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How must a deck ledger be attached to the house?

Short answer. With 1/2-inch lag screws or through-bolts at the specified spacing, under IRC R507.9.1.3. Nails are never acceptable, and improperly attached ledgers are a leading cause of deck collapses.

  • IRC R507.9.1.3

Work it through

You're the contractor. Pick what you'd do, then see how each choice plays out.

Inspector Williams

County building inspector

During your deck build, Inspector Williams questions your ledger board connection to the house.

"I don't see lag bolts or through-bolts. Are you using nails to attach the ledger to the band joist?"

He's looking very serious.

  1. Correct

    Deck ledger attachment is one of the most safety-critical connections in residential construction. The IRC specifically requires 1/2" lag screws or through-bolts at specified spacing for ledger-to-band joist connections. Nails are NEVER acceptable for ledger attachment. Improperly attached ledgers are the #1 cause of deck collapses, which cause an estimated 30+ injuries and several deaths annually. Fix it. This is life-safety.

  2. Wrong and dangerous

    No nail, regardless of rating, meets the IRC requirement for ledger attachment. IRC R507.9.1.3 specifies lag screws or bolts. Arguing with the inspector about a life-safety connection marks you as either ignorant of a fundamental code requirement or willfully non-compliant. Deck collapses from improper ledger connections kill people. This is not a matter of opinion or construction practice — it's a specific, unambiguous code requirement.

All 26 permits, inspections & building codes questions

  1. Who is responsible for permits on a Maryland home improvement job?
  2. Can you skip permits if the homeowner asks you to?
  3. How do you build permit costs into a contract?
  4. Which home projects need a permit in Maryland?
  5. Do cosmetic bathroom refreshes in rentals need permits?
  6. What happens when an inspector finds work without a permit?
  7. What is your liability when unpermitted work fails?
  8. How should you handle a problem the inspector finds?
  9. Why do building inspections happen in stages?
  10. How do you get a building permit approved faster?
  11. Where is fire blocking required under IRC R302.11?
  12. When does a basement bedroom need an egress window?
  13. Where are smoke alarms required after a renovation?
  14. Can a homeowner refuse GFCI outlets in the kitchen?
  15. When does a deck stairway need a handrail?
  16. Does a bathroom need an exhaust fan under the IRC?
  17. How must a deck ledger be attached to the house?
  18. How is energy code compliance checked on an addition?
  19. Does the ADA apply to a single-family bathroom remodel?
  20. When does a retaining wall need an engineered design?
  21. What is required before removing a load-bearing wall?
  22. Can you build a deck over a utility easement?
  23. When does a patio trigger stormwater management in Maryland?
  24. Does a building permit override HOA approval?
  25. How do you take over a job another contractor abandoned?
  26. How do you assess a homeowner's failed DIY renovation?