Images from last weekend's tornado devastation in Joplin, Mo. and Minneapolis—not to mention last month's Tuscaloosa twister—may leave many homeowners wondering what, if anything, they can do to protect their property from such a horrific catastrophe. Images of flattened neighborhoods and trucks crumpled like paper underscore Mother Nature's power.

Homeowners insurance, though imperfect, is your first line of defense. If you haven't looked recently at your what's covered by your policy, this might be the time to do so—and to consider updating your coverage. Below, we list the basic coverages for single-family homes.

• Replacement cost. This more-common coverage pays only up to the stated value of the home. (Keep in mind that the stated value has to do with the cost to rebuild, not the market value; in today's real-estate market, the cost to rebuild may very well be higher than what your home could fetch in a sale.)

• Extended replacement cost. This provides more coverage than replacement cost, usually 20 percent over the home's stated value.

• Guaranteed replacement cost. This coverage is the most complete and is also quite costly. A few carriers offer the equivalent of this coverage, which promises to fully restore a damaged home, no matter what the cost.

The most-comprehensive coverage can be costly; you can ease the pain on your pocket by choosing a higher deductlble. Consumer Reports Money Adviser's analysis shows what a difference that can make over several years when you keep the same policy. Our Ratings of homeowners insurance (available to subscribers) discusses which companies provided the best claims service to our readers, a key consideration once the winds die down and the cleanup begins.