Snow retention systems should be installed on roof systems that will incur snowy winter weather. However, many people are unaware that snow guards are necessary until they incur damage to their gutter systems or injured below a fall.
The information below outlines some best practices for the homeowner to consider when choosing what style, what quantity, or installation patterns for their SEAM MOUNTED SNOW GUARDS.
DISCLAIMER: The following information is meant to be a guideline for general installation purposes. Every roof is unique. Factors like rafter length, pitch, snow load, panel type etc. all play a part in determining a proper layout.
A qualified engineer or architect will be able to make layout recommendations if required. Snow guard manufacturers like Alpine Snow guards or Berger Building Products are also capable of offering layout recommendations if contacted.
Snow Guard Positioning
Assumptions: <75 PSF (GSL – ground snow load), < 16/12 Roof Pitch
- How many Rows? : Alpine Snow Guards recommends a row of snow guards installed for every 5′ of rafter length.
- Staggered Pattern: Snow guards are usually installed in groupings of 2 rows staggered on every other seam. The picture below shows 4 rows. The spacing is of the two rows varies depending on which manufacturer you ask, but it is often the same width as the spacing between ribs. The picture below shows slightly more space at 24″-30″.
- First Row Positioning : The first row of your layout should be set back at least 24″ from the eave. Ideally the row should be positioned in line with the exterior wall. Imagine snow being held back at the point of the snow guard. You do not want all that weight to be hanging off the roof past the support of the exterior wall.
Torque Value on Installation
The stainless steel set screws in seam mounted snow guards are designed to dimple the metal without creating penetration. Torque for these set screws should be between 140-180 in/lbs. You should calibrate your drill after installing a guard and then testing with a torque wrench.
It is advised that you secure a screw and then the other, then return to each screw to secure a second time to ensure that they did not loosen.
S5! Snow Retention did a great video describing torque value and how to properly achieve during installation.
What’s the point?
Snow guards, when installed properly and in sufficient quantities, are non-negotiables on metal roofs in snow areas. The most common error is simply not installing enough snow retention.
Remember that the snow guards are meant to prevent the avalanching of snow off of the roof and rather allow the snow to melt overtime at a more even pace. The above information is all related to seam mounted snow guards for standing seam metal roofs. Rail systems will have separate layout requirements.
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