Snow-Guard Essentials
With the revived interest in traditional hard roofing materials, there has been a corresponding growth in the demand for snow guards. Here is a concise report on the purpose, history, and installation of these safety devices.
by Brian C. Stearns, Alpine SnowGuards
I have often been asked the fundamental question, "What is a snow guard?" And then of course there's the waterfall of questions that invariably follow, such as, "Why do I need them? How long have they been in use? Which type of snow-guard product is designed for which type of roof? How many do I need? How and when should I install them?" The list goes on and on.So as I set out to write this article about snow guards, I decided that a question-and-answer format would be the most reader-friendly. I should state at the outset that my knowledge of and approach to the snow-guard business derives from my experience in the slate-roofing industry, and so my perspective is that of a roofing contractor: The product must be practical, easily installed, and reliable. For more than a decade, my crew and I removed and dissected hundreds of snow guards, some of which were centuries old. Then came the challenge to learn about and improve upon this very old roofing accessory. Sitting here at my desk years later, I am happy to share with you my knowledge about that very old and fascinating product called a snow guard.
What Is A Snow Guard?A snow guard is a device that is mounted to a sloped roof surface to prevent a potentially damaging single release of snow and ice from that sloped roof (similar to an avalanche of snow on a mountainside). Snow or freezing rain accumulates on a sloped roof surface, and as heat from the building and/or exterior temperatures rise above freezing, a film of water develops between the roof surface and the snow and ice. This water functions like a lubricant, making the roof surface almost frictionless. Without a prevention device, the accumulated snow and ice can then slide off the roof surface in one big release, causing a great deal of damage: Cars get crushed, gutters and plumbing vents are often stripped from the roof, ground-mounted mechanical units are destroyed, roof surfaces below that higher roof get smashed, heavier blocks of ice crash through atrium windows or skylights, expensive landscaping is destroyed, and most important, people can be injured.
When
& Where Did The Snow Guard Originate?
Preventing snow and ice from sliding off sloped roofs is a centuries-old
problem. The first prevention system I know of originated in
Europe and consisted of a variety of rocks, spread randomly over
a relatively shallow pitched slate roof. Although the rocks did
create friction in the form of an obstruction, they were not
very effective. It was bad enough to get hit by sliding snow
and ice; the added worry that rocks might come sliding off in
the snow mass was not appealing. A second approach to a snow-guard
device was to attach wooden members to a roof, some of which
were logs suspended by chains from the roof's peak, to create
a continuous horizontal member or barricade device.
This idea was good in theory but the wood eventually rotted and gave way. Failures inherently occurred at the least-desirable time, when the roof was under a heavy snow load, and were therefore disastrous. By the early-19th century, roofers and contractors had figured out that metals were best suited for making snow-guard devices. The initial designs ranged from individual pad-style pieces that were placed in the roof in an array of patterns, to brackets that held wooden members or pipes to create a fence. The most popular style until the early 1900s was the wire-loop snow guard, which was small and inconspicuous. It was generally accepted that, when properly installed on the entire roof surface, the wire-loop snow guard was the most effective and desirable system.
From the Depression era of the 1930s until the early 1970s, the demand for steep-slope hard roofing materials and related accessories dwindled. By the '70s the price of oil-dependent roofing products such as asphalt had increased dramatically, and consumers began to look once again at hard roofing materials like slate, tile, and copper. These more-durable materials quickly became an affordable alternative, and as traditional roofing materials began to experience a revival, so did the accessory market for products such as snow guards. During this same period of the early 1970s, innovations in the metal-roofing industry were made using roll-forming equipment. With this new equipment, on-site installers could fabricate metal panels that were as long as the roof's rafters but didn't require horizontal joints. Because of these technological advancements, and the fact that metal became more cost-effective when compared to asphalt-related products, the use of metal as a roofing product began to take off.
Where Should I Buy
Snow Guards?
During the hard-roofing heyday (1870-1930), there were many companies
manufacturing snow guards. Multiple patents were also awarded
for snow-guard inventions during this period. Comparatively speaking,
few snow-guard manufacturers remain today. Some larger roofing
manufacturers include snow guards in their product line, but
they have difficulty explaining how to properly use and install
them -- which creates a problem for many of today's roofing contractors
who have never used or installed a snow guard. Thus, I advise
purchasing the product from a specialized manufacturer with a
support staff that's knowledgeable about snow-guard layout, use,
and installation. (See the Snow Guards SourceList in the July/August
2000 issue of TRADITIONAL BUILDING magazine for an overview of
suppliers.)
Snow-guard manufacturers produce a wide variety of devices, including the age-old wire-loop snow guard; the traditional three-pipe adjustable-style bracket; snow fences; a variety of metal pad-style snow guards; plastic glue-on pad-style snow guards; and snow-guard devices that attach to standing-seam metal roofs. Although I am naturally biased toward the snow-guard products produced by my company, Alpine SnowGuards, nearly all snow guards available in today's market will work effectively if used in the proper quantity. Ask the manufacturer for test data indicating how much weight or load their product can withstand. Educated consumers should question the data upon which the manufacturer's warranty is based. Remember that snow guards are intended to prevent bodily injury and are therefore of great concern to commercial- and industrial-building owners, especially from life-safety and liability perspectives. You will also benefit from working with a company that understands hard roofing and can troubleshoot any problems that may arise later.