Next time you throw a party on your deck, think about what’s holding you and your guests up.

Last month, a deck collapsed at a home in Surgoinsville, Tenn. injuring 6 people. The likely culprit was rotted wood.

According to the North American Deck and Railing Association (NADRA), an estimated 40 million residential decks in the United States are more than 20 to 30 years old.

If you own a deck, taking care of and inspecting it should be on your annual home maintenance checklist, especially if you live in the humid Southeast or the frigid North, according to UL consumer safety director John Drengenberg

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“If you have a big crowd on your deck, it probably wasn’t constructed for 20 people out there,” says Drengenberg. “Sometimes, that’s when they break or fall. For example, the wood is rotted or the bolts that hold it to the structure are coming out.”

Inspectors are responsible for making sure the deck is structurally sound when it’s being built, but it’s your responsibility to keep up with maintenance after that, says Drengenberg.

Here are six steps to keeping your deck in top shape.

Look for signs of wear and tear. “Look at the nails, the wood and the flashing [a plastic guard that directs water away from the deck]. If you’re in the southern part of the United States, rotting could be an issue due to heat and moisture. If you are in the northern part of the country, you may be subjected to heavy snows, wind and weather of all kinds,” says Drengenberg.

Don’t forget the stairs. If your deck has stairs, check them too. They can collapse if not well maintained, says Drengenberg. Check the railings and bolts for signs of decay, advises the NADRA.

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Check for rotten branches hanging over your deck. A rotten tree limb could fall on your deck, with grave results.

Rethink your power sources. Throwing a party? You may be tempted to string the deck with pretty lights. But first, "make sure your GFCI-type electrical outlets and switches are certified for outdoor use since they are exposed to the elements,” says Drengenberg. The lights need to be certified for outdoor use as well. And don’t let them create a tripping hazard.

Grill safely. “Be very careful with your grilling, especially with charcoal. If some of the ashes land on the deck, they could start a fire and it could damage much more of your home than just your deck,” says Drengenberg. NADRA suggests protecting the deck surface under the grill with a non-flammable pad.

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Keep your deck clean. Falling leaves and debris can cause the deck to rot faster, says Drengenberg, so keep the deck clean. You should also use a good sealer to seal the deck surface, railings and steps to make sure whatever water hits the deck evaporates. If at any point you see mildew, clean it off immediately and apply a new layer of waterproofing sealer, the NADRA recommends.

Muriel Vega is a writer with a passion for budget travel and staying safe while abroad. A Georgia State University graduate, she has over 6 years of editorial experience and has written for The Guardian, The Atlantic, The Billfold, among other outlets. In her free time, you can find her baking pies, playing with her two dogs and cat, or planning her next vacation. She spends way too much time on Twitter, one of her favorite social media channels. Her favorite safety tip: Make sure you have all the necessary shots before you go abroad.