A standing-seam roof provides long-term performance. Its snap-together and field-seamed versions are engineered for strength, durability and weather-ability. The accompanying photos show 3-inch trapezoidal systems that have weathered unfriendly environments for more than 25 years. With virtually no wear, their maintenance costs are nominal.
Standing-seam roofs are typically made of 24- or 26-gauge steel manufactured from high-strength Galvalume, a special type of hot-dip galvanized steel sheet with a coating of 55 percent aluminum, 43.4 percent zinc and 1.6 percent silicon. These roofs are produced to ASTM A792/A792MAZ50 or AZ55, and their seams feature factory-applied mastic to ensure a water-tight seal.
A majority of self-storage buildings are made with steel columns and roof purlins on very low slopes. When using a concealed-fastener roof system, the panels snap or are seamed together over a sliding clip fastened to the purlins below. To provide maximum efficiency, the floating clip can only be installed when the tab is centered in the clip base.
The advantage to roof panels that interlock over floating clips is they have the ability to expand and contract as the temperature changes, instead of pushing and pulling at the fasteners as in a screw-down roof system. Because the standing-seam roof “floats,” it has a longer lifespan. In addition, with no exposed fasteners inside the building envelope, there’s no way for water to penetrate.
On structures other than standard storage buildings, such as a manager’s residence, office or canopies, a steeper slope is often used to provide a more appealing look. This opens the door to several roof-panel options. On a steeper slope, a vertical seam panel is the ideal choice. It offers simple installation, and the trim work is efficient, maintaining the integrity of the overall system.
As the self-storage industry has matured, the architectural designs required by planning boards and development covenants have become more sophisticated. First-generation styles are giving way to multistory buildings and structures with features such as glass corners and brick or stucco exteriors. The accompanying photo shows what can be done with a standing-seam roof system. With coordination between client, architect and manufacturer, almost any design can be accomplished.
When it comes to roofing, almost any properly installed system will work well for the first year, but what happens as the facility ages? Unlike flat built-up roofs that require frequent maintenance, a standing-seam roof will offer 20 years and more of trouble-free performance with little or no time or expense. There’s no need to constantly replace fasteners or caulk penetrations. The only necessary maintenance is to keep the roof clear of debris.
In addition to saving money on maintenance fees, a standing-seam roof minimizes energy costs. Because it’s installed over an adjustable clip, it doesn’t crush the insulation, helping preserve the insulation’s R value and keeping HVAC costs to a minimum.
The permitting process can never be taken for granted. The last thing you want to hear before your permit gets signed is your building doesn’t meet all the codes and specifications for your area. Standing-seam roofs have been designed for high-profile projects in any location. For example, the 3-inch trapezoidal panel has been approved by Under-writers Laboratories, Dade County, Fla., Factory Mutual, Corp of Engineers, ICBO (International Conference of Building Officials) and ASTM (American Society for Testing and Materials).
A 20-year materials warranty is customary for a standing-seam roof system, considerably longer than the standard protection for builtup and single-ply roofs. Long-term warranties are even offered for weather-tightness on standing-seam roofs, including those with a 1/4:12 slope. Most reputable manufacturers won’t offer such a warranty for a screw-down system, as it will almost always leak, no matter how well it is installed.
When choosing a roof installer, you can use one certified for your specific product. Although the systems appear to be similar from vendor to vendor, each has a particular design. A certified installer will have attended the manufacturer’s school and installed a certain number of square feet of the product. In addition to certification, ask for documentation of the installer’s license and insurance.
The self-storage market demands an attractive, trouble-free, durable roof product. Available in many styles and colors, a standing-seam roofing system meets that need and is here to stay. When designing your facility, consider the investment being made and use the best materials on the market.
Stephen Wilson is the Southeast regional sales manager for Miller Building Systems Inc., which designs, supplies and installs a full line of pre-engineered metal buildings, including single- and multistory, climate-controlled self-storage, modular buildings and rigid-frame structures. Wilson has 25 years of experience in the manufacturing and sales of pre-engineered steel buildings. For more information, call 888.323.6464; e-mail firstname.lastname@example.org; visit www.millerbldgs.com.