington; 2004