In colder climates, contractors and owners of buildings with metal roofs should consider the potential liability of a snow and ice avalanche after any winter storm. When the weather breaks and the sun emerges, it melts the ice on the surface of the roof panel. Water from the snow melt creates a lubricant which is the catalyst for snow and ice to slide. These dangerous avalanches could potentially cause injury or death to pedestrians, bend gutters, destroy automobiles, HVAC equipment, livestock and other property below.
With over 32 years experience supplying snow guards to the post frame industry, we have found that there are several important factors to consider when selecting the proper snow guard for metal roofing applications. The most important features to consider are the height, width and shape of a snow guard or rail system. This determines its ability to hold back layers of heavy ice and snow. A pad style guard should have a flat, forward mounted face that measures at least 3 inches across and stands no less than 2.5 inches high. It must be mounted in the lowest portion of the roofing panel where the snow and ice actually moves, not on a high seam above the problem area. Snow guards mounted on a high seam will cease to be effective once the snow and ice compacts on the panel and becomes lower than the guard. A bar or rail system should always have a flat face or square tube with an ice stopper, at least 3 inches wide, mounted perpendicular to the panel flat. Installing the correct type of ice stopping device is the key to keeping the snow and ice from going under and over the bar.
The two most common types of snow retention systems today are the pad style guards which mount in the panel flats and the rail systems which crimp to the seams. On standing seam floating panels, adhesive mounting is the preferred method of attachment for pad style snow guards. This mounting method does not restrict the natural thermal expansion and contraction process of floating metal roof panels and in the event of severe snow drifting conditions, it provides a release feature that eliminates the possibility of panel damage. The other method is a crimp on snow guard or rail system. It is very important to remember that crimp on guards or rails have no release aspect and panel damage could occur if snow loads exceed the design capabilities of the clamp. Therefore, these systems should always be installed in strict accordance with the manufacturers recommendations!
Another noteworthy consideration is the type of material from which the snow guard is made. Clear polycarbonate is virtually invisible and will not create corrosive galvanic reactions caused by dissimilar metals exposed to outdoor elements. Because all plastics do not maintain the same characteristics when exposed to various weather conditions, the consumer should only consider using a product made from a virgin grade, UV stabilized, prime polycarbonate material. Our company uses the same type of polycarbonate, approved by NASA, used to make astronaut face masks.
Something else to consider, clear pad style snow guards are far less noticeable on a roof than colored ones. A color matched snow guard will act as a sundial and cast a conspicuous shadow. Think about this scenario, a person is standing in front of a building and is looking up at the roof. What do they see? They observe all the protruding objects that do not blend with the sky, including nontransparent snow retention systems. Clear snow guards unify with the skyline and in most cases, are almost undetectable.
With so many snow retention choices on the market today, it may be difficult to choose the correct system for your roof because there is not just one type of snow retention system that is perfect for every application. Some types of metal roofing do not have the proper seam height and are not structurally suitable for use with a clamp down system. While it is usually harmless to the panel to use an adhesive mounted system, weather conditions may not always be ideal for immediate installation.
When it really comes down to it, choosing an experienced manufacturer and following their instructions and spacing recommendations is the key to a successful snow guard installation.