Modern snow guards are available in many shapes and sizes
Most snow guards hold snow on the roof until it melts, but some are designed to break it up as it comes off the roof. The most popular pad-style snow guards are made of polycarbonate or stainless steel. Pad-style snow guards are individual snow retention products usually installed in multiple staggered patterns going up the roof. The rows work together as a complete system to protect the roof from uneven loading and to prevent snow slides. A manufacturer’s layout should be obtained prior to installing any snow guard system.
Once installed, polycarbonate guards are practically invisible and do not detract from the building’s appearance. Clear snow guards enable the UV rays to transmit through the guard to assist in the curing of the adhesive and/or sealants.
They will never rot, rust or corrode and will usually outlast the life of the roof. They can be attached with glue or screws. Pointed guards can also be attached with 3M VHB Peel-n-Stick tape for light duty applications. Polycarbonate snow guards can be color matched if specified. Unfortunately, there are many different grades of polycarbonate used to make snow guards. Prices can fluctuate based on the grade of polycarbonate and where they are made. Reputable manufacturers use a UV-stabilized, virgin-grade, Lexan or equal quality of polycarbonate to ensure the product will last the life of the roof.
Depending on the panel being used, snow guards should be properly matched to be sure that the guards fit flush on the panel. Centering the guards in the pan will provide the most efficient holding strength and is most aesthetically pleasing. Matching the correct guard to the specific project is the first step in designing a quality snow guard system. Keep in mind, all snow guards do not fit all roof panels.
Adhesive mounting is considered by many experts to be the safest mounting solution to avoid panel damage. Generally, the worst that can happen, if overloaded, is the guard will release from the panel harmlessly. The snow guard can then be reattached in the same spot without adverse effects to the roof or guard.
Clear polycarbonate pad-style guards can be attached with Surebond SB-190 on just about every metal panel manufactured today, except round corrugated panels. Glue down snow guard systems are just as strong and effective as any other type of snow retention system if they are properly designed and installed using a professional
Pad-style guards can also be mechanically fastened with a non-corrosive #14 neoprene washered screw and silicone sealant. Screws must be driven into at least 1 1/2 inches of solid structural wood, a metal purlin, or at least 1 1/2 inches of wood blocking. It is important to note that metal panels alone will not hold the screws and the guard will eventually pull out, leaving holes that could be a catalyst for roof leaks.
According to independent Architectural Testing Inc.’s lab tests, screw down guards are able to hold 300 to 400 percent more snow load than adhesivemounted guards, so fewer rows may be necessary with this system design. Always remember that on longer roof slopes, multiple rows are important to distribute the snow load and stop the snow and ice movement before it begins.
3M VHB tape
Another type of adhesive attachment is 3M VHB, two-sided, acrylic, pressure sensitive tape used in conjunction with SB-190 to seal around the perimeter. While this type of attachment seems attractive and simple, it is considered a light-duty adhesive application, but is a viable option for colder weather installations.
This attachment method should only be used with a pointed snow guard designed to break up snow and ice. Snow guards with flat faces are designed to hold the snow load for longer periods. Therefore, they need they need a much stronger adhesive such as Surebond SB-190.
Brion McMullen is president and CEO of SnoBlox-SnoJax, Mechanicsburg, Pa. To learn more, go to