Is Your Deck Safe?

Experts estimate that nearly 50 million residences in North America have decks and that up to 30 million of those decks are unsafe. Is your deck one of the safe ones?

Following are some tips to help you identify an unsafe deck. Please keep in mind that these notes should in no way be considered a substitute for a complete deck inspection by a professional who is specifically trained to inspect decks. If you have any questions, our experts at Buckeye Building Analysis are always happy to help. We can perform your deck inspection as a standalone service or as part of a whole-house inspection.

The components of a deck


Research by the North American Deck and Railing Association (NADRA) finds that deck failure occurs most often for one of four reasons: 1) poor connection where the ledger board attaches to the home, 2) incorrect or faulty hardware used to connect the deck’s components, 3) improper framing or rotted framing components, and 4) insufficient or improperly installed footing members.

Ledger Connection

Deck failures most often originate where the deck connects to the house. Too often, unqualified builders inadequately connect a deck to the primary home structure. The International Residential Code and the Ohio Residential Code have specific requirements with regard to how a deck can be attached to a residence. These requirements are put in place for your safety. Depending upon the application, the fasteners may be thru-bolts, expansion anchors, epoxy anchors or lag screws. Regardless which ledger fasteners are used, they must be at least 1/2″ in diameter. There should also be flashing and weatherproofing installed at the ledger to prevent damage to the ledger board and the home itself.

attachment-to-ledgerThese screws are not appropriate ledger fasteners in any jurisdiction

deck_collapse2This is the result when the ledger is not properly connected.

deck_collapse1A deck should never be attached to an overhang (this should have been a freestanding deck). Ironically, the only reason this home didn’t experience worse damage is because the ledger wasn’t properly attached

Incorrect or faulty hardware

Deck “hardware” includes fasteners (such as screws and bolts), and connectors (anchors, joist hangers, tension ties, etc.). Hardware can be inadequate in any number of ways, but most failures result from either the wrong hardware being used, the hardware being installed incorrectly, or the hardware being old and worn.

Correct deck hardware is designed to resist the corrosive effects of nature and to help support the load it is meant to support. Too often, we see decks built with undersized hardware, hardware that is meant for indoor use only, or fasteners that will quickly corrode when in contact with pressure-treated wood. Any of these issues should be cause for concern because they compromise the safety of the deck.

joist-hangerHere we have an incorrect connection (or lack of connection) of a joist. (In fact, all the joists on this deck were installed the same way, simply “floating” in the joist hangers, a very dangerous situation.)

Improper or rotted framing

It’s also important that the framing members of your deck are sound and installed correctly. If even only one framing member is defective, it could leave the entire deck structure vulnerable.

Keep in mind, too, that even a properly constructed deck cannot last forever. Due to a deck’s constant exposure to various weather conditions, a deck’s components will eventually wear out. When this happens, it’s time to replace the deck.

deck-post-to-beambeam_to_postRotted beam attached improperly.

Insufficient/incorrect footings

Frequently overlooked is a deck’s connection to the ground. Proper footings are required to maintain a deck’s stability. In colder climates like Ohio, this is most often caused by frost heave (movement that results when the ground freezes and thaws). To prevent heaving, a deck’s footings should extend below the frost line. While it is impossible to ascertain a footing’s depth from a simple visual inspection, you can monitor your deck for vertical movement between the cold and warm months. Shallow footings will cause your deck posts to rise in the spring and settle lower again in the winter.

deck-footingsfootingWhile the quality of below-grade footings can be difficult to determine by looking, it’s clear to see that this deck is not adequately supported.

Other things to look for

Any deck that rises 30 inches above grade needs a railing to protect you and your friends and loved ones from dangerous falls. The deck railing should be at least 36 inches tall, it should be strong enough to support 200 pounds of lateral force, and it should include a series of balusters less than 4 inches apart to prevent falls. The deck floor should also be at least 10 feet below any electrical service lines. All too often, a homeowner will build a deck at the back of their house, ignoring the fact that the deck has now put the overhead service lines well within reach (a sure sign that the homeowner didn’t get the proper permits and authorization before building the deck).

service-lines electrical-serviceWhen you can easily reach electrical service lines from a deck, that’s a clear indication that the deck was built without a permit (suggesting that there are probably other problems with these decks as well).

no-spindlesThe lack of balusters (spindles) on a raised deck is another good clue that the deck wasn’t properly permitted.

deck-joist-span-attacheddeck-overhangThere are specific requirements with regard to a deck overhang so we don’t end up with a deck that leans like this.

Bottom line

Decks are so popular across the U.S. because they provide an attractive outdoor space to entertain or to simply enjoy some quiet time alone with your preferred beverage. But every year, unfortunately, thousands of people are seriously injured by accidents on unsafe decks. This is why we suggest that you inspect your deck every year as part of your spring maintenance protocol. Then you can relax with the peace of mind that comes from knowing your deck is safe for your and your loved ones.