Attaching a Deck
I’m designing a deck off a house whose floor joists are perpendicular to where the deck joists will run. I’m concerned that tying the deck into the rim board will put an excessive load on it. Would it be better to build a freestanding deck by adding another support beam, posts, and piers up close to the house?
Lisa Marie London, via Facebook, None
Editorial adviser Mike Guertin replies: The deck ledger can be connected to the rim board on the side of the house where the house joists run parallel to the rim board and perpendicular to the deck joists. There’s no need to install another set of footings and another beam to support the deck at the house side—unless you prefer that method.
To attach the ledger to the house, you can use 1/2-in. lag screws or 1/2-in. lag bolts, following the IRC’s (2009-2015) prescriptive fastener schedule. You also can use proprietary structural screws such as Fasten Master’s LedgerLoks, Simpson Strong-Tie’s SDWS or SDWH screws, or GRK’s RSS screws, following their fastener schedules. In addition to securing the ledger using bolts or screws, install at least two lateral-load connectors between the deck joists and the house’s floor framing. If you follow the IRC’s design for lateral-load connections, you’ll need to install joist-depth blocks between the rim board and the first floor joist and between the first and second floor joists. Framing angles such as Simpson Strong-Tie’s A35 can be used to attach the blocking. Blocking provides anchor points for attaching tension-tie lateral-load connectors, which can be either Screw Products’ DeckLok, Simpson Strong-Tie’s DTT2Z, or USP’s DTB-TZ. (Simpson’s DTT1Z lateral-load connectors can’t be used where the house joists run parallel to the rim board.)
From Fine Homebuilding #256, pp. 82, November 11, 2015