ledger
A board attached to a wall to provide support for attaching other structural elements (such as deck joists or roof rafters) to a building.
ledger: the load-bearing board that ties structure to wall
A ledger is a horizontal board fastened directly to the exterior wall of a building to carry the weight of attached structural members, most commonly deck joists or roof rafters. It serves as the bearing point where another structure meets the primary building, transferring loads into the existing framing rather than relying on ground support alone.
Ledgers are typically 2-inch nominal lumber (1.5 inches actual thickness), most often pressure-treated 2x8, 2x10, or 2x12 depending on the span and load being carried. The board is lag-bolted or screwed through the rim joist or band board of the house, and fasteners must penetrate into the solid rim joist or into the house band board, never into siding or brick veneer alone. Building codes specify fastener spacing, typically 16 inches on center, with washers to prevent pullthrough.
Common failures and why they matter
Ledger failure is one of the leading causes of deck collapse. Water trapped between the ledger and the wall causes the wood to rot and the connection to weaken. A flashing detail is essential: a metal drip edge installed above the ledger diverts water outward and prevents saturation. Many failed ledgers were installed with no flashing or with siding left in place behind the ledger, allowing moisture to accumulate in the cavity. Once rot begins in the rim joist, both the ledger and the house frame are compromised.
The ledger works in tension and shear, pulling the house frame toward the attached structure. Fasteners must resist both upward pull and lateral shift. Under code, deck ledgers are treated as critical connections; undersized bolts or incorrect spacing can allow creeping separation or sudden failure under load. Snow load on a roof deck or multiple people on a deck platform creates significant downward force that the ledger must anchor safely.
Installation quality varies widely. Residential ledgers are frequent trouble points because they are sometimes installed by non-professionals or treated as afterthought additions. A properly installed ledger requires removal of siding, installation of flashing before the ledger goes on, fastening into rim joist (not into the band board veneer), and sealing the flashing top with sealant. Without this discipline, the connection fails within years, not decades.