To determine what makes a green roof, we must first consider what a roof does. First, and foremost, roofs keep rain (and snow) off our heads and protect the walls and interiors of our houses; second, they keep us safe from fire; third, they add to the curbside appeal of our homes; and finally, roofs can provide temperature abatement. When you hear the term green roof, you may invoke images of environmentally friendly, flat garden roofs with multiple types of drought resistant green plants spouting up. Green roofs comprised of plants weigh about 15 lbs per square foot, often requiring added structural support, and green roofs are generally designed for flat roofs or those with an extremely low slope. In areas where there is snow, there could be concerns with the added weight. Then, too, in the first year the green roof must be irrigated and weeded regularly. In subsequent years, a green roof must be weeded at least twice a year. Ideally, green roof products, which are better for our health and for the environment, would provide all four of the above benefits. But it's not always that simple. Roofing can be one of the most climate-specific materials for building. Green roofing materials and durability go together. Durability is synonymous with longevity, hence, green. The more durable a product is, the longer it remains in service and the lower the total cost to the environment will be, conducive to the green roof concept. Using durable products also reduces pollution and landfill waste.