Top Seam Clamp Recommendation: Understand Testing
Colorado Springs, Colo., March 4, 2016 – As the metal roofing industry works to grab a larger share of the roofing market, for both re-roofing and new construction, so grows the idea of attaching ancillary items to those standing seam metal roofing systems. Everything from snow retention systems to solar panels are being connected to those seams.
Installers should be selective about the metal roofing systems they install. They should learn as much as possible about the quality of the substrate, the coating and the panel anchorage, as well as the warranties offered by the manufacturer. Metal roofing manufacturers invest in the third-party testing of their systems, tests for wind uplift, wind driven rain, water and air infiltration, debris, impact resistance and even fire resistance.
Similar cautions should be observed when selecting a seam clamp for the attachment of any ancillary item on a standing seam metal roofing system. It should be serviceable for the life of the roof. That may not sound like a big deal, but consider the different number of panel profiles and seam styles available on the market today. Then consider how many manufacturers are offering those goods, because every profile produced by one manufacturer is a little different compared to that same profile produced by another manufacturer when it comes to the exact seam geometry.
That’s why testing becomes so expensive: There are about 20 different snap-lock profiles being manufactured and as many trapezoidal standing seams, and a growing list of “T” seams, bulb seams and nail flange profiles. Many are offered in multiple gauges and materials (steel, aluminum, zinc, copper, stainless). Here at S-5!, we have spent the money to test our seam clamps for holding strength on every standing seam system in the industry in order to host load-critical ancillary items. In fact, we test each roofing profile three times, averaging the results. Any variance in the foregoing variables will affect the holding strength. We test seam clamps in two different load directions with setscrew tension installed to 115 inch-pounds, but publish and instruct an installation tolerance of 130-150 inch-pounds to ensure the minimum tested tension is, in fact, reached. Then we use a minimum safety factor of 2.0. This enables the safe and prudent design of any ancillary attachment to distribute specific forces of nature into the metal panels and structure with confidence that it will perform without risk in service.
We also provide web-based tools to enable the users of our systems to properly design roof accessory applications so that they will perform for the life of the roof without failure. Absent the panel-specific testing, there is simply no way to quantify holding strength and design such an engineered application. A good example is snow retention. Snow on a roof presents specific loads on the snow retention system. These loads can be easily calculated, and with proper testing the snow retention system can be designed to resist them successfully.
Currently there are no ASTM or UL tests for the holding strength of seam clamps and any possibility of standardized testing is still years away. For that reason we invented a protocol for appropriate testing and have performed thousands of tests in a third-party A2LA accredited lab over the last 23 years.
Seam clamps are manufactured with different screw points where they engage the standing seam. Availabilities include common cup-point setscrews and the highly recommended oval- (or “round-”) point setscrews.
A cup-point setscrew features a concave indentation on the screw tip. This screw is mainly used in applications where the cutting in of the cup-point end of the screw is desirable, such as securing a pulley to a shaft. Oval-point setscrews feature a rounded point on the screw tip. This setscrew is used in an environment where minimal deformation or damage to the substrate is required.
The Metal Building Manufacturers Association (MBMA) writes in its Metal Roofing Systems Design Manual, “Any attendant setscrews that secure the clamp to the seam should have a rounded point (not a cup-point) so that gouging or breaching of the metallic coating is avoided,” In addition, the Metal Construction Association (MCA) reports in Metal Roof Design for Cold Climates, “Some mechanical attachment products utilize “cup-point” setscrews that may tear the seam material under load or damage panel coatings leading to premature corrosion. Other clamping products use round tipped setscrews to avoid this panel damage. Some use only one setscrew, others use several. Again, appropriateness and completeness of lab testing should be scrutinized as well as the specific details of attachment before a final system choice is made.”
MCA has another document on its site, under Resources: Technical Resources: Other: Special Note A: Use of Seam Clamps and Brackets. It reads, “Stainless setscrews or other nodes that engage the cladding material, should have rounded tips so as not to abrade metallic coatings on steel, or cause fracture points to other metals listed. Sharp edges or points on fasteners or clamps engaging the seam should be avoided.”
A standing seam metal roofing system, including those with ancillary products fastened to their seams, is only as good as its weakest link. The weak link won’t be the seam clamps, if you educate yourself about the testing methods and results of the specific seam clamps you install. You can’t put a price on safety. Do it “the right way”!
S-5! zero-penetration clamps attach ancillary items to standing seam metal roofs without violating the integrity of the roof or the roof’s warranties. The clamps mount snow-retention and wind-performance systems, solar arrays, signs/banners, light fixtures, gas piping, stack/flue bracing, walkways, HVAC, lightning protection, equipment screens, conduit, condensate lines and more.