Ledger — Attached Deck Support Board Guide for Homes

A ledger is a horizontal structural board bolted to a building to support one side of a deck or similar framed assembly.

Ledger diagram — labeled parts, dimensions, and installation context

What It Is

On a deck, the ledger transfers loads from the joists into the house structure. Because it is attached directly to the building, correct flashing, fastener spacing, and attachment into proper framing are critical to prevent water damage and structural failure.

Types

Most residential deck ledgers are pressure-treated dimensional lumber sized to match the deck framing depth. Engineered details may use steel ledger brackets or spacers, but the key distinction is between a properly flashed structural ledger and a nonstructural trim board that only looks similar.

Where It Is Used

Ledgers are used where an attached deck, porch landing, or stair platform meets the house. They are usually fastened through the sheathing into rim joists or other approved framing members, not just into siding or veneer.

How to Identify One

A deck ledger is the board running along the house directly under the deck joists or joist hangers. You may see bolts or structural screws, metal flashing above it, and joist hangers attached across its face.

Replacement

Ledger replacement is serious structural work and often requires partial deck removal. If there is rot, missing flashing, loose fasteners, or improper attachment, a licensed contractor should evaluate whether repair, reinforcement, or full rebuilding is needed.

Ledger — FAQ

Why is the deck ledger so important?

It supports one side of the deck and transfers load into the house framing. Ledger failures can cause partial or total deck collapse, which is why attachment details are heavily regulated by code.

What causes a deck ledger to fail?

Common causes include missing flashing, water rot, undersized or missing fasteners, and attachment into weak materials such as brick veneer or sheathing alone. Hidden decay behind the ledger is a major concern on older decks.

Can I replace a deck ledger myself?

This is usually not a casual DIY repair. The work affects structural support and water management at the house wall, so permits and professional design or inspection are often required.

How can I tell if my deck ledger has a problem?

Look for rot, rusted fasteners, loose guardrails near the house, visible movement, or staining at the wall connection. A qualified deck inspection is the safest way to assess hidden conditions.