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4 Warning Signs of an Unsafe Deck

Often perched over hills or raised up for views, decks can be dangerous places if they weren’t properly constructed or are in disrepair.

Unfortunately, “When a deck reveals it has a problem is often when it has the most people on it,” says Tim Brown, owner of PHI Decks. “We see two or three of these incidents a year.”

In fact, 224,000 people were injured nationally due to a deck or porch between 2003 and 2007. Of those injuries, 33,000 were a result of a structural failure or collapse, according to the Consumer Product Safety Commission, which offers one of the few studies on deck collapse.

The CPSC estimates there are more than 40 million existing decks in the U.S. and more than 20 million decks and porches are older than 15 years — well beyond their average lifespan. In addition, many of those decks were constructed prior to 2009, before true deck codes existed, Brown says.

That’s why along with constructing decks, builders also need to know how to determine whether to repair or replace — and what to look for to make that final judgment.

Here are three major warning signs that a deck may be unsafe:

1. Heaved or dropped footings. Either one of these issues can cause a deck to become uneven and unstable. Heaving typically happens from freeze/thaw conditions. Dropping is often the result of footings being poured on disturbed soil, such as backfill. “Both of those are tell tale signs that something needs to be done,” Brown says. Sometimes, those issues can be repaired, but often, they’re a sign replacement is in order.

2. Missing or corroded metal connectors. The International Residential Code requires metal connectors at key places: ledger to structure; post to beam, joist to beam and joist to ledger, Brown says. If those are missing, often connections are simply toenailed together. If, and when, the wood rots, nailed connections will not hold. But metal connections maintain their support better even if rot occurs. Replace any rusted connectors to avoid wood deterioration.

3. Improperly flashed ledger board: Flashing prevents moisture and debris from collecting between the structure and the deck’s ledger board — and rot. If flashing is missing, use an ice pick or screwdriver to test the wood. If it’s easily penetrated ¼ inch to ½ inch, or the wood is soft and spongy, it’s likely time to replace — and an indicator the whole deck may be in need of attention, according to the North American Deck and Railing Association.

4. Inadequate railings. If the railing can be moved more than an inch or two at the top, it’s an indication that it’s time for replacement, Brown says. He also consults the International Residential Code for deck rails, which requires any deck more than 30 inches above the ground to have a guardrail, though any deck with a guardrail must follow code. The IRC also requires that rails be a minimum height of 36 inches above deck surface. Stair rails must be 34 to 38 inches above the nosing of the stair. And the maximum space allowed between balusters is 4 inches. For homes with the right aesthetic and view, Brown’s go-to replacement is cable railing because it’s strong and maintains views. “It’s a great finished look and it stands the test of time,” he adds.

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