I welcome the comments and the opportunity to further highlight the proper use of Snowgrip. Like every other material, product, or assembly that architects specify, or fail to specify correctly, the problems will long outlive the successes in terms of liability. We acknowledge the use of any product on historic buildings require an extra level of diligence.
In reference to the 140 year old slate roof mentioned in other comments, Snowgrip was not used on the building she discusses. Our system remains flexible (600% elongation capability after cure). Like all new products, Snowgrip needs more testing for many specific non-typical applications such as the 140 year old slate roof on a landmark building...We do know it has proven to be 100% effective in stopping snow slides on the roofs that have been treated to date....We have not installed on a slate roof yet.
As far as structural collapse from excessive snow load, it is logical to expect the maximum load on the roof to occur as the last flake of a snow storm falls and before the moisture (water weight) is able to drain from the snow pack....Theoretically the max load shall be the same on a Snowgrip roof as a non Snowgrip roof....One of the best properties of Snowgrip is the ability to promote melt water drainage efficiently and safely from the roof without allowing the snow pack to slide...It promotes the dehydration and substantial weight reduction of the snow pack. I would expect the recent collapses were associated with buildings that did not meet current code requirements or the load substantially exceeded the code required live load. I would be surprised if the recent storms cause code snow load tables to be revised throughout the country.
Not every building with a snow retention problem is an automatic fit for Snowgrip or any other system, but if a roof discharge just buried the family dog or worse, Snowgrip may be the right system even if the roof has 140 year old slate tile...research the problem...test it...solve the problem with the system that has the best pro to con ratio...If any cons are unacceptable, please find a new place for the dog house.
This response is from the manufacturer, Mark Blomquist, an architect practicing in the Upper Peninsula of Michigan.....the dog is safe by the way.....and they do get a bit of snow.
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Dennis Garde Assoc. AIA, LEED AP
Principal
Energy Veritas Ltd
Mt Prospect IL
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