Winter Weather Protection: How to Prevent Dangerous Rooftop Avalanches From Happening at Home

With cold snaps, freezing and sub-zero temperatures hitting much of the U.S. and Canada, warmer springtime weather feels very far away indeed.

The Metal Roofing Alliance (MRA) cautions that in areas that experience heavy snow accumulation, taking steps to prevent rooftop avalanches–which have the potential to release thousands of pounds of snow accumulation in a split second–can help safeguard people and property during severe winter weather.

Understanding how different metal roofs perform under heavy snow and ice accumulation is the first step to avoiding a potential accident or tragedy. Finishes such as stone-coated metal roofs have a rougher surface texture which works to reduce the danger of rooftop “avalanching” by preventing snow from releasing in large, heavy and damaging sheets. Smooth metal roofing panels, whether painted or left unfinished, have much slicker surfaces and therefore, may require the use of quality snow guards. Snow guards are designed to hold back rooftop snow and allow it to melt more gradually and predictably to help prevent accidents.

While snow guards may seem like a simple concept, a well-designed system is based on math and science--not guesswork. If basic engineering principles are not followed, snow retention systems can be rendered ineffective–an accident waiting to happen. That’s why, when installing and designing an effective snow guard rooftop system, homeowners and their installers/snow guard designers should:
  • Understand local snow loads: Contact your local building officials to get information on the ground snow loads in your area. A roof’s potential snow load can be calculated from the ground snow load information.
  • Evaluate your roof’s characteristics: Your roof’s profile, material, slope, width of your panels, the rafter length (eave to ridge) and length of eaves help determine where your snow guards will be placed. Resources from industry leaders such as S-5! can help you determine what the profile of your roof is, if you don’t know. The company also offers a handy, easy-to-use Snow Guard Calculator available online. Additionally, S-5! offers the option to have the final computations stamped by a professional engineer and recognized for use in any of the 50 states.
  • Approach placement with care: Snow guard placement should be well thought-out and prescribed by an experienced system designer or installer. To properly place snow retention systems, a clear understanding of roof geometries, how snow accumulates and how snow behaves on a metal roof is necessary. As a general guideline, the entire eave line of a building should be protected, rather than focusing on an isolated area of the roof. For safety’s sake, avoid shortcuts such as placing snow guards only above doorways, which can make snow load shedding even more unpredictable.
  • Choose products you can count on: Primary snow guard system components should be fabricated from noncorrosive metals and have a life expectancy at least equivalent to the roof itself. Beware of any non-mechanically fastened, plastic or “stick-on” products: none of these options have the proven ability to remain in service for the typical expected roof service life. Choose only products that offer proper testing verification and warranted protection for the life of the roof.

Homeowners also need to be aware that even with the potential of danger, there are currently no building or governmental codes, standards or requirements for the proper installation and use of snow guards. That means, ensuring your installer or roofing professional is using quality products from reputable manufacturers and following best practices set out by organizations such as the Metal Construction Association (MCA) is important. Download MCA’s “Qualifying Snow Retention Systems For Metal Roofing”, free at

“No matter what the finish, quality metal roofs perform extremely well and are strong enough to stand up to heavy snow and ice. Be sure to select either a stone coated finish that offers inherent protection against rooftop avalanches, or install a reliable, well-designed snow guard system for smooth finish metal roofs. Either can provide peace of mind and protect your home and family during severe winter weather for many years to come,” said Renee Ramey, MRA Executive Director.