Roofing, Flashings, and Chimneys
Introduction
The primary function of the roof system is to protect against and manage the weather elements, particularly precipitation, thereby protecting the interior and structural components of the home. 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.
Roofing
There are two basic types of roof construction, sloped (also called pictched) and flat. Most sloped roofs are covered with individual pieces of shingling material overlapped to prevent water penetration. flat roofs are basically watertight membranes that should have just enough slope to allow water to run off. The slope of a roof can be a factor in the life expectancy of the roofing material. The life expectancy of a roof covering is also dependent upon the type of material used, the quality of workmanship, exposure to sun and wear from tree branches, snow/ice and wind. For example, south and west roof faces have a higher wear factor than north or east exposures, highly reflective shingles tend to have a longer life expectancy, and cement or slate roofs last much longer than standard ashphalt shingles (and cost a lot more!)
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
The purpose of flashings is to prevent the entry of water at areas on a roof where two components join together or intersect (i.e. one roof to another or a chimney thru a roof). Flashings can be constructed of galvanized steel, tin, aluminum, copper, lead or lengths of roll-roofing. The choice of flashing material will
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