Understanding snow retention

By Emma Peterson. 

Looking ahead to the upcoming winter season, learn what snow retention is and how it keeps people and property safe. 

It might seem far away right now, but before we know it, we’ll be bundling up in warm jackets and hats for the winter season. And with that cold weather comes new challenges for your roof, like snow management! In this episode of the AskARoofer podcast, Lauren White chats with Brian Cross from Rocky Mountain Snow Guards, discussing how to best set your roof up for success this winter with a snow retention system.  

Understanding the dangers of snow accumulation 

Many people instinctively think that getting snow off their roof as soon as possible is the best wintertime practice but leaving the snow in place with the proper safeguards is often the safer choice. Brian explained, “When snow is falling, it'll make two kinds of bonds when it hits the roof. First is an adhesive bond, which is the snow sticking to the roofing material. The second is a cohesive bond, which is the snow sticking to itself.” The adhesive bond is what allows the snow to stick to your roof deck first, and then the cohesive is what makes it pack on top of itself (kind of like a snowball).  

Then, when the active snowing stops and the sun comes back out, its rays will shine through the translucent snow and warm the roofing material. This creates a layer of water between the packed snow and the roof. Brian elaborated, “At that point, the adhesive bond breaks and the only thing that's holding that section of snow is the cohesive bond. And once that cohesive bond breaks down under the sun’s rays, the entire portion of snow will come falling off the roof in an avalanche.” 

These avalanches are one of the biggest dangers related to roofs in the wintertime. They not only can cause damage to the property underneath but can also harm people and pets if they are in the wrong place at the wrong time.  

What can you do about it 

The best way to manage snow on the roof and keep these dangerous avalanches from occurring is by installing a snow retention system. Brian explained, “A snow retention system is usually comprised of units or bars that go on the roof either in certain patterns or across the eaves. This is going to maintain the snowpack. So, with the adhesive bond being broken, the snow retention system is there to essentially act as that bond and keep the snowpack where it is, letting it trickle off in a melt instead of avalanching.” 

There are three main types of snow retention on the market:  

1. Snow guards: These are individual units whose “effectiveness comes from the pattern that they're installed on the roof.” 
2. Snow fences: Attached through mechanical fasteners, these feature round piping that spans the side of the roof. Two or three are usually installed at once. 
3. Snow bars: A great example of this type of retention is the S-5! Color Guard system, which is a single bar that goes along the edge of the roof line at about two inches in height to catch the snow before it can slide off.  

These different systems can come in everything from plastic to copper, steel and aluminum, making it easy to find something that will work with the aesthetics of your existing roof while also offering you security and safety through the winter. 

Tune in to the full podcast to learn more about snow retention.