How to Install a Ledger Board

Advanced Level

Attach a deck ledger to a house: siding removal, flashing, fastener sizing, bolt spacing, waterproofing.

Materials Needed

Note

Use 1/2" lag screws or through-bolts per IRC. Never nails, deck screws, or non-specified fasteners.

Note

Ledgers cannot attach through foam insulation thicker than 1". Use stand-off systems for deeper foam.

Step 1: Prepare the Wall

Remove siding to expose sheathing. Ledger bears against structural sheathing, NOT siding. Cut back siding 2" beyond ledger for flashing.

Step 2: Flash the Band Joist

Apply self-adhered membrane from 4" above ledger top to below ledger bottom. This is the critical waterproofing detail.

Step 3: Fasten Per Code

Bore holes per IRC Table R507.9.1.3(1). Staggered pattern. Seal each hole before inserting lag. Install Z-flashing at top tucked behind WRB.