There are hundreds of clues that suggest the age of a house. Here are just a few of them.

Like all good rules, there are exceptions. Use these carefully, and don't be surprised to find conflicting information.

House components are replaced over the years, and in some cases, used components are put into houses. Location, is of course, an obvious place to start. Houses in the same area tend to be built at the same time. Architectural styles do help, but there are textbooks written about this subject.

These construction materials and practices should provide some assistance:

• Stone foundations - pre 1930
• Brick foundations - pre 1935
• Sculptured concrete block foundations - 1920's to 1940's
• Solid masonry (not brick veneer) construction - pre 1970
• Plywood subflooring - post 1965
• Brick chimneys without liners - pre 1950's
• Metal chimneys - post 1960
• Aluminum wiring - 1965 - 1978
• Knob-and-tube wiring - pre 1950
• Grounded (three-prong) electrical outlets - post 1960
• Copper supply plumbing - post 1950
• Copper main waste stacks - 1955 to 1970
• Plastic waste plumbing - post 1965
• Drywall (versus plaster) - post 1960
• Urea Formaldehyde Foam Insulation - 1970 - 1980
• Sealed double glazed windows - post 1950 (look for date on beading between the panes.)
• Hardwood floors - pre 1960's (popular)
• Gravity furnaces - pre 1972
• Toilets - date often stamped on underside of tank lid or on tank walls
• Aluminum siding - post 1945
• Vinyl siding - post 1968

Compliments of:
Carson Dunlop & Associates Ltd
Consulting Engineers - Building Inspections
597 Parliament Street, Suite B5
Toronto, ON M4X 1W3