The Cost of Upkeep

You'll also need to budget for regular maintenance, repair and eventual replacement of your home's major appliances and components, such as the furnace, electrical systems, roof and foundation.

According to a 1997 study by the National Association of Home Builders, annual spending on fuel averages 1.78% of a home's value. Homeowners spend another 0.46% of their home's value on other utilities, 0.50% on maintenance and repairs, 0.48% on property insurance and 1.29% on property taxes, for a grand total of 5.51%.

So if your house is worth $350,000, budget $3,500 for annual operating costs; if it's worth $500,000, plan on spending $5,000 a year; if it's worth $1 million, set aside $10,000.

Steve Melman, the NAHB's director of economic services, says that, in dollar terms, the costs of operating a home have risen since the study was published, thanks to the rising costs of fuel and raw materials. But property values have also risen in the interim, so the costs in terms of percentages of a home's value are probably still accurate.

The life expectancy of a typical appliance depends to a great extent on how much it is used, but of all the major appliances in your home, gas ranges have the longest life expectancy -- 15 years -- while dryers and refrigerators last about 13 years, according to another NAHB study. Some of the appliances with the shortest life spans are compactors, which last six years, and dishwashers and microwave ovens, which both last nine years.