For the purposes of a home inspection, the roof system consists primarily of the roof coverings, flashings and chimney. In addition to protecting the interior elements of the home the roof components should also be designed, in conjuction with the gutters and downspouts, to direct rainwater and runoff away from the foundation area, to help reduce the potential for soil erosion, compaction and water entering the basement area. Because of the important functions this system provides, it's condition should be assessed regularly, and maintenance provided when and wherever necessary. Most sloped roofs are covered with individual pieces of shingling material overlapped to prevent water penetration. The slope of a roof can be a factor in the life expectancy of the roofing material.
Asphalt shingling is the most common roofing material used in residential construction in Canada.
Other types of covering for sloped roofs include asphalt roll roofing, concrete or clay tiles, wood shakes and shingles, and slate shingles. There are also fibreglass shingles, metal shingles and metal sheet roofing systems. Flat roofs are built up with layers of molten asphalt and felts, or covered with a membrane of modified bitumin or asphalt base, or plastics or rubber. Most are heat-sealed and some are glued. Flashings can be constructed of galvanized steel, tin, aluminum, copper, lead or lengths of roll-roofing.