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Home / Code Guides / Deck Ledger

Deck Ledger Attachment — Bolt Schedule, Flashing & Lateral Load

Most deck failures are ledger failures. The IRC treats ledger attachment with a prescriptive fastener schedule, mandatory flashing, and a short list of surfaces you may never attach to.

RequirementModel Code StandardSection
Fastener schedule1/2-in. lag screws or bolts spaced per Table R507.9.1.3(1), based on joist span — staggered in two rows with prescribed edge distancesIRC R507.9.1.3
Ledger materialMinimum 2×8 pressure-preservative-treated lumber attached to a 2-in. nominal band joist or approved engineered rim boardIRC R507.9.1.1, R507.9.1.2
FlashingCorrosion-resistant flashing required over the ledger, preventing water intrusion into the band joistIRC R703.4, R507.9.1.4
Prohibited attachmentsLedgers may not be supported on stone or masonry veneer, and attachment to cantilevered floor overhangs requires engineeringIRC R507.9.1.1
Lateral load connectionDeck-to-house lateral connections: either two 1,500-lb hold-down tension devices or four 750-lb connections per the prescriptive optionsIRC R507.9.2
Fastener corrosionHot-dipped galvanized or stainless fasteners and hangers required in contact with preservative-treated lumberIRC R317.3

Worth knowing

  • Nails alone are never an approved ledger attachment for the vertical load path.
  • Attaching through more than 1 in. of exterior sheathing/siding stack-up reduces lag screw capacity and may require engineered fasteners.
  • When the house band joist can’t be verified (or is I-joist without a rated rim board), build the deck free-standing.
  • Many jurisdictions ask for the ledger fastener layout on the permit drawing — photograph it before decking goes down.
Sections cite the 2021 International Residential Code and 2023 National Electrical Code as model standards. This is BuildSpec’s own summary — not ICC or NFPA text; read the authoritative language at codes.iccsafe.org. Your state may be on a different edition with amendments — check your jurisdiction page or get an Address Report.
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