Most people think about their homeowners insurance only a few times in their lives - when they select their insurer, when they’re writing premium checks and when they have a claim. By the time something goes wrong, however, it’s usually too late to begin learning about your policy. Many so-called exclusions, though, vary by the insurer. If you know about them in advance, you may be able to switch carriers or buy extra insurance to stay protected. So pull out your policy and check for the following:

Mold & Water Damage A spike in mold-related claims at the turn of the century led most insurers to strike the coverage entirely from their homeowners policies. The frenzy over toxic mold reached a peak around 2002, the year television personality Ed McMahon filed a lawsuit against his insurer over mold that he said sickened his family and killed his dog. A huge increase in mold-related claims in Texas, California, Florida, Nevada and Arizona led insurers to eliminate or at least reduce their exposure. Most homeowners insurers now exclude mold from their coverage, said Frank J. Coyne, chairman and CEO for the Insurance Services office, which supplies statistical data to property and casualty insurers. Many insurers also limit how much they’ll cover for water damage. In fact, in some cases you may have trouble getting coverage for a home that’s had water claims in the past.

Sewer Backup The only thing more disgusting than a bathroom floor overflowing with waste is the fact that you may have to pick up the cleaning bill by yourself too. Sewage backups are frequently not covered by homeowners policies unless you purchase a special rider. Many homeowners who experience this particular disaster try to get their cities to pay for the damage, but governments typically aren’t liable unless the homeowner can prove negligence - and is willing to go to court over the matter. A cheaper solution is to check your policy, and if you’re not covered, buy the rider for $50 - $100.

Natural Disasters If your home burns in a wildfire, you’re probably covered if you live in a developed area. However, if you live in a remote cabin or your home is rattled apart by an earthquake, inundated by a flood or blown away in a hurricane, you may not be. The more likely you are to be a victim of a natural disaster, the more reluctant insurers may be to cover you. That’s why residents who live near the Gulf Coast or the Atlantic Ocean typically need to supplement their homeowners insurance with hurricane coverage offered by a high-risk pool (and the number of properties considered high-risk has risen since Hurricane Katrina). California residents, meanwhile, get earthquake coverage from the state-run California Earthquake Authority or from a handful of insurers willing to write earthquake policies. Many insurers also won’t cover fire risks for people who live in forests or far from fire stations. That’s true even though some of the biggest wildfire losses have come in developed areas: the Oakland Hills fires of 1991, for example, the Laguna Beach & Malibu fires of 1993, and the San Diego wildfires in 2003. Most of those homeowners had no trouble getting insurance before the fires, while their more remote neighbors often had to buy insurance from high-risk pools.

Floods, meanwhile, aren’t covered under homeowners insurance policies - something many Katrina victims learned. The National Flood Insurance Program, run by the Federal Emergency Management Agency, offers coverage. If you live in an area that’s prone to either floods or hurricanes, you need both wind and flood coverage.

If you’re the victim of a landslide, however, you’re pretty much on your own. That kind of earth movement usually isn’t covered, so it pays to get a geologist’s report before buying any home near a cliff.

Neglect If your home collapses because of a termite infestation, you’re probably not covered. Insurers expect you to take care of your home and deal with any maintenance issues on your own dime. Insurance generally covers sudden and unexpected losses, not losses from termites, rodent infestations or a water leak you never quite got around to fixing. You’re expected to detect the problem and prevent the situation from getting out of control. If you don’t, any damage done typically won’t be covered by your insurer. Bruce Johnson, author of “50 Simple Ways to Save Your House,” recommends you conduct regular inspections to detect such problems. At least twice a year, tour the exterior of your home looking for cracks, decay or water damage. Check the condition of the roof and inspect the basement or crawl space for other hidden problems, including rodent droppings, termites, leaks, etc.

Dogs If you own a Pit bull, Rottweiler or Wolf hybrid you may find your insurance gets more expensive - if you can persuade your insurer to cover you at all. Dog bites cost insurers over $300 million a year, and an increasing number of companies have a blacklist of breeds they won’t accept or charge more to cover. Pit bulls, which lead the Centers for Disease Control and Prevention’s list of deadly breeds, are particularly unwelcome. Other troublesome breeds include German shepherds, Rottweilers, Wolf hybrids, huskies, Malamutes and Dobermans. If your dog has ever bitten anyone, regardless of its breed, you’re probably going to have trouble getting coverage as well. Each insurer has different policies, though, so you may be able to find affordable coverage if you shop around. You also can ask the insurer to exclude your dog, meaning that you’ll pay for any damage it does.

Intentional damage Intentional damage by an insured person - or by the person’s spouse, children or relatives living in the house typically isn’t covered. Estranged spouses often come into a gray area. Although they may not live in the home, they may be listed on the policy or the property deed and be considered to have an insurable interest in the home. Companies have, in fact, made this argument to deny or limit coverage to homeowners whose property was damaged by an estranged spouse.

Computer Equipment If you have a personal computer or two, your homeowners insurance may pay you enough to buy a new one — or it may not. If you’re running a home business, however, your homeowners insurance almost certainly will fall short. Here’s another area where it pays to read your policy. Some insurers will give you a check only for what your computer equipment is worth now, which is probably a fraction of what you paid for it. Even those that do pay for replacements typically have a cap, often about $2,500. Many require you to have supplemental coverage if you want a bigger check than that, or if you run a business from your home.

Luxury Items & Collectibles If you don’t own anything special, the entire contents of your home are probably covered under your homeowners policy. If you have antiques, guns, jewelry, collectibles or fine furs, you may need extra coverage. The typical policy limits coverage for luxury items and collectibles. You might get as little as $200 for the coin collection you were hoping would fund Junior’s college, or $1,000 to cover all your jewelry, watches and furs. To make sure you have enough coverage for all your stuff, use the home inventory software available at the Insurance Information Institute.

Trampolines Insurers charge more for certain hazards, like pools and spas. Trampolines, though, are often excluded completely. They’re fun, but they also offer a lot of ways to seriously hurt yourself. That’s why your homeowners policy probably excludes trampolines from coverage and why your current insurer may threaten to drop you if you buy one. They simply don’t want to pay for the lawsuit and medical bills if the neighbor kid breaks something. If you insist on having one, you may need to shop around for an insurer that will tolerate, if not cover, trampolines.