By Samuel J. Armijos
First and foremost, one needs to determine the appropriate fabric for the application. Today, structures are being designed that might, in theory, be considered permanent but are planned to be up for only 10, 15 or 20 years. Likewise, there are specific fabrics with life spans and warranties that meet or exceed the performance criteria specified. So choosing the right fabric for the right application should take precedence over anything else. The next step then becomes what to do with the components (steel, fabric, and cables) upon the end of their use. Steel, and most parts of the cables, can be recycled, and there are options for some fabrics, such as recycling or downgrading the material for another use.
To get the most out of a fabric structure in terms of life span, the key is to use the right material and have a service and maintenance plan. Fabrics with long life spans include Teflon™ and silicone-coated fiberglass, “hybrid” woven fiberglass, and vinyl-coated polyester. These fabrics have been used on structures around the world and have exceeded their intended life spans. They have been tested to see how they have survived over time, and results have shown little to no loss in their tensile strength, one of the most important criteria of a structure’s integrity. Twenty years seems to be the norm for these structures.
But what happens to these fabric structures as they reach their golden years, and how do you keep them structurally sound and looking brand new?
Most of today’s fabrics used for permanent applications have been designed with UV and mildew inhibitors, as well as topcoats with “self-cleaning” attributes. Self-cleaning really pertains to the ease in cleaning a material, because all membranes need periodic cleaning. Cleaning can be performed partly by rainfall, but in most cases requires a low-pressure wash, depending on the material chosen, its location, and the structure’s use.
However, maintaining fabric structures is not just about cleaning the fabric. The structural steel, cables and hardware need to be inspected on a regular basis, as these components play a significant role in the longevity of the structure. The best approach to maintaining structural components is to select components that have the most maintenance-free finishes. These finishes, of course, come at a cost. High-end factory paint finishes are much more desirable than field painting. Stainless steel hardware and cables for tie-downs and catenary cables are preferred over galvanized finishes. Inferior paint finishes and galvanized cables tend to introduce rust and other stains which can penetrate the membrane. Rust and stains are the two biggest concerns when maintaining the membrane.
“A tension fabric structure is a specialized and highly technical roof system,” says Larry Keene, service and maintenance expert at FabriTec Structures. To assure the full life expectancy of any fabric structure, an annual inspection should be performed. Most large-scale structures have a service and maintenance plan with the original fabricator or independent contractor and include annual inspections of all structural components and periodic cleaning. Similar to buying high-end electronics, with fabric structures, there is the opportunity to purchase extended warranties or service agreements, and that decision should be made sooner rather than later. According to Keene, “There is nothing worse than going through an unscheduled replacement or repair due to neglect.” By performing annual inspections, you are in a better position to budget and plan for fabric replacement when it is needed. In addition, it will go a long way with your insurance company, client and building officials if you can show that you have made an effort to be professional with the care of your fabric structures.
When it comes to permanent tension fabric structures, the common response to maintenance is “pay now, pay later, or have a plan.”