Longevity on the Home Front: How Long Will That Furnace Last?

by David Tenenbaum

You want your house to last forever, and some of it probably will. You may recognize that some parts of a house are more prone to failure than others, but which parts, and how long before they need replacement? New information from the National Association of Home Builders, Washington, D.C., Study of Life Expectancy of Home Components gives an up-to-date picture of longevity on the home front.

Your home is most likely your biggest investment, but it's an investment that needs care and feeding. If you have a mortgage or home equity line of credit on your house, repairs and replacement become part of your cost of capital. But the most obvious reason to think about longevity is because it will motivate you to save for the inevitable upcoming expenses: You always can delay a remodeling project, but not the replacement of a furnace or roof.

Like the military's "mean time between failure" statistic for jet engines, longevity numbers give a rough estimate of the expected lifetime of particular components of a house. But the numbers are subject to many caveats. The data were compiled from manufacturers, trade associations, and researchers, some of whom could overstate the durability of their products. Only good quality material—properly installed and maintained—will achieve the estimated lifespan. And weather plays a major role: A dry environment usually is more conducive to longevity than a damp one.

Finally, these averages only apply if you keep the entire building in good shape. If your foundation cracks due to unstable soil or flowing water, your floors may sag and your walls may crack. When your roof or plumbing leaks, the drywall, plaster, and framing can suffer premature failure.

If you average out all the various parts of your house, the law of large numbers will come into play: Your replacement costs may hew closer to the average than you expect.

The table below lists life expectancies for home components. Many items omitted from this list have a life expectancy of 100 years or the "lifetime" of the building, including:

• All masonry and concrete products (except driveways), including foundations, walls, and countertops, such as stone and granite.
• Siding--vinyl, cement, stucco, brick, and manufactured stone. Note: Aluminum siding was not listed, but is quite durable.
• Drywall, plaster, wood, steel, and concrete framing.

Click to enlarge

Dave Tenenbaum is the author of "The Complete Idiot's Guide to Home Repair and Maintenance.

Published October 8, 2007

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