9. The Whole House Floods

ThisOldHouse.com: Top 10 Disasters That Can Hit Your House

Niles says aging washing-machine systems are notorious for busting when you least expect it. "A bulge in the hose line indicates it's weak and ready to go," he says. Check the hoses before you go, and turn off the water supply to the laundry area, just in case.

An aging water heater can also break down and send water cascading. "Lots of times there are signs that a water heater's failing," says Tom. "Water on the floor around it, or rust on the outside." Rust can mean that the sacrificial anode rod inside the tank has been depleted and the water

is affecting the tank itself. Tom suggests checking the anode rod and turning off the water supply before you go away. "That way if your it dumps out, the only thing that happens is you get a wet basement," says Tom.

(Photo: Deborah Waters - United Kingdom/Alamy)

More: Maintain a Washer and Dryer to Prevent Flood and Fire

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While You're on ...

A summer getaway is supposed to be a time for rest and relaxation. But if your heart is on vacation while your head is worrying about home, you won't get much out of your time off. That's why ThisOldHouse.com brought you this handy guide of the top 10 bad things that can befall your house when you leave it alone. Don't fret—they also share with you expert advice on how to avoid these pitfalls. That way, you can take off worry-free, and know that there will still be a house standing when you pull back into the drive.

(Photo: Roy Ritchie/Getty Images)

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1. Your House Bu...

One of summer's many lightning storms can start a fire, and with no one to call 911 it can take out a whole house. The best defense, says This Old House general contractor Tom Silva, is lightning rods. "This is not by any means a homeowner job," he warns. "You need a pro to install them." Any highly placed metal protrusion on your house should be grounded, in fact, including weather vanes and satellite dishes.

Don't overlook the health of your wiring, as well. Curtiss Niles of Armored Home Inspections in Upper Darby, Pennsylvania,

and President of the National Association of Home Inspectors, advises homeowners to keep up with maintenance. "Wiring is the last thing on a homeowner's mind, but I've seen exterior service cables in poor condition all too often." he says. "If there's short or a spark in the line, a fire can start, and you won't be there to put it out."

(Photo: Joel Sartore/Getty Images)

More: Fire Safety and Prevention Checklist

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2. Thieves Take ...

Unmowed grass, piles of newspapers, and revealing posts on Facebook might as well be an open invitation to burglars, says Ralph Sevinor, President of Wayne Alarm Systems in Lynn, Massachusetts. Sevinor suggests putting a hold on the mail, asking a neighbor to park in the drive, testing your alarm system, and keeping your travel plans off the Internet. "Even if it's your kid on Facebook telling her 2,300 friends about the family trip to Hawaii, you have to watch out. That message can get picked up by criminals who troll the Internet constantly," says Sevinor.

(Photo: Greenshoots Communications/Alamy)

More: Burglar-Proof Your Home

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3. The Attic Fil...

All it takes is one small entry point and wasps, bees, squirrels, or bats can take over this seldom-visited space. Then they build nests, chew through wiring or framing, or just make your home their final resting place. "Animals can get trapped and then die. After a few days, the stench can render a house uninhabitable," says Los Angeles–based architect Leigh Jerrard. "Make sure crawlspace and eave vents are securely screened with hardware cloth or welded-wire fabric," says Jerrard.

Tom Silva recommends that you do a visual inspection all around the exterior, both

before you go away and after you get back. "Look for vulnerable spots—holes under the soffit, flashing lifting on the chimney, rot around the windows," he says. "A bat can climb into a hole the size of your fingertip. Wasps and yellow jackets can find their way in through a tiny crevice." Patch, caulk, and replace as needed.

(Photo: Jacob D. Troost)

More: Pest Control: Keep Furry Invaders Out

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4. Your Lawn Die...

Extreme weather can kill your lawn, or leave it vulnerable to insects and blight, if you aren't there to catch warning signs. Billy Lee, a Master Gardener with Texas A and M extension service in Walker County, Texas, says that drought conditions can fry the grass, while excessive rain encourages disease. "My neighbors lost their lawn to a fungus called Take-all. They came home from a vacation and had to uproot the whole yard and start over." This Old House landscape contractor Roger Cook recommends asking a neighbor to watch out for wilt or brown spots in the lawn and leaving behind the number for your lawn service. "All you can do is depend on your good neighbor, and promise to do the same for him when he goes away," says Roger. "It's a fair trade."

(Photo: Courtesy Missouri Botanical Garden PlantFinder)

More: How to Rejuvenate a Dying Lawn

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5. Your Garden D...

The best defense against wilted flowers and shrubs is a well-established garden. "Older plants have had time to get acclimated and should survive a week without watering," says Roger. But a newer garden is more vulnerable. If you're planting just before going on vacation, mix Terra-Sorb into the soil. The crystals are designed to slow-release moisture, so plant roots won't go totally dry.

Container plants need more coddling. Billy Lee suggests placing plants in the bathtub and filling the bottom of the tub with water. Then put one end of some cotton rope in

the water and the other end in the pot. "The rope works like a wick and keeps your plants from getting thirsty." Better yet, says Roger, put the rope's end in the toilet tank; it will refill itself when the water level drops too low.

(Photo: Anna Stowe/Alamy)

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6. The House Sli...

Intense rainfall spells big trouble if your foundation is not up to snuff. Architect Leigh Jerrard knows of a house that slid right into the street after a blocked gutter redirected a few days of heavy rain into the foundation. "If that house had a good foundation it would have survived." says Jerrard.

If you know you have foundation issues, says Tom Silva, you have to be especially careful to keep water away. Grade away from the house, and keep gutters clean to keep them from overflowing and pooling water at the foundation. If necessary, put in

a French drain to direct the water to a storm drain. And install a sump pump if your basement fills often.

(Photo: iStock/Jacek_Sopotnicki)

More: How to Rejuvenate a Dying Lawn

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7. The Interior ...

Summertime humidity isn't just uncomfortable for you, it's a breeding ground for spores. Niles remembers inspecting an unoccupied home with the A/C turned off and discovering a subfloor covered with mold. "In the summertime it doesn't take much time for mold to grow—72 hours if the conditions are right.

Set the central air for 77 in the summer to keep the house dry and mold-free while you are away. Tom also suggests setting up dehumidifiers over sinks, so they can run constantly and drip into the drain. If you have double-hung windows with storm

windows, keep air circulating by opening the top sash while leaving the screen down over the bottom sash.

(Photo: Russel Kaye)

More: How to Allergy-Proof Your Home

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8. A Tree Falls ...

Storm season hits hardest in summer months, when fluctuating temperatures can cause heavy rain, wind gusts, and even hurricanes. High winds can blow down a dead tree limb, and over-saturated soil can cause uprooted trees. Roger Cook recommends having a certified arborist come out to evaluate the trees around your house. He will be able to spot rot or other issues that you might not recognize, and he'll know which types of trees are vulnerable to uprooting. An arborist can also help with trimming back too-close tree limbs, which should be 8 to 10 feet away from your roof, or balancing out a tree that is uneven and therefore more prone to topple over in a bad storm.

(Photo: iStock/AwakenedEye)

More: Working With a Tree Removal Pro

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9. The Whole Hou...

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.

10. You Ruin an ...

Many homeowners who are extra vigilant turn off the water and the power to their water heater before they leave, to avoid any risks of floods or fires. But that can spell disaster if you turn things back on in the wrong order; the tank needs to fill with water before you switch on the heater. John Palanca of Design Tech, a general contractor in New York City, says he's burned out the element in his water heater more than once at his vacation home when visitors turn it on with no water in it. "I keep extra elements around just in case."

(Photo: iStock/justnartist)