A snow guard system mitigates the risk of sudden and unexpected release of snow from the roof, which can lead to damaged roof panels, gutters, light fixtures, walls and foundations, protection of lower roofs or worse, severe injury to people. The idea is to evacuate the snow in a predictable and controlled fashion, as opposed to a sudden release. It may be hard to imagine that an accumulation of those pretty little snowflakes can have enough force to do serious damage to property and person, but that is the reality. Shop our snow retention systems here.
Snow retention has been used for hundreds of years in regions where snow accumulation on roofs is an issue. Technology has now changed from stones and logs to polycarbonates, zinc and aluminum. With the growing trend towards a more environmentally friendly construction industry, metal roofs in the commercial, industrial and residential markets are quickly becoming a choice of architects and roofers. Metal roofs are made from recycled material (steel and aluminum), and their longevity greatly surpasses that of a shingled roof. A metal roof can last upwards of 80 years and their reflective properties equate to lower cooling costs in the summer. With every new metal roof installed, there needs to be a properly designed and engineered snow retention system. A properly designed system needs to take into account the following factors:
Can the manufacturer provide load tests on the attachment method to the metal roof whether it is a standing seam or not? Are the manufacturer’s published load tests based on ULTIMATE loads or does the manufacturer provide both the ULTIMATE and WORKING loads? Working Loads are generally based upon a Safety Factor of 2 of the Ultimate Load, example below
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Manufacturer’s load test shows the attachment point to the metal roof has an ultimate load of 1000lbs, the ultimate load generally indicates some point of failure depending on the manufacturer’s testing protocols. Some manufacturers post the ultimate load as their working load which can quickly overload a snow retention system and possibly cause damage to the roof panel itself. An industry standard is to apply a Safety Factor of 2 to the ultimate load, which would be 500lbs; essentially dividing the ultimate load by the safety factor. In some cases a safety factor of 3 may be applied.
Are these results available upon request or do they magically appear when it comes time to close the deal. If the manufacturer CANNOT provide you with any load tests that have been certified by an independent lab or have been stamped by an engineer, then it is buyer beware.
For Standing Seam Roofs
- Roof Designed Snow Loads – these are based upon the National Building Code
- Slope or Pitch of the roof
- The distance from ridge to eave or the panel run of every roof that requires snow retention
- The assembly length of every roof that requires snow retention
- The gauge of the metal being used (copper or aluminum)
- The profile or fold of the standing seam profile.
- Spacing between seams
- Roof Designed Snow Loads – these are based upon the National Building Code
- Slope or Pitch of the roof
- The distance from ridge to eave or the panel run of every roof that requires snow retention
- The assembly length of every roof that requires snow retention
- The substructure to which the roof is attached (steel purlin or plywood)
Further considerations are dormers, overhangs and adjacent roofs that may shed onto a lower roof(s).
Snow Loads
In order to properly take into account loading on the Snow Retention System some basic information is needed.
It is misunderstood that putting a line of guards down the roof edge solves all my problems.
The issue that is not known is the fact snow loads vary from region to region, spacing of brackets etc come into play.
Snow along the row of guards adds loading to each connection point and if not designed or overlooked could exceed the load of what the bracket can hold and that a major problem.
Looking at this picture the system is a 3 bar system (2 bar system is more then what is required) and appears should have worked, but based on o the snow loads, eve to ridge the system was overloaded and failed. In most cases another row is required to reduce the loading on the next system.
Basic information required is listed below, IF YOU ARE UNSURE OF WHATS REQUIRED PLEASE FILL THIS FORM OUT AND E-MAIL BACK TO US OR GIVE US A CALL.
Snow Facts
The purpose of a snow retention system is to retain snow pack on a roof.
The idea is to evacuate the snow in a predictable and controlled fashion. In other words, evaporation and thaw rather than by a sudden and dangerous rooftop avalanche. Each roof needs to be analyzed, there are many factors that contribute to the loads imposed on any snow retention such as
- Distance between seams
- Length of the roof run (ridge to eave)
- Assembly length or eave run
- Slope of the roof
- If there are multiple roofs feeding onto one roof, do the valleys create a funneling effect.
- Does the roof(s) have a wider section at the top and taper down near the bottom which can increase loads where tapered edge finishes
- Roof snow loads
These are just some of the factors needed to properly engineer a snow retention system.In various section of Snow Facts we will try to help you understand what is required for putting the Snow Retention System together.
Placement of Snow Retention
This is the tricky part on where do you place the system and how often do they need to be placed.
There are many things to consider when locating the system on the roof
1) How much snow is there in any given area
2) Are there lower roof and dormers to contend with
3) How is the wind going to effect the placement of snow on the roof
These few pictures show how the wind and higher roof lines will tend to increase snow loads and could cause problems if not designed with this in mind.
In some case people will want to add just a small line of snow guards above a door to protect people entering or leaving a building. See Below
These are just some of the factors that come into play, if you are unsure please call or e-mail us and we will clad help you in any way we can.
Snow Falling from Roof
Here are a few videos to show just how falling snow can affect what happens at ground level if it's not maintained on the roof.
