I am sitting in my office, looking out the window at our first snow storm of the year. I couldn’t help but wonder about the effects Snow & Snow Loads have on our buildings. So I did a little search and found an article posted on the InterNACHI website (embedded below) as well as a link to some additional information regarding “Snow Load”,
Medeek Design Inc – Snow Load, http://design.medeek.com/resources/snow.html.
I found the article from Nick Gromicko interesting. I have inspected snow guards in the past, as an attachment to the roof and always commented on how the added feature was installed or how it could affect roof coverings etc., but never gave much more thought to their importance.
Now we all have had experience of shutting a door hard and an avalanche of snow falls down the back of your neck, NOT fun, and thank goodness it wasn’t more than that. Snow and Ice can be very dangerous, please read Nick’s article below for more information about Snow Guards, also visit the link provided.
I found it interesting hopefully you do too. I will also be searching for more info. regarding effects on buildings, decks and other structures, check back soon for more fun facts!
Snow Guard Inspection
by Nick Gromicko
Snow guards are protruding metal or plastic devices (or lengths of bars) that are installed in intermittent locations on a roof that are intended to prevent accumulated snow and ice from sliding in great sheets off the roof. They encourage the gradual melt and breakdown of the snow mass into smaller sections. They vary in their method of attachment to the roof, as well as their color (they usually match the roof or are transparent), and their material (typically, they're made of metal or poly-carbonate).
Snow and ice are surprisingly heavy -- a single cubic foot of ice weighs more than 52 pounds -- and when they avalanche from a roof, they can cause a great deal of property damage and injury. Roof avalanches can injure pedestrians and livestock, bend gutters, and damage vehicles, lower roofs, HVAC equipment, and other property below. This typically happens when warm weather follows a snowstorm, creating melt-water that lubricates the roof.
In many cases, snow guard systems are not included during initial roof installations because of the additional cost and the general lack of awareness of their need. Nevertheless, building owners can be held liable for any property damage and personal injury resulting from excessive snow if it could have been prevented with snow-retention systems. Investing in the right snow-management system may mitigate liability, prevent property damage, and reduce threats to pedestrian safety.
Snow guards are not always effective or helpful, however; in very heavy snow, they may not be tall enough to resist the snow's downward force, and shingle roofs typically have enough resistance to hold the snow naturally. To act as effective restraints, snow guards should be installed by qualified roofers who can competently consider factors such as sheathing type and thicknesses, roof type, roof slope, and snow loads in determining proper snow guard sizing, design and placement. Homeowners and handymen who attempt snow guard installation may install them in an improper pattern, or only weakly attach them to the roof, which may actually increase the potential damage due to falling snow and ice. Also, snow guards should never be used as anchors in fall-arrest systems, as they are not strong enough to support roof workers, and the guards themselves may be damaged.
Snow guard placement should be consistent with the following safety and efficiency standards:
Thanks for reading my newest blog post, comment back if you’d like to start a dialogue regarding this subject.
Nick Gromicko, InterNACHI - "Snow Guard Inspection"
Mark Johnson - Certified Master Inspector