How to Properly Install a Ledger Board – Following Building Codes ✅
When it comes to building or repairing a deck, the ledger board is one of the most critical components. This horizontal board attaches directly to your home and carries a large portion of the deck’s weight. If it’s not installed correctly and up to code, it can lead to structural failure, water intrusion, and costly damage to your siding and framing.
According to Washington State building codes, a ledger board must always be attached directly to the house’s structural framing, not just the siding. This requires removing the siding in the installation area, placing the ledger tight against the rim joist, and fastening it with structural lag bolts or code-approved ledger screws — never nails, which can pull out over time. Proper spacing (typically 16" O.C. or per code) ensures the load is evenly distributed.
Another essential step is flashing installation. A continuous strip of metal or PVC flashing must be placed over the top of the ledger board to prevent water from seeping behind it. Without flashing, water can infiltrate the wall system, leading to rot, mold, and compromised deck safety. Caulking alone is never enough — proper flashing is the only code-approved solution.
At MoDecks – Deck Builder Kirkland & Sammamish, we specialize in professional deck repair, refinishing, staining, and full rebuilds. Whether you need a ledger board replacement, a complete structural repair, or just a deck refinish.
