International Association of Certified Home Inspectors

Components and Systems: How Long Should They Last?

System / Component	Average Lifespan
Central air-conditioning unit	15 years
Forced-air furnaces, heat pump	15 years
Furnaces: gas- or oil-fired	18 years
Water heaters	12 years
Roof: built-up or composition shingle	15 years

The information above was excerpted directly from Old House Web based on an article adapted from the U.S. Department of Housing and Urban Development's Residential Rehabilitation Inspection Guide (2000). The material was developed for the National Association of Home Builders' (NAHB) Economics Department based on a survey of manufacturers, trade associations and product researchers. Many factors affect the life expectancy of housing components and need to be considered when making replacement decisions, including the quality of the components, the quality of their installation, their level of maintenance, weather and climatic conditions, and intensity of their use. Some components remain functional but become obsolete because of changing styles and tastes, or because of product improvements. Note that the life expectancy estimates are provided largely by the industries or manufacturers that make and sell the components listed.

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