I have always found it interesting to review the budget summaries of the many timeshares I own.  They budget reserves (sort-of like a savings account for major repairs) for roofing, furniture, etc.  I was curious as to how long major components in my house should last and when could I expect them to go out.  I looked around and found a published detailed report from 2007 outlining most of the major components in a house.  You can view the Life Expectancy of Home Components Report by click the link.