We completely upgraded this home with an unbreakable composite Slate. The details are absolutely stunning and the strength and protection are even more incredible. With our method of installing this slate roof we have a: Class A Fire Rating Class 4 Impact Rating Practically Maintenance Free Lightweight a 50 yr Material Warranty We installed a two ply underlayment system and with two stainless steel screws on each slate. This extremely protective system is expected to last over 50 years while maintaining the gorgeous Slate aesthetic for a timeless look.