Owning a home means constant maintenance and repair. Doing the first helps put off the second. Many things, like plumbing and wiring, should last 50 years or more, but others like appliances, mechanical systems and surfaces exposed to weather and wear have far shorter life spans. On average, homes cost about 1 percent of their value in repairs in each of the first 10 years. It rises to 1-1/2 percent for each of the next 10 years, and hits 3 percent in each of the third 10 years -- coming to about 50 percent replacement over 30 years. But you can extend life spans, reduce costly repairs and put off eventual replacement by observing maintenance. For hundreds of ways to protect your old house, pick up our new book ?Home Maintenance for Dummies? (on sale at bookstores everywhere). And that's the On The House tip for today.