Snow guards for metal roofs canada how to#
How to Choose the Best Snow Retention System for Your Project Replacement time is often relatively soon after installation, depending on orientation to the sun and other environmental factors. Adhesives all diminish in holding strength, beginning with the first day of exposure. Moreover, the replacement costs over the life of the roof are extensive when, not “if,” the adhesive diminishes in holding strength. At a glance, stick-on snow guard systems appear to be a very convenient and low-cost option, but they are only lower in cost when you consider part costs versus total project costs (including labor and quantities required to do the job). Some variations employ a factory-applied adhesive, while others use a field-applied one. Using a Stick-On Guard: The third type of snow retention is a stick-on (adhered) part (a chemical attachment). Mechanical bracket attachment (for face-fastened roofs only) can also work successfully when tested and engineered correctly. This style also relies upon the shear strength within a snowbank to “bridge” between the individual units.īoth styles of snow guards (fence and cleat) have demonstrated satisfactory performance when tested, engineered, and installed properly and adequately. The other design consists of small, discontinuous individual units used as “cleats,” generally spot-located at or near the eave or repeated in a pattern progressing up the slope of the roof, again with a greater concentration near the eaves.
Depending on specific job conditions and load-to-failure characteristics of the devices, they may also be repeated in parallel rows up the slope of the roof, but with greater concentration near the eave area. One utilizes continuous horizontal components, assembled laterally across the roof in the style of a “fence.” Such assemblies are usually installed at or near the eaves. System Design: Two snow guard system designs are quite common. Snow guards rely on compressive strength of the snowbank (greatest at snow-roof interface and lower end of the roof).
The interface of snow retention devices at this location has proven to be strongly preferred worldwide and considered to be most effective. Gravitational forces compress the snowbank mostly at its interface with the roof surface, especially toward its lower (eave) end-so this is where compressive strength is greatest. All snow guards rely on the snow’s own compressive strength to restrain its movement. Snow Retention Population and Placement: Snowbanks typically accumulate and densify in a cross-sectional wedge pattern. Snow Retention System Design Considerations These three factors determine the vector force that a system must resist for any roof surface and should be included in plans and specifications requiring an engineered system. The service loads applied to a snow guard system are a relatively simple calculation, varying with site specifics, all of which should be known to the design team: 1. The forces of snow on your rooftop can be mathematically calculated, and should be for any snow guard system. Vector (PSF) = Vertical (PSF) x Sine of Roof Angle Vector (Pounds per Panel) = Vector (PSF) x Roof Length (Ft) x Panel Width (Ft) Understanding the Math & Science System testing must prove strength of system exceeds this calculated force. This calculation should be done for any snow retention system.
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