Understand your roof's type in relation to the various styles of metal roofing and their potential attachment limitations. Some roofs are screwed down and can accommodate a mechanically mounted snow retention system, but some property owners may not want to drill any new holes in their roof. In that case, they can go with an adhesive-mounted polycarbonate snow guard. A screw-mounted snow retention system is not recommended on most standing seam metal roofs and may void the roof warranty. The most common snow retention options are screw down snow guards and snow rails, seam-mounted clamp-on snow guards and snow rails, or adhesive-mounted polycarbonate snow guards.