Proper ledger attachment requires: (1) removing the siding at the ledger location to expose the sheathing and rim joist; (2) installing continuous Z-flashing or self-adhering membrane over the top of the ledger with positive drainage to the exterior — this is the element most commonly skipped; (3) fastening the ledger to the structural rim or band joist with 1/2-inch diameter lag screws or through-bolts per IRC Table R507.2.3, properly staggered — not fastened to sheathing and not with nails; (4) reinstating the siding with a proper gap at the ledger. Missing or inadequate flashing allows moisture to enter behind the ledger and deteriorate the house rim joist — a process that happens invisibly over years and produces either a structural failure or an expensive remediation when discovered during a sale inspection. Ledger flashing is the most commonly deficient deck detail in Utah and the one with the most expensive consequences when done incorrectly.