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  • John Esposito

How safe is your deck?

Spring will be here before long, and that means we can finally spend some time outside! Outdoor living is all about relaxing and having fun, especially on your deck. But before you start marinating those spiedies, or plan this summer’s big bash, take some time to ensure your deck is safe and structurally sound. The weight of people and objects on a deck, coupled with movement, create vertical and horizontal forces. As the weight shifts during normal activity (imagine people on a deck during a party, or your children running across the space), the fasteners are pried away from the ledger bit by bit. Add in the fact that wood will expand and contract as temperatures and humidity levels change, and it’s easy to understand why the nails might pop out of the ledger board.

In the United States alone, there are 40 million decks in use that were built 20+ years ago, according to the North American Deck and Railing Association. Building codes, construction methods, and decking materials have changed significantly since then. Add in the fact that decks are outdoor structures constantly at the mercy of rain, sun, snow, and extreme temperature fluctuations, and it’s easy to see why an annual deck inspection is a smart idea.

Perhaps your deck isn’t that old, or it’s built with composite materials? In all likelihood the substructure is wood, and wood is highly susceptible to rotting, splintering and warping. So, no matter how beautiful and strong your deck may appear, take the time to inspect it. After all, wood rot is one of the main culprits responsible for deck failures. Ledger board issues are another concern – and the main reason decks collapse. Approximately 90% of deck collapses occur as a result of the separation of the house and the deck ledger board. Even decks that were professionally built, and approved by code enforcement, can become weak over time.

Fortunately you can probably perform a safety check yourself. Some important things to look for are:


  • First and foremost is to ensure your deck and stairs are structurally sound – there should NEVER be any movement or swaying whatsoever! Also check to make sure the deck hasn’t tilted, or become unlevel due to ground heaving.

  • A leading contributor to deck failure is wood rot. This is usually the result of wood being exposed to water due to improperly installed (or missing) flashing. When the moisture content in wood reaches 19%, wood rot (which is actually a fungus) goes to work. The damage, however, isn’t always visible at first – yet another reason to do an annual deck inspection!

  • Inspect several areas of your deck to ensure the wood is still sound, among them:

  • The ledger board - The ledger board is the piece of lumber that runs parallel to the edge of the house, attaching the deck to the house. Usually the first board installed, the ledger board supports one end of the deck joists and bears about one-half of the deck’s weight. The board must be the same material and size as the rest of the joists, and it is must be attached firmly – and with the correct fasteners – to avoid deck collapse.

  • Support posts and joists beneath the deck. It is normal to see some small cracks in the lumber, but large cracks may be cause for concern.

  • Deck boards, railing, and stairs – Even if they are structurally sound check for splintering wood as well, splinters hurt!

  • Look for small holes in the wood or evidence of sawdust/wood dust. If any are present, it may be an indication of insect infestation.

  • Examine any areas that are regularly exposed to water, tend to remain damp, or are in regular contact with fasteners. If you can easily penetrate the wood or if the wood is soft and spongy, you might have wood decay.


  • Proper installation of galvanized ledger board flashing is critical. In my experience the lack of a proper one is one of the most common reasons for premature deck failure.

  • Flashing works to prevent moisture and debris from collecting between the house and the ledger board.

  • Ensure that your flashing is installed behind the siding and over the top of the ledger board. Ideally an ice and water barrier should be installed underneath siding and between ledger board and building.

  • Flashing should run the entire length of the ledger board and be free of any nail or screw holes.

  • If you notice water collecting anywhere, add flashing or replace what’s already there.


Ledger boards should never be attached with nails – building code strictly prohibits this! Deck tension hardware (structural screws, bolts, or tension ties) should always be used – and in accordance with local building codes and construction best practices. Ledger boards can be retrofitted with carriage bolts, lag screws, or “LedgerLok” screws to insure they’re safely secured.

  • If you have wood decking, check for popped nails and pound them down or replace them.

  • Tighten any loose screws.

  • Replace rusted or corroded fasteners, as the corrosion can deteriorate any surrounding wood.


  • Deck railing is as much as safety issue as a style statement. In fact, more injuries result from rail failure than complete deck collapse.

  • Push on your railing to ensure it doesn’t “give” in any way. Most balusters are only attached with small nails, ensure they are securely in place so children can't fall through them.

  • Ensure your rail complies with local building codes. That means a rail height of 36” if your deck is over 30” above ground.

  • Measure the spacing between balusters. To prevent small children and pets from squeezing through, the distance between each baluster cannot exceed 4” for line sections and 4-3/8” for stairs.


  • All electrical outlets, appliances and features must be code-compliant, childproof (if you have children or young visitors), and in good condition.

  • If electrical cords are present on the deck, ensure they do not present a tripping hazard.

The bottom line: Safety first. Take the time to inspect your deck and make needed repairs, or contact a qualified contractor like us for help. No matter how well-built your deck, an annual check-up is always in order. We’d be happy to assess your deck to assure it’s safe for you and your family.

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