The installation of snowguards prevents the sudden release of snow and ice from the roof which can cause damage to people, pets, cars, landscaping, gutters, plumbing vents, lower roof areas, sky lights, and anything that might be in the immediate are below your roof.  Snowguards have been around for hundreds of years and have historically been use on slate, tile, and metal roofs.  There are many styles for residential and commercial roofs.