In September, we asked for your questions on exposed-fastened (EF) roofing. Thank you for your responses! We collected them and thought we’d answer one of your questions today. A reader asked us why it made sense to install snow stops on an EF metal roof. If your building is in a snowy climate, installing a continuous snow fence, or discontinuous snow stops or snow guards is essential. For your system to be effective, however, the installation must be well-designed and by calculation – not by “guess and by golly.” There are common misconceptions around snow and metal roofing. So, today we’ll cover why a qualified snow retention system properly engineered for your specific installation is important to EF roofing in heavy-snow regions.

Massive snow accumulation on a roof creates the potential for an unpredictable avalanche-like effect. Metal is a great choice for your rooftop. It has a long life expectancy and can stand up to the harshest conditions. It does have a low coefficient of friction though–meaning things (including snow) don’t stick to it very well. But the notion that snow is intended to slide off a metal roof is misguided and can be dangerous.  

It is a sudden release of snow off a rooftop. Falling snow forms a temperature-sensitive bond to the surface of a metal roof. As that roof is warmed, (through sun or building heat loss), the bond with the snow is broken and a thin film of melt water lubricates the roof. This sudden release from a rooftop can dump many tons of snow below the eaves in a matter of seconds, endangering building elements, landscape, vehicles and pedestrians.

Snow retention helps preserve your metal roof and allows snow drifts and snow melt to exit the roof in a more controlled manner (i.e. in small amounts, evaporation or melt water), avoiding the potential calamity of the rooftop avalanche.

Our two-part series is on the S-5! Snow Guard Calculator. Step 1 covers exactly why it is so important to engineer your snow guard system. In Step 2, we'll explain how to log on and get started with your calculation!

Snow retention systems go by many names in the industry. Roof snow fences, snow rails, snow stops, snow stopper, snow guards, snow clips, snow bar, and more. Regardless of the phrase, the intended purpose is the same: to reduce the risks associated with rooftop avalanches. By holding back the snow and encouraging it to leave the roof slowly through small amounts or melting, damage to walls and foundations can be reduced.

This is Part Two of a two-part series on qualifying snow retention systems.

In Part 1 of What’s on Your Roof? we discussed how, unfortunately, there aren’t any snow guard police out there patrolling the industry. This creates a two-fold problem: One, that you can’t count on there being building inspectors to check a go-to-market system for structural adequacy; and two, architects and installers of these systems can potentially be sued for personal and property damage from faulty snow retention systems they specify or install.

At S-5!, we don’t recommend installing adhesive-mounted snow guards on metal roofs. From both an economic and design perspective, glued on plastic snow guards typically have low holding strength and are unable to handle harsh weather-related elements. The bond weakens over time and when it fails, the guard can rip away paint and protective roof coatings, potentially leading to corrosion.

When a snow avalanche falls off of a rooftop, it can damage anything in its path! This sudden release of snow can be dramatic—dumping tons of snow in mere seconds. Falling snow forms a temperature-sensitive bond to the surface of a metal roof. Then, when that roof is warmed, whether from the sun or from building heat loss, the bond between the snow bank and roof is broken and a thin film of melt water serves to lubricate the slide.

Metal roofs are a smart decision. But with metal roofs, you must consider the risk of roof top avalanches. A quality snow retention system will help you maintain your roof, avoid personal and property damage, and efficiently and safely allow snow to melt off your structure. But there are a number of methods to mount snow guard systems. What is the best way?

First you need to determine what type of metal roof you have. S-5! Provides various solutions for all metal types and profiles. One of the S-5! clamp products will be suited to your standing seam (concealed fastened) metal roof. So which standing seam roof profile do you have? Let’s take a look at how to make that determination.