How a deck frame goes together

1) Cure footings and confirm bracket locations. 2) Install the ledger to the house rim with flashing. 3) Set posts in brackets, then the beam on post caps. 4) Hang joists from the ledger and seat them on the beam at 16″ O.C. 5) Install end-rim joists and mid-span blocking. 6) Inspect before decking goes on. The sequence ensures every joist has known bearing points before you cut it to length.

IRC R507.9 requires 1/2″ lag screws or through-bolts staggered top and bottom, spaced 16″ O.C. for the most common load conditions. The ledger bolts into the house rim joist — never just the sheathing. Flashing (R703.4) tucks behind the siding and over the top edge of the ledger to keep water out of the house. Z-flashing or self-adhered tape are typical. Drip-edge below directs water away from the band joist.

A doubled 2×10 beam (or doubled 2×12, depending on span) replaces a single member because two layers nail-laminated together carry roughly 2× the load of a single board the same width. Code-prescriptive deck beam tables in IRC R507.5 are all written for doubled members. Single 4×8 or 4×10 timbers also work but cost more and are harder to handle.

At the ledger: yes, always. Joist hangers (Simpson LUS210 or equivalent) transfer the joist's downward load into the ledger via the hanger's nailing flanges. On the beam: usually no — joists bear on top of the beam by gravity. Some configurations face-mount joists to the beam side instead (flush-beam framing); those require hangers on the beam too. R507.7 covers the hanger spec.

IRC R502.7 requires blocking between joists when the joist depth exceeds 12× the joist thickness — which means any 2×10 (9.25″ deep, 1.5″ thick, ratio 6.17) or 2×12 (11.25″ deep, ratio 7.5) is borderline but typically NOT mandatory. Where it IS required: spans over 8 ft and decks supporting hot tubs or other concentrated loads. Even when optional, blocking reduces bounce noticeably — most builders install it on any deck over 10 ft span.

Drop framing: joists sit on top of the beam by gravity. The deck top is one joist height + decking thick above the beam top. Most common for residential decks. Flush framing: joists hang from the beam via face-mount hangers — joist tops and beam top align, creating a thinner profile. Required when overhead clearance is tight (e.g., low door thresholds) but adds 20-30% labor cost from extra hangers and precise alignment.