Deck Failure - What Every Homeowner Should Know
Earlier this month the local news reported a deck failure in Salvo in which 3 people were hospitalized. Last year, there were two such incidents to the south at Emerald Isle. According to the Consumer Product Safety Commission, there were 33,000 injuries as the direct result of deck failure from 2003 to 2015. Even more alarming, is that these incidents are increasing at a rate of 21% per year. Most homes have decks, but on the Outer Banks it is common to see two or three stories of decks on a beach house.
Why do most decks fail and what should you look for when evaluating the condition of your deck? Let’s start with the components of a deck:
- Band Board: the section of the house where the deck is directly bolted. Usually a 2x10 or 2x12 framing member.
- Ledger Board: a primary deck board that is bolted through the band board.
- Deck Joists: members that support the deck boards.
- Railing Posts: usually 4x4 posts that provide lateral support for the safety railing.
- Railing: provides fall protection.
- Stringers: the support beams for stairs and stair railing.
The most common cause of deck failure is at the deck railing. Inadequately fastened railings (i.e. rusty nails/screws) are usually unable to withstand much lateral load. Low railings are also a cause for concern. If a person were to stumble or fall into a railing, not only should it be able to withstand the load, but it should be high enough that a person would not tumble over the railing.
The North Carolina Residential Building Code requires deck rails to be at least 36” high and able to support 200 lbs. However, a height of only 36” puts the top of the rail lower than the center of gravity for most people 5’-6” or taller. Furthermore, the National Center for Health Statistics claims that over 3.8 million people in the United States are over 300 lbs. The point is this: the building code dictates only the minimal standard and it doesn’t hurt to be more proactive in your deck design.
Support posts and joists are another common reason for deck failure. Posts need to be sized correctly, post foundations or pilings need to be installed to the proper depth, and joists need to be attached correctly.
Failure at the ledger boards or stringers can also be catastrophic. Ledger boards need to be bolted through the band boards. An incorrectly attached ledger board can cause the entire deck to pull away from the house. An incorrectly attached stair stringer can result in the stairs separating from the decks.
Poor design is another leading cause of deck failure. Decks should be designed in accordance with the building code, especially in coastal and high-wind zones.
All homeowners should take the time to inspect their decks regularly. A registered professional engineer, home inspector, or licensed general contractor can help. The North American Deck and Railing Association (NADRA) has a Deck Evaluation Checklist available on their website. Some of the items that should be included in any deck safety check include checking for split or decaying wood (especially on structural members), check the stair stringers for cracks and loose railings, inspect all fasteners and connection points looking for nails that have backed out or rusted, make sure your deck flashing is in place and functioning, and check all railings and handrails.
The number of recent deck failures resulting in serious injury and costly claims has most certainly raised awareness about the required maintenance and inspection of decks as well as code enforcement. The truth is that most decks that are 20 years or older, were not subject to any kind of code enforcement or inspection at the time they were built. If you are in doubt about the safety of your deck, don’t hesitate to call a licensed general contractor, home inspector, or professional engineer.
By Matt Brauer, President of Beach Construction Group
A Licensed General Contractor
