When snow piles up on your roof it could eventually slide off on you or someone else. When heavy snows deposit lots of white stuff on your roof, radiant heat rising from your home eventually allows a thin layer of water to form between the snow and the roof surface. If you have a smooth roofing material -- such as slate, tile or standing seam metal -- the water acts as a lubricant, allowing big layers of snow to break off and slide down the roof slope over the edge onto whatever (or whomever) is directly below. The solution is to install roof snow guards. They're available in many different shapes and styles that work basically in the same manner. They hold snow in place with a series of small 90-degree "stops" that clip onto shingle edges or metal standing seams. The result: heavy snow stays in place.