How to be sure you can rebuild your home.

Read any good insurance policies lately? You might be surprised by a plot twist in the fine print: Major homeowners insurance companies, including State Farm and Allstate, no longer promise to pay whatever it takes to rebuild your home if disaster strikes. Instead, the burden is on you to make sure that the stated coverage would provide enough to rebuild--although some insurers will agree to add in a buffer of 20% or so.

For example, State Farm offers a 20% cushion, known as "Option ID--Increased Dwelling Limit," to homeowners whose policies cover 100% of State Farm's estimate of the home's replacement value. The buffer does not cost extra, but you have to make sure it's included in your policy. Allstate caps its payout at 120% or a policy's stated coverage amount, too, but you don't have to request the extra protection to get it.

Companies say they have jettisoned the guaranteed-replacement promise because some homeowners were deliberately understating the value of their homes (often by neglecting to report improvements and additions) and counting on the guarantee to bail them out in case of a catastrophic loss.

IT'S YOUR PROBLEM. Now that guarantees are history, any miscalculation will be your problem, not the insurance company's. And when you consider that the common wisdom is to build a cushion of at least 10% into any remodeling budget for unexpected expenses, a 20% buffer doesn't leave much room for error.

Your insurer will estimate how much coverage you need, but how do you know if that estimate is correct? It might not be, but it's bound to be closer if you take these precautions:

* Tell your insurance agent about any remodeling that you've done, even if you only upgraded your kitchen appliances.

* Ask your agent to make sure that your policy includes an automatic annual adjustment for inflation.

* Get policy quotes from a couple of competitors--and compare the coverage amounts they recommend.

* Get your own estimate of rebuilding costs, and compare that with the insurance company's figure. For a rough idea, start by figuring the total square footage of your home, upstairs and downstairs. (You may find those numbers on your copy of the survey filed away with your mortgage papers.) Then multiply the square footage by the local cost of construction per square foot. Contractors should be able to give you a ballpark figure.