What is the average life expectancy of a wood deck?

Your deck is really no different than your home, in that, you want it to be built with the same quality and attention to safety, as well as, compliant with the Building Codes.

In Central North Carolina, it is common to see asphalt shingles protecting our dwellings. In most cases, these shingles carry a 25 or 30 year life expectancy. What is the average life expectancy of a wood deck? Even with routinely applying a sealing agent or a wood preservative to an exposed wood deck, most experts agree that the average life expectancy of a wood deck to be 10 to 15 years. That figure puts millions of wood decks in the U.S. on the other side of their useful life and may be possibly unsafe. 850 reported injuries and 20 deaths have occurred due to deck collapses since 1999.

Deck failure is a growing problem across our nation. It is estimated, of the forty million existing decks, roughly half need to be retro fitted or rebuilt. Whether you have an existing deck or you’re thinking of building a new one, it is important that you consult with a qualified licensed professional such as a Structural Engineer, a Licensed General Contractor or a Professional Licensed Home Inspector to insure your deck is structurally sound and safe.

According to the Simpson Strong Tie Company, there are five warning signs of an unsafe deck:

1. Rot-
Left exposed to the elements of nature, the structural integrity of the posts, beams and joists can be compromised and may no longer perform the function for which they were installed. This exposure may make your deck unstable.

2. Cracks-
It is common for cracks to develop as wood ages. Large cracks may lead to excessive cracking and can weaken the structural components of your deck, making it susceptible to collapse.

3. Rusty Nails or Fasteners-
Galvanized or not, many metal connectors, nails and even screws can corrode. Once a nail starts to rust, it weakens and any associated shear forces may cause the nail to work free or snap.

4. Loose Fastener Connections-
There is a significant amount of vibration on a deck not only from people and pets but from the wind and rain as well. A fastener, such as a nail will work free and rise. Have you ever stubbed your toe on a decking nail that’s not seated? Loose railings and wobbly staircases are an example of the effects of loose fasteners and these areas should be addressed or they may fail.

5. Missing Connections-
Your deck may be unsafe if your only means of attachment to your home is nails. You should see a combination of wood, bolts, nails (or screws) and metal connectors at the band attachment to your home. If all you see are nails, your deck may be at a high risk to collapse.

If you are a Real Estate Professional with existing home listings or you, as a home owner, are in the market to sell your home, the North Carolina Home Inspection Licensing Board is recommending decks be brought to the current (new construction) Building Code, specifically if the deck is nailed to the home with no other visible means of attachment. Nails can corrode and fail behind the deck band causing the deck top collapse. Unless it can be otherwise demonstrated that the deck attachment to the home is secure; the deck should be bolted to the home or directly supported from underneath.

The North Carolina Residential Building Code Chapter 5 states:

R502.2.1
Decks. Where supported by attachment to an exterior wall, decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads as applicable. Such attachment shall not be accomplished by the use of toenail or nails subject to withdrawal. Where positive connection to the primary structure cannot be verified during inspection, decks shall be self supporting.

As a Professional Licensed Home Inspector, when I inspect decks not only do I check for the 5 warning signs but I also put my Licensed General Contractor experience to use by evaluating the three types of forces that put pressure on your deck:
• Uplift- which is the lifting upward pressure effect caused by the wind pushing your deck upwards from underneath.
• Horizontal- the lateral movement side to side caused by people walking on the deck and leaning on the rails.
• Downward- the simple gravity of people standing on the deck as well as furniture snow and ice.
I also evaluate the continuous load path. The continuous point load path is the transfer of weight from the top, through the deck, to the post and down to the footings.
Hiring the right professional is vital. A Qualified Structural Engineer, a Licensed General Contractor or a Professional Licensed Home Inspector all should be able to evaluate the means of attachment and the condition of your deck. It is my recommendation to have your deck or screen porch professionally evaluated. A regular maintenance routine, as well as, educating yourself on the warning signs and knowing the steps to a stronger, safer deck will help ensure your deck is structurally sound and properly maintained.

About Chad D. Collins:
A licensed general contractor since 1997, custom home builder Chad D. Collins has been transforming clients' dreams into elegant, homes while building a reputation for skilled craftsmanship. Chad's commitment to excellence has earned Collins numerous top industry awards, including the coveted Triangle Sales and Marketing Council's MAME Building Company of the Year in 2007 and 2008. To learn more about Chad please visit www.collins-design-build.com