One of the most important aspects of a house is the roof. A variety of roofing materials is used in the Northwest.

Asphalt composition is the most economical roofing material. The roofing materials often carry a manufacturer's warranty of 20 to 30 years. It can be applied over an existing roof provided no more than two roof coverings are already in place. Good service can be expected if proper maintenance and good ventilation are maintained.

Cedar shakes were quite prevalent and readily available in years past. A good shake roof, properly maintained, can last 15 to 25 years. Cedar roofs require periodic cleaning and a treatment with wood preservative. The lack of first growth cedar and the inability to verify the source of most shakes make them a very expensive roof with an often uncertain life expectancy.

Flat roofs and roofs with low pitch were often covered with a buildup of building felt and hot tar. Such roofs are usually covered with gravel or fibrated aluminum coating to minimize deterioration and aging due to heat buildup. These roof coverings are being rapidly replaced with newer materials often referred to as torch down, modified bitumen, or EPDM (ethylere propylene diene monomer). The material is applied using a torch to provide a single roof membrane. Compared to their hot tar predecessor, these roofs provide a long (20+ years) life with only routine maintenance.

Other roof materials include clay and concrete tiles and metal (corrugated and standing seam). These materials can have unlimited life expectancy but require special consideration in terms of installation.