Proof of engineering
Project-specific engineering should be provided by the vendor. It must incorporate the tested ultimate strength of the system with the application of an appropriate factor of safety. It is important to review the calculations prior to product selection. Ideally, the vendor should offer a web-based calculator with real-time output showing calculations and allowable loads specific to a project.
At a minimum, require these calculations with submittals. It is also recommended to specify they are stamped by a registered professional engineer.
Proof of certified manufacturing
How can you know if the product tested is truly the one you purchased? Systems may look the same, but alloys, tensile strength, yield, and other mechanical properties should be verified through certified manufacturing with third-party audits in a facility compliant with ISO 9001-15, Quality management systems — Requirements.
Warranties
Does the manufacturer offer a meaningful performance (not just material) warranty? Obtain a copy prior to specification, and it is advisable to read the fine print. Will they be in business for the long-term to honor the warranty, if it is needed? Has the vendor substantiated its track record? How long the company has been in business is irrelevant. The question is, “How long and on how many projects has the system in question been proven effective?”
Further
It is important to enforce the specification. A lack of code mandates enables a free pass to unqualified systems and potential designer liability. Require the vendor to provide a written statement of compliance with MCA’s guidelines (details at MCA’s technical bulleting on “Qualifying Snow Retention Systems for Metal Roofing”).
Conclusion
Metal roofs are known for their durability, sustainability, and versatility. However, they are slippery and can cause rooftop avalanches in the discharge areas below the eaves, thus resulting in property damage and personal injury or even death.
A scientifically tested and engineered snow retention system mechanically resists sliding snow, so the buildup of snow and ice on a roof evacuates in a predictable and controlled fashion rather than by a sudden release of snow.
To determine the best snow guard system for a metal (or other slippery) roof, one should understand the art and science behind snow retention systems, and most importantly, vet the manufacturer and their product offerings.
A smart and rather low-cost investment in a snow retention system specific to the project’s metal roof profile not only protects the roof and roof elements, but also the rest of the building and its occupants, pedestrians, vehicles, equipment, and landscaping below. It reduces short- and long-term maintenance costs, and, mostly, reduces potential liability for building owners and designers.
Rob Haddock, the inventor of S-5! attachment technology, is a former contractor, an award-winning roof-forensics expert, author, lecturer, and building envelope scientist. Haddock was awarded the CSI 2018 Ben John Small award, and has worked in various aspects of metal roofing for nearly five decades.
