The sudden and unexpected release of snow from the roof can be dramatic, posing a serious threat to property and passers-by which is why Snow Guards need to be thought of as a safety system and not just an add on at the last minute. A properly engineered snow guard should last the lifetime of the roof, have published and accessible load tests results that a professional engineer is willing to stamp. Far too often snow guards are simply attached by sheet metal screws with little thought to the snow loads placed on the system. If the snow guard supplier cannot provide load tests, or if an engineer is not willing to sign off on the system then walk away.
The PDF outlines the importance of and engineered snow guard system