By Derek Gamble, SnoBlox-SnoJax
Today’s snow guard options are numerous. Some customers choose guards that are meant to keep snow and ice on their roofs. This method allows the snow and ice to melt in place. Other guards have the ability to break shedding snow and ice into safe and manageable pieces. Universal fit models are very popular, while some companies also offer panel specific solutions. These individual guards are referred to as “pad style snow guards” These are the oldest and most popular style of snow guards. Individual Seam mounted snow guards, while still popular, are notorious for allowing snow and ice to flow around them. With a pad style guard, the protection is in the center of the panel where the action is.
Prior to 1976, snow guards were exclusively made from metal. This allowed for corrosion issues due to dissimilar metals reacting when exposed to outdoor conditions. This problem ushered in the invention of polycarbonate snow guards, which revolutionized the snow guard industry. These clear snow guards offer the benefits of UV stabilization, corrosion resistance, and practically invisible aesthetics when installed. Many companies offer these guards and as such, many different grades of polycarbonate are used, causing prices to vary greatly between manufacturers. Lower-end products often lure unsuspecting customers in with cheaper pricing. Unfortunately, the low pricing is achievable for these companies due to a lack of testing, which leads to unpredictable performance. Customers should make sure to do their research when selecting a product for their home’s roof.
If metal is more your style, then stainless steel is what you need. Unlike cast aluminum, which becomes brittle over time, stainless guards are the strongest option in the metal pad-style category. Decorative designs and custom powder-coating options make stainless guards very popular among those with historic homes. Independent lab testing has proven, however, that metal guards are not as strong as their polycarbonate competition. Metal guards tend to bend when overloaded, while polycarbonate guards are semi-flexible and can continue to maintain their shape even under overloading conditions.
Polycarbonate guard detractors often advertise that these guards are weak and prone to failure. The truth is that most failures with these models are caused by improper installation. A manufacturer-provided layout is critical to ensuring that snow guards will function properly. A spacing layout should be requested during the project’s planning phase, allowing an architect to include proper information in the project’s specifications. Specs without proper layout information are a huge liability concern. The biggest mistake that is made involves installation of these guards in straight lines, as opposed to the recommended staggered formation. Staggering creates a field where the weight of snow and ice can be equally distributed over a larger area. It is also crucial to purchase your guards from a manufacturer with professional laboratory strength testing. Without testing, there is no way to determine if the guard being considered for the project will be appropriate for a specification with a load-based safety factor.
Pad-style snow guards have various methods of installation depending on model. It is vital to a snow guard’s performance to install them using the manufacturer’s recommended method of attachment based on your roof panel. Most polycarbonate guards are easily installed with the use of a high-grade adhesive. This is considered by many experts to be the safest mounting solution to avoid panel damage. This is recommended for standing seam panels, where penetration is not an option. Adhesive mounting typically comes with an extended curing period that should be considered when determining the best time for installation. While this method can be used on almost every metal panel available, it is not recommended for use with round corrugated panels, EPDM-style membranes and slate- or shingle-style panels.
For those customers with exposed fastener metal roofing, mechanical attachment of snow guards is a popular method of installation. According to independent ATI lab tests, screw down guards are able to hold 300%-400% more snow load than adhesive mounted guards, so fewer rows may be necessary with this system design. While this type of attachment is as old as metal roofing itself, there are a few things to consider. First, screws must be driven into at least 2” of solid structural wood, a metal purlin or at least 2” of wood blocking. The metal panels alone will not hold onto the screws and the guard will eventually pull out, leaving holes that could be a catalyst for roof leaks. Use of an exterior grade, all-weather, neutral curing sealant that can be applied at low temperatures is a necessity. Without it, water is allowed to form under the guard potentially freezing and disengaging the guards from the roof.
For customers with slate, asphalt shingle, and composite shingle roofing, adhesive mounting is not effective and mechanical attachment can prove challenging if not impossible. Manufacturers have created a solution for this conundrum with specifically designed metal brackets and/or straps. These mounts can be installed with screws or nails while the roof is being installed. Some manufacturers also offer retro-fit solutions that mount to existing hardware without removal of existing roofing material.
Our last method of attachment utilizes 3M VHB Tape. This type of attachment seems attractive to many installers and customers due to the ease of installation. It is, however, considered “light duty” and is recommended for guards that do not hold snow and ice on a roof. Pointed-style guards that break snow and ice into smaller pieces, prior to shedding, are able to be installed with tape, as they do not support the load for long periods of time. Guards that allow for safe shedding are often used in situations when an area’s winter weather conditions often exceed the roof snow load design.