Summer always goes by quickly. Soon enough the kids will be back in school, the fall months will pass and we’ll be faced with winter weather. Anticipating a change in seasons, we should think about how to equip our homes and buildings for upcoming snowstorms. However, these structures shouldn’t be equipped with just any snow defenses. They should be equipped with the proper snow defenses. One of those necessary defenses is a snow retention system.

A snow retention system is a combination of devices installed on your roof that prevents snow and ice from sliding off of rooftops onto people and property below. Some buildings have plastic snow retention systems but imagine snow avalanching off of a rooftop, and the only thing holding the snow and ice back is plastic. Plastic isn’t a durable and dependable so that’s why we recommend having metal snow retention. We highly recommend metal snow retention systems and here’s why.

Metal can withstand excessive exposure to UV rays

Because of its tough nature, metal can withstand the sun’s destructive UV rays. Over time plastic will crack and deteriorate when continuously exposed to the sun.

Snow retention using metal snow guards are more secure

Unlike metal, plastic snow guards are attached to a roof using caulking, which is likely to fail for the following reasons:

• The roof is dirty or wet when installing (when have you ever seen a truly clean roof?)
• The snow guards are installed at temperatures below 40 degrees
• Caulking cure time is less than 30 days above 40 degrees. 

Metal is made to last

Plastic snow retention manufacturers generally do not warrant a failure to the entire snow retention systems, only the attachment. If a plastic snow guard fails, the architect or contractor becomes liable for the damage.

We recommend only metal snow retention because we know it can properly protect those in and around your home. For extra protection we engineer from the sheathing up with the fastener and provide a warranty on the entire snow retention system. Before installation, we engineer a specific layout to see that the system is exactly what you need for your specific location and weather. Contact us with any of your project details and we’ll provide you with the best snow defense system that’ll get you ready for winter.

There are typically three different types of methods used when installing snow retention on a metal roof.

• Fastening through the panel to the roof deck or structure.
• Fastening to the panel, by mounting or clamping to the rib.
• Gluing or adhering to the metal panel.

Each method has its pros and cons, so when should each method be used? This question is usually left up to the roofing contractor or architect.

Roofing contractors should know that many snow retention manufacturers offer warranties with their products if installed to specifications.  Ice damming and snow and ice movement are two of the most common roofing problems in snow areas. Snow retention manufacturers have experience calculating loads and recommending proper layout and design for snow retention devices. Consulting with a snow retention manufacturer can save roofing contractors money, liability and ensure a high quality snow retention device that has a low risk of failure. Even snow retention manufacturers can have occasional failures due to the many variables when retaining snow on a roof, so the little extra money thatis spent for a warranted product is well worth the cost.

The first method of attachment is to fasten the device to the deck or into the roofing struc-ture with lag bolts, anchors, welds, etc. This method provides great strength to the product transferring the loads to the structure itself.  When installing large, bulky snow fences this is the only way to go; it is the only way to provide enough strength to the large load that will be placed at the fence. Unfortunately fastening to the deck or structure forces us to punch holes through the metal panel, this increases the potential for leaks and forces the contractor to seal or flash the holes in some way. Also, installing fasteners through the panel prevents expansion and contraction and can cause tearing, buckling or other forms of distortion to the panel. Many panel manufacturers will not allow their product to be fastened in this way.

The second method of attachment is to fasten to the raised rib by clamping or pinching.  This method also can provide great strength, and also does not penetrate the panel in any way, reducing the chance of leaks in the roof.  This allows the panel to expand and contract as well due to change in temperature. The only problem with this type of attachment is the loading; the load is not absorbed by the structure, it is transferred to the panel, so testing also needs to be done to ensure that the panel fasteners can support the weight. If no testing is done, occasionally whole panels will shear off the roof sending not only snow but sharp metal sliding to the ground below.

The third method of attachment is gluing or adhering the device to the panel. This method provides the simplest installation and usually the least cost. From our experience with snow retention glue-on guards, they are typically high risk. More glue-on snow retention devices fail than any other type because of the many variables of installation. Adhesives require, in general, an approximate 30-day cure time of temperatures over 50 degrees. Many mountain areas drop below 50 degrees every night even in the warm seasons. These devices are usually made of a plastic material. Plastics can be damaged over time by UV-rays causing color distortion and brittleness. Over time the plastic and adhesive break down and have a greater chance of failure.

To sum it up when holding a large amount of snow in one place (like a large snow fence at the eave) something very strong needs to be used and should fastened through the roof into the structure. In most cases a clamp-on snow fence is the best method of attachment. These are less expensive; sometimes multiple rows may be needed. And remember—the panel also needs to be fastened sufficiently to hold the weight. Glue-ons can be used to save cost and labor, but will not provide the strength, life and reliability that a clamp-on system will provide. But, on occasion glue-on snow retention is the best option. In most cases mechanically fastening to the rib provides the best bang for your buck. Just remember to always consult with one or more manufacturers instead of designing something yourself; if not you may end up paying for it later when you get back up on the roof for a repair. Most manufacturers will provide recommendations and design free of charge with a quote.

Published: Metal Construction News | April 2006