8 Ways Your Deck Can Injure You
Experts say that as many as 20 million backyard decks in the United States aren’t built to code. Find out what you need to know to avoid injury or worse.
Deck and porch failures cause a significant number of injuries in the U.S. each year. During a 5-year study by the Consumer Product Safety Commission (CPSC), approximately 224,000 people suffered deck-related injuries. Of these, 33,270 people were injured as a result of a structural failure or collapse, and 18,000 of these injuries were serious.
Complicating the situation even further, about half of the 40 million residential decks in the U.S. are more than 15 years old—and the lifespan of a traditional wood deck is only 10 to 15 years. Not only are these older decks subject to natural wear and tear, but they were also constructed before today’s more stringent codes. As a result, to prevent deck-related injuries, it is crucial to maintain and improve existing decks. If you have recently bought a home with a deck and decided against an inspection before sale, it’s best to hire an expert to check it before using it, especially before you throw a big party. (If you don’t know a local professional deck builder, the North American Deck and Railing Association has a searchable member directory.)
No matter the age of the deck or who built it, it’s crucial that you check your deck at least annually and keep an eye out for problems year-round. Here are eight potential deck hazards to consider as you assess your deck, and why keeping each in check is important for the safety of your family and friends.
1. Deck guardrail spacing is too far apart.
Railings are a main focus of deck safety, and rail spacing—specifically, the spacing between individual vertical balusters (often referred to as spindles or pickets by homeowners)—is an important part of a deck’s design. These must be spaced so that a 4-inch sphere can’t pass between two adjacent spindles or pickets. If the rails are farther apart, then there’s a risk that a child’s head could pass through and become caught between the rails.
While 4-inch spacing is a requirement when building a new deck, it’s also a good idea to check this spacing on existing decks. Deck railings can become loose over time and wiggle enough to allow a sphere of 4 or more inches to pass through.
Note: One exception to the 4-inch rule concerns the triangles of space formed by the risers, treads, and the bottom rail of the deck’s guardrail. These triangular openings can allow a sphere of up to 6 inches to pass through.
2. There are no guardrails.
Guardrails are crucial for preventing accidental falls, and falls in general account for 1 out of 4 deaths at home, according to the National Safety Council. All decks need to have secure guardrails that rise at least 3 feet from the decking surface.
If there is a built-in bench along the edge of the deck, most municipalities require guardrails to be 36 inches above the built-in surface. Some municipalities may require taller guardrails to prevent falls.
Note: Guardrails aren’t required for a deck that’s less than 30 inches off the ground.
3. The ledger board is not connected properly to the house.
Why do decks collapse? When a deck that is connected to the house fails, it usually falls toward the house structure because the connection between the deck and the house has been compromised. Along with appropriate sizing of structural members and post hole depths, the connection to the house is a critical part of deck safety.
Decks should be connected to the house with ½-inch bolts or lag screws through a ledger board. Flashing must be installed to protect the ledger board and house structure from becoming compromised by weather. If the board is not flashed properly, or if deterioration occurs despite the flashing, water can collect behind the ledger board. Over time the fasteners and ledger board (and even the house structure) can decay, and this can eventually cause the deck to collapse.
4. Decking becomes slippery due to algae or ice.
A wood deck that doesn’t receive enough sunshine can require more upkeep and is more prone to slippery algae growth and deterioration. For those who have shaded backyards, a composite decking material is usually the best bet to reduce the opportunity for algae growth. However, a composite deck can be more slippery than a wood deck.
No matter the material, it’s important to care for the decking by removing leaves and debris regularly, and using an appropriate cleaner like the Wet & Forget Outdoor Cleaner, rated best for mold and mildew in our researched guide on the best deck cleaners.
Decking that’s covered in ice is another slip hazard. Consult our article on melting ice without ice melt for options for keeping ice at bay, but note that the best method will depend on the type of decking material you have.
5. Posts are undersized or decayed.
Decayed or improperly sized posts can cause a deck to fall. If built to current code, deck posts will be 6×6 or larger, centered on footings, and made of an approved preservative-treated wood rated for ground contact. To protect deck posts so they last longer, try Post Protector, an in-ground slide-on post barrier available at The Home Depot.
While these general parameters for deck posts help keep a deck structure sound, deck posts are made of organic material, so they eventually degrade. If you notice any post decay, schedule an inspection by a professional before using your deck.
6. Fasteners are missing or decayed.
Every fastener location on a deck is a potential failure point, and there are a lot of them. Deck building code in most municipalities dictates that all fasteners and hardware used with preservative-treated wood must be hot-dipped zinc-coated galvanized steel, stainless steel, silicon bronze, or copper. Decks within 300 feet of salt water need to have fasteners made of 304 or 316 grade stainless steel.
At least once a year, walk around the deck and tighten or secure any loose fasteners, replacing rusted or otherwise deteriorated fasteners as necessary. Oxidized metal can eventually deteriorate the surrounding wood, so what started out as just one unstable connection could damage the structural integrity of the entire deck.
7. Decayed decking can become loose and unstable.
If not properly cleaned and sealed annually, wood decking can quickly deteriorate as water settles into tiny cracks and expands those tiny cracks into big problems. As well, fasteners used to connect the decking to the joists can become loose or raised, becoming especially hazardous to pets’ paws and bare human feet. When the connections are loose, deck boards can become unstable and unsafe to walk on.
Make sure to care for your backyard deck using the appropriate methods for your deck material and the best sealers, such as Seal-Once Marine Premium Wood Sealer, rated best overall in our researched guide on the best deck sealers.
8. Stairs can become unsafe.
Deck stairs are subject to all of the potential hazards previously mentioned on this list, including an unstable connection to the deck surface and missing or improperly sized guardrails. Regularly check the stability of guardrails along the stairs, and be sure to keep the stairs well lit and clear of debris to ensure the safety of everyone who uses your backyard deck.
If you feel any sway or sag when using the stairs, check the integrity of their connection to the deck, and examine the fasteners used between the stair stringers and the deck’s rim joist. Do not use the deck stairs until they have been secured.