Deck collapses are big news. My Google news feed brings in about four reports a week this time of year. Often there are injuries; very rarely there are fatalities. Of course, this is terrible stuff, both in terms of human suffering and its effect on our industry. One result of the number of deck collapses in the news is ever-tightening deck codes. For example, since 2009, the IRC has required either lateral-attachment hardware or an engineered alternative. In the 2012 IRC, the ledger bolting locations have been codified to practically eliminate the possibility of stepping a deck down from the house (technically, what’s in the 2012 IRC has been in the IRC by reference for a long time, but universally ignored).
However, as far as I can determine, we have only anecdotal evidence of why most deck collapses happen. There is no forensic meta-study of the causes of deck failure. The closest I can find is a Legacy Services report from 2010 (Legacy Services is owned by Michael Beaudry, the executive director of NADRA), which states: “Based on the statistics from the CPSC (Consumer Products Safety Commission), 224,000 people were injured nationally due to a deck or porch over the study period [2003 to 2007]. Nearly 15 percent of these injuries were a result of a structural failure or collapse.” That’s an annual rate of 672 injuries due to deck failures. To provide some perspective of the overall risk: The CDC reports that approximately 44,000 Americans died in car crashes in 2007.
I’ve looked at the CPSC reports the Legacy Services report is based on. They don’t state the cause of any deck or railing collapse. That’s because the CPSC reports come from notes made by ER personnel, not building inspectors or forensic engineers. There is no nationwide reporting system to provide this data. In short, we have no overarching idea — based on the CPSC reports, the Legacy Services report, or any other report I’m aware of — of why decks fail.
The Legacy Services report is oft-quoted to call for annual deck inspections, which I’m all in favor of. My concern is that the report, as well as news stories, drives tighter codes when there’s little evidence that the codes in force prior to 2009 were inadequate. So, while I don’t know that tighter codes solve any real problem, I do know that they cost a fair amount of money, which makes it harder for legitimate contractors to win bids against the so-called Chucks-in-a-truck. Does Chuck bother with a building permit or with codes at all? Maybe. Or not. How about the DIY homeowner who thinks you’re both too expensive?
Circling back to my Google news feed, one common thread is that many of these collapsed decks are older. I’ve been around long enough to remember when carpenters and even some building officials had the attitude of, “It’s only a deck.” And the point isn’t that a deck becomes unsafe simply because of its age — with proper initial construction and good maintenance, the often quoted 15-year lifespan of a typical deck is conservative. The point is that because of the it’s-only-a-deck attitude, older decks don’t tend to be built as well as what you folks build today.
News stories rarely cite a cause for a deck failure. When a cause is mentioned, it’s usually that the ledger was attached only with nails. I’ve also seen news photos where the house’s band joist had rotted away as the result of an unflashed deck ledger, and several cases where the ledger attached to a cantilever. These are all long-standing code violations, but fairly common situations in both older decks and in unpermitted decks. Tighter codes wouldn’t have helped these decks that weren’t built to code in the first place. And I have yet to hear of an epidemic of properly bolted and flashed decks falling off houses. Given the huge number of unpermitted decks and decks older than 15 years or so, it’s hard to conclude that decks built to the pre-2009 code by professionals are even a small part of this problem. But it’s these same pros who will follow the tighter codes, and whose bid prices will increase, making it ever more attractive for customers to bypass the codes entirely by building without permits. And that definitely will increase the likelihood of future deck failures.