Green Roofs

The green roof of this unheated porch in the Chesapeake Bay area absorbs 27 percent of the rain that falls on it, reducing storm-water runoff that might pollute nearby rivers and streams. Homeowner Mark Gaulin, a roofer, installed "chicken ladders" to facilitate twice-yearly weeding of the roof, which is planted mostly with sedums, a family of hardy, drought-tolerant perennials.