By Brion P. McMullen, Bio
A professionally designed and tested snow guard system that is properly installed should last the life of the roof. Here is a brief overview of the most common problems we encounter when marketing snow retention systems and solutions on how to overcome them.
Poor Product Design and Lack of Testing- Due to some very basic rules of physics, the most efficient designs for pad style snow guards are those with a 3”-5” wide forward mounted flat face with solid support struts and base. The material should be 100% prime virgin grade polycarbonate that is UV stabilized. An alternative material we use is American Made 304 Stainless Steel.
Solution – Invest in a quality product, preferably made in North America by a reputable company willing to provide independent test results and stand behind the products that they sell. Ask for professional test data and warranty info. In the snow guard business, the difference between the cheapest guard and quality snow guards is only a few cents so shop for the best value, not the cheapest price.
Non-“Project Specific” Layouts- The layout of the snow guards on the roof is the most critical element in the entire system. “If the snow guard is the heart of the system, then the layout is the backbone.” Therefore the best value is in the correctly designed snow guard system installed with a professional layout.
A reliable layout will have multiple staggered rows of guards, with each guard mounted in the center of the panel valley where the snow and ice actually moves. Snow guards should be designed toeither mount on the flat of the panel or to straddle a minor or stiffening rib in order to get in the center of the valley. A proper snow retention layout with multiple rows will equally distribute the snow load across the entire roof section by minimizing movement of snow and ice. When we design layouts, we avoid doing anything that might do structural damage to the roof or panel damage due to unbalanced loading. The row spacing is not something to estimate or guess at based on what your neighbor’s house has. It is determined by a number of factors including panel valley width, Ground Snow Load Rating, run length (peak to eave distance), and pitch. This data is then matched with the strength rating of the product that is being proposed for the project.
We have spent 35 years perfecting our layouts and were the first to have made the estimating software free to the public at www.SpacingTool.com. All that you need is your dimensions, pitch, and Ground Snow Load. A custom layout will be emailed to you showing the exact recommendedplacement and parts list needed for your project.
Solution- Invest in a quality product that is matched to your panels and take the time to verify your local Ground Snow Load and pitch. Run a layout on SpacingTool.com and stick to the design. If you choose to use one of our products, you will have the assurance of a lifetime warranty. Don’t take layout advice from anyone that isn’t willing to stand behind the design and replace their failures.
Seam Mounted Snow Guards- We replace individual seam mounted systems quite often and the seam damage left behind is stunning. This type of guard usually has set screws and mount directly to the high seam. Because the design puts the face on top of the seam, there is no possible way for the guards to stop the movement of snow and ice other than what is above the seam. Gravity keeps the majority of the snow load in the lowest part of the roof panel known as the valley which is located below the face of the seam mounted guard. This is also where the snow and ice actually moves.
The other glaring issue is the seam damage, as snow and ice impact the sides of the guard’s face, it tends to torque the guard back and forth. Because of the wide faces and narrow seam mount, there can be a lot of torque applied at the mount. This results in the guards being ripped from the seams leaving behind scratches, bent seams, and possibly a voided roof warranty. These guards are usually made of cast aluminum rated in the 20,000 lbs. to 40,000 lbs. range, far stronger than even the heaviest standing seam. Therefore, if load is applied to only one side of the guard, the seam is often damaged from the resulting torque.
Solution – Avoid mounting any system to a standing seam that isn’t stabilized with bar and clamps at every seam. Use a bar system or adhesive mounted guards instead of individual seam mounted guards to protect the seams from damage. This distributes the impact force/load to all the seams, not just one.
Snow Bar Systems- Bar systems are extremely reliable and failures are usually caused by one or more of these factors.
1. Insufficient layout with either too few rows or rows not evenly spaced up the roof area is the number one cause of failure. Having too few rows of bars is generally caused by the installer or property owner not following the recommended bar layout. The bars can only hold so much load before they fail and come apart, multiple rows keep the snow and ice from building too much load/velocity as it slides.
2. Cheap bar system designs that skip seams when bidding jobs. It is also recommended to install clamps at every seam as an added safety factor. It helps protect the seam from damage by evenly distributing the snow load across entire roof area.
3. Untested, cheap homemade bar systems have a high rate of failure and can cause severe damage to the roof panels during failure.
4. Poor product designs that allow the snow to come off the roof even if the bar is properly installed and stays in place. Round bar and angled “Icestoppers” that “ramp up” are two examples of this. This is why we only use flat faced bar and perpendicular IceStoppers.
There are product designs that simply don’t perform as well as others, but let’s focus on actual failures.
The photo below is a perfect example of what not to do. This 3 row S-5! system was not evenly spaced up the roof area, thereby allowing the snow and ice load to slide freely down most of the panel until it slammed into the top row of bar. This system also used round tip set screws and a lightweight aluminum bar which allowed the clamps to slide down the seams while leaving deep scars in the metal. Cupped tip set screws are proven to be far more efficient at staying in place under load and don’t require high torque on the set screws during installation. For more info on set screw testing, visit www.truthaboutsetscrews.com. Had we designed this system, it would have had 3 evenly spaced rows of heavyweight aluminum bar and attached with cupped tip set screws to 90in/lbs torque. It would have been backed by a free lifetime warranty against situations like this.
Solution- Only use a reputable bar manufacturer that provides a full layout and offers a free lifetime warranty on performance, parts, and finish. You shouldn’t have to pay extra for a product warranty to get it to work properly. Insist on using only square bar or flat extruded designs clamped at every seam, round bar has a tendency to allow the snow and ice to go through the bar. Also be sure that the ice stoppers mount perpendicular to the roof panel, angled models will cause snow to “ramp” up and over the clip thereby defeating the purpose. A properly designed bar system will outlast the roof and whatever Mother Nature throws your way.