How Are Snow Guards Installed?
Snow guards can be installed on any sloped roof surface. Whenever possible they should be mechanically fastened directly to the roof deck. This attachment is relatively easy on a new roof installation, where shingles are being installed. There are a variety of products available that are designed to be installed between the shingle courses. When a pad-style snow guard is specified, the typical design is a long sheetmetal strap designed to be mechanically fastened to the roof deck above the head of the shingle. Some pad-style snow guards are designed to be hooked over the head of the shingle itself, or onto the shaft of a nail that is holding the shingle. This approach is the least desirable because these hook attachments have a tendency to pull out and/or damage the shingles as they fail. When a pipe-style snow guard is specified for a shingle roof, the base of the snow-guard bracket is usually sized to replace a shingle -- a common approach to a pipe-style snow guard for a slate, tile, or cedar-shingle roof. If a pipe-style snow guard is desired in a composition-shingle roof, the base pad is generally sized so that it can be installed in the same fashion as the strap on a pad-style snow guard. It's far more difficult to mechanically fasten a snow guard to a standing-seam metal roof or single-ply membrane roof without sacrificing the warranty on the roof.

	Several manufacturers have chosen to approach the metal and membrane applications with individual pad-style snow guards that are glued or adhered to the roofing material. Although a common practice, it is the least-desirable attachment method. In our experience, sometimes the adhesives work and sometimes they don't. Unfortunately, when snow guards fail, it's when they are loaded with snow and ice and are dangerous. In my opinion, adhesive-mounted snow guards provide a false sense of security and should be viewed as an inexpensive and temporary snow-retention solution.
Click here to view a larger version of the Membrane Roof Snowguard System shown above	One company has developed and patented a membranous roof attachment that accommodates mechanical fastening. In my opinion, the mechanical fastening method for membrane roofing is the best, most reliable approach. Certain manufacturers make snow guards for standing-seam metal roofs, which attach to the seam with locking mechanisms that essentially pinch the seam. These seam-clamping devices accommodate both pad- and pipe-style units and are generally effective when used in sufficient quantity and installed properly.
Click here to view more installation examples	The Candler Building, a landmark structure in New York City, was recently reroofed. The designers chose a membrane roofing product designed to mimic standing-seam metal roofing and provide a historic appearance. However, the roof was approximately a 12/12 pitch. The designers became very concerned about snow and ice dumping to the ground in such a highly populated area, and they realized the need to install a snow-guard system that would function well and look historic.

The most common and best functioning historic snow-guard system in the Northeastern United States is the multiple-pipe system. However, it created two problems: (1) How to install a snow guard in a membrane roof without creating a leak; (2) How to provide a continuous pipe-style snow guard with the ability to raise the lowest pipe hole high enough to clear the standing seam (approximately 1-1/2 in.). After evaluating the project requirements, the designers ended up choosing Alpine SnowGuards' #15 membranous-roof snow-guard system. We were able to adjust the height of the lowest pipe hole in each bracket to meet the project needs. The drawings accompanying this article cover just a few of the typical situations involved with the installation of snow guards.

When Should Snow Guards Be Installed?
The best time for snow-guard installation is during roof installation, when the roof deck is the most accessible. It's not uncommon for snow guards to be cut from projects due to budget constraints, but after one winter passes and snow and ice has caused damage or injury, building owners will look to retrofit their properties with snow guards. Depending upon the type of roof and style of snow guard desired, it can generally be done. However, in many cases the job requires opening the roof, disturbing work in place, and repairing the displaced work. Although this procedure is common, it should be avoided if possible. If I have failed to raise and answer any other questions that you may have regarding snow guards, or if I can provide you with more information about snow guards, feel free to contact me at Alpine SnowGuards, 888-766-4273, or e-mail me at brian@alpinesnowguards.com.

Brian Stearns is president of Alpine Snowguards, Stowe, Vt., and has spent most of his professional life working with slate and other traditional roof types. From his career as a roofing contractor, it was a logical transition to his company's current specialization in snow guards.