In areas prone to heavy snowfall, building and roof designs should
consider how to handle this natural phenomenon. Several factors pour
into this process, such as site planning and landscaping, pedestrian and
vehicular traffic patterns, wall construction, foundation drainage, wall
design, eave and guttering, and roof design.
Experts on the topic say snow retention systems should also be
considered in the plan. "The concept that underlies the use of snow
retention systems is simple: It is better in some situations to retain
snow on the roof so that it evacuates gradually (by thaw), rather than
suddenly (by avalanche)," says Rob Haddock in his award-winning
technical paper, "Use of Snow Retention Devices - Science or Science
Fiction?" Haddock is head of the Metal Roof Advisory Group, and
technical advisor to metalmag. (Editor's note: the complete paper can be
viewed at www.metalmag.com.)
Matching the design to the need
Haddock emphasizes attention to detail for optimum snow retention. "Most
mistakes are a result of failure to design the snow guard system to the
specifics of the project. This can result with the snow guards failing
because the design loads exceed their capacity; or it can also result
with inadvertent gross over-design, which is a waste of money," he says.
Bob McHugh, head of Robert C. McHugh Architects, Paonia, Colo. agrees.
"Handling snow anywhere starts with the design of the structure. But
what works in one area may not in another because of local snow
conditions. In places like Steamboat Springs we have to hold back
thousands of pounds of snow, so the snow guard has to be stronger to
hold more snow."
Without snow guards, McHugh says, the situation becomes dangerous. "In
our area, a metal roof will probably hold snow through January. In
February, as it starts to warm up, maybe four feet of snow may zoom off
en masse if there is nothing to stop it. It also might start inching off
with a layer of ice on the bottom. When it slides,
the ice can damage the roof, rip things in its path and kill anyone
standing below it. At a certain pitch, maybe a 5:12 on a house, it will
curl off and break the windows under it," he adds. McHugh has designed
commercial, residential and institutional structures in the Western
Colorado area for more than 30 years. (www.robertcmchugh.com)
Haddock also points out misconceptions about the capability of snow
guards relative to icing. "While it is a myth that snow guards cause
eave icing, it is also a myth that they will cure any icing problems. On
occasion, snow guards are used as retrofit devices with the misguided
belief that somehow they will alleviate or mitigate icing problems. They
Fitting your project's needs
The market has many snow retention devices for metal roofs. While
manufacturers can provide spacing recommendations and cite holding
strengths, Haddock emphasizes the importance of evaluating each project
for specific needs. "The frequency and placement of snow guards should
be engineered to resist the forces to which they will be exposed in
service. Those specifics vary from job to job, as they are affected by
slope, roof length, local snow loads, and other factors. But really, it
all comes down to a simple matter of mathematics."
Although snow guards vary widely in color, size and design, two basic
styles exist: single units and fence systems. They are made from plastic
or metal, and can employ a variety of methods to blend with the roof on
which they are used, including color-or the absence of
color.Installation is accomplished through different methods, including
adhesives, screws, clamps, and soldering.
To help start your research, we offer this sampling of products based on
supplier information as well as a complete list of snow guard
SnoBlox products are made by the
creators of Snojax. Each is a separate company, but both SnoBlox and
Snojax products are manufactured using clear UVstabilized polycarbonate
Snojax was patented in 1978, which the manufacturer says makes it the
original plastic snow guard. Both companies are exclusive to the snow
guard business and do not manufacture or market products not related to
SnoBlox single unit-style models are designed to offer high quality at a
reasonable price. SnoBlox offers two sizes of patented snow guards to
fit most roof panels: the larger ACE model will fit more common panels
while the DUECE model is capable of fitting panels with narrower roof
spaces. A waffled base is designed for maximum adhesion.
The manufacturer indicates that SnoBlox products can be used on any
glossy coated metal roof. SnowBlox also features a new product called
Ventsaver designed to protect roof vents, chimneys and masts, and to
eliminate the need for crickets. Ventsaver may be used on roofs with or
without snow guards. SNOJAX Products
Snojax products are single unitstyle models. The original model, Snojax
I, is for use in screw-down applications only. Snojax II offers the same
qualities as Snojax I, with the option of adhesive application. The
single units are available in two sizes, both of which can be mounted
either with adhesives or screws. The manufacturer indicates that Snojax
products can be used on any glossy coated metal roof. The company also
offers adhesive products, which are posted on its Web site.
Installation and use
The manufacturers of both Snojax and SnoBlox products emphasize that the
placement of snow guards on a roof is crucial, and each offers tools on
its Web site to help determine the number and spacing of guards. They
also note that if adhesives are used, proper temperatures and curing
times must be observed. SNOBAR Products
SNOBAR is a snow Retention system in the fence system style: a stainless
steel or galvanized bar that spans a portion of a roof, and is attached
to the roof's standing seams using a stainless steel clamp. No
penetrating screws or adhesives are required for installation. According
to the manufacturer, the SNOBAR can be curved to fit tapered roofs, and
is offered in either mill-finished stainless steel or can be factory
painted to match the metal roof panel.
A new product introduced at METALCON 2002 in October is the SNOBAR
system that uses a U bracket. This variation on the original SNOBAR is
for use on corrugated panels, primarily those with exposed fasteners. .
A screw-down, stainless steel U bracket holds the bar in place with a
tek screw. As with the original SNOBAR, both brackets and bars can be
painted to match the roof panels.
Ice stoppers are available for both SNOBAR systems; this optional
equipment hangs from the bar to help keep snow and ice from sliding
underneath the bar. Ice stoppers come in aluminum or stainless steel,
and can be painted to match the roof material.
Installation and use
SNOBAR encourages the use of snow guards to protect not only gutters and
roof stacks, but also any possible pedestrian traffic, expensive
landscaping, and HVAC equipment. When it comes to installation, the
manufacturer says it always checks to make sure the building is properly
designed by examining ground snow load, roof slope, and panel widths and
lengths. Clamps should be set properly on seams, and manufacturer
instructions for clamps and set screws must be carefully followed.
SNOGEM offers a total of four different single unitstyle snow
guards, two made from polycarbonate materials, and two made from metal
forms. The Original SNO-GEM and SNOGEM, Jr. are both created in the
shape of a crystal. The SNO-GEM, Jr. is half the size of the Original
SNO-GEM. According to the manufacturer, virgin-grade, UVstabilized
polycarbonate materials are used-and by using a mold injection process,
color can be added for a uniform match to any roofing material. The
polycarbonate models can be applied to the roof using one of three
methods: tube adhesive; 3M pre-applied peel-andstick tape; or mechanical
The company has a new entry, the Original Metal SNO-GEM offered in a
smaller size and known as the Half-Carat SNO-GEM. The guards are made
with metal forms and can be created from a choice of metals to match the
roofing material, says the manufacturer. The Original Metal SNO-GEM and
Half-Carat SNO-GEM can be installed using the same three methods as the
company's polycarbonate models. In addition, the company offers a method
for soldering copper units.
Installation and use
SNO-GEM says its snow guards should be specified according to the roof
panel profile, and that its products can be adopted to fit a variety of
panels. The manufacturer emphasizes that no steps in the installation
process should be ignored. Start with cleaning the roof, and finish with
sealing the entire perimeter of the guard. Layout is also important, and
adhesive application should be done only in proper temperatures and a
Berger Bros. manufactures Real- Tool, a
commercial line of snow guard products that includes five models in both
the single-unit style and the fence style. Guards are offered in copper,
stainless steel, bronze, galvanized iron, clear polycarbonate, and in a
variety of stamped patterns and ornamental castings.
For standing seam metal roofs, Berger Bros. offers two series of
single-unit style models: RT and AP. According to the manufacturer, both
models are fastened to the seams without penetrating the roof surface.
The RT and AP series are offered in mill finish, black primer, or a
custom color; the RT models also are available in bronze.
The SM and CL series (also single-unit style) are designed for flat
areas of metal roofs, and are applied using adhesives. Models in the SM
and CL series are available in mill finish, black primer, custom color,
and clear polycarbonate, depending on the application. The company also
offers adhesives on its Web site.
Also from Berger Bros. is the FRail, a fence style snow guard that is
affixed to standing seams. The FRail system uses a bar that sits below
the standing seams, which the manufacturer says is designed to eliminate
any space between the bar and roof surface. The company also offers a
full line of snow guards for residential applications.
Installation and use
Berger Bros. recommends using a professional roofing contractor, instead
of the building owner attempting installation. The company also urges
careful use of adhesives, in only the proper weather and temperature
S-5! Metal Roof Innovations originated
mechanical, nonpenetrating attachment technology for standing seam
rooftop accessories. S-5! Utility clamps grip the panel seam without
piercing by using round-point setscrews to ensure a positive engagement
without damage to the panel material or violation of roof system
warranties. Holding strengths of the S-5! are lab tested and published
on the company's website.
S-5! offers three snow retention systems: ColorGard, SnoFence, and
SnoRail. All use continuous crossmembers and are metalurgically
compatible with any metal roof type, and available for any seam profile.
ColorGard is attached to standing seam profiles with S-5! clamps, and to
face-fastened metal and other roof types with the VersaBracket.
ColorGard utilizes the same factory finished material as the roof for a
perfect color match.
SnoRail and SnoFence are cylindrical in shape and come in mill finishes
of stainless, brass or aluminum. For attachment to facefastened panel
systems, the manufacturer recommends the VersaBracket with pre-applied
sealant in the base for flawless waterproofing of the attachment.
Installation and use
S-5! snow retention systems can be installed in any climate at any time
of the year with tools that are common to the trade. Each system is
custom engineered to the specifics of each project, and sitespecific
design and layout is available from independent distributors nationwide
or through the S-5! website. Tested holding strengths are guaranteed by
the manufacturer not to degrade with time and exposure.
I'm so glad I live in Florida and don't have to deal with this...
The last time we had to deal with snowfall in Florida was back in the early 70's!
New SNOWGRIP Coating is great option.. See at www.snowgripit.com
What about SNOWGRIP...It's by far the best retention system available,,,and does so much more. Check it out at www.snowgripit.com stopping snow on the eve of a roof is not good for the roof and creates uneven, unsafe, ice and snow loades...Hope you can take a good look at this product and even advise your readers to the only system that will never allow a release of snow...only water runs off,,,creating an effective insulator while lessening the snow load w/o compounding it...
By Paul Blomquist