If you aren’t familiar with the new lateral attachment requirement for decks in the 2009 IRC, you should read this issue’s Structure department (see page 24) before reading on here. Working with contributing editor Glenn Mathewson on that Structure piece convinced me that this new provision is ill considered and was likely rushed into the code because of the recent press given to deck collapses. I know the International Code Council folks work hard and lateral attachment is important — no one wants decks to fall off houses. But the detail shown in the code is not appropriate in all cases, and as written, it’s not even clear when it’s actually a requirement. However, I’ll bet my first-born son that a lot of jurisdictions will treat that detail as a requirement for all decks.
The new attachment detail isn’t a big deal to install in houses with easy access to the floor structure and where the floor joists run perpendicular to the ledger. But when the floor joists are concealed by a finished ceiling, you’ll have to be good at drywall repair and interior painting because you’re going to be opening up that ceiling. And what about attaching a deck to a house where the floor joists run parallel to the band joist? Mathewson describes a detail that he and ICC staff worked out. But because it’s not in the code, some jurisdictions will require engineering. And the attachment requirement is the same whether the deck is 15 feet in the air or 8 inches off the ground — where the main risk during a deck collapse would be to the petunias planted alongside.
On the flip side, some mongo-sized decks with ledgers composed of three or more pieces will be built using only the two specified hold-downs. Hey — it meets code. And how many decks will be built without permits because a contractor or homeowner decided that figuring out an unusual lateral attachment situation was beyond them? The IRC doesn’t even provide specific lateral loading requirements to ease design, as it does with floors, roofs, and guards. Even engineers might be left guessing just what the parameters are. The code should provide additional solutions, such as those Mathewson describes in this issue, or as Fairfax County, Va., provides (fairfaxcounty.gov/dpwes/publications/decks/details.pdf).
I could go on, but it would just be a rant about people jumping behind a good idea without considering the unintended consequences. And I know someone reading this is thinking, “So what? It’s worth it if it saves one life.” Well, if that argument held true, the national speed limit would be 5 mph. We make nuanced decisions about safety all the time.
And really, poorly considered code changes are no one’s fault but our own. Who reading this spoke up during the public comment period for the 2009 IRC? Indeed, who pays any attention to the code modification process until something new hits them in the wallet? It’s not entirely too late, though. New building codes don’t become law until adopted by the local jurisdictions. If you agree that this new requirement has issues, get in touch with whoever is in charge of code adoption where you live and let them know what you think.