How to inspect a deck ledger board

A deck ledger board inspection means checking the board that attaches the deck to the house for three things: water getting behind it, rot in the ledger or the house framing it is fastened to, and fasteners that are missing, rusted or the wrong type. You can do the first look yourself in about twenty minutes from the yard and the basement. If you find a gap between the ledger and the house, soft wood, rust streaks or only nails holding it on, have the deck evaluated before the next heavy snow or the next party.

What the ledger does and why it fails

On an attached deck, one side of the frame is held up by posts and footings, and the other side hangs on the house. The ledger is a board bolted to the house's rim joist, the framing that runs around the edge of the floor system. The deck joists hang from the ledger, usually in metal hangers. Everything on that side of the deck, including snow, furniture and people, is carried through the ledger's fasteners into the house.

Ledgers fail for a handful of reasons, almost all involving water:

• No flashing, or flashing that failed. Rain and snowmelt run down the siding and get trapped between the ledger and the house, rotting both.
• Nails instead of bolts. Older decks were often nailed on. Nails can work loose or pull out under load.
• Fastened through siding or to the wrong material. A ledger fastened over siding, or to brick veneer, stone veneer or a chimney, is not properly connected to the house's structure.
• Rot in the house's rim joist. The ledger itself may look fine while the house framing behind it has softened.

In Saratoga County, snow makes this more serious. A deck holding a few feet of wet, packed snow is carrying a heavy load, and a ledger already weakened by rot has little margin left.

The inspection, step by step

From the yard and under the deck

Use a flashlight and a screwdriver. Look along the full length of the ledger.

1. Look for a gap. The ledger should be tight to the house. Any visible gap, or a gap that has grown since last year, is a warning.
2. Find the flashing. There should be metal or membrane flashing tucked behind the siding above the ledger and lapped over its top edge, so water runs over and away from it. If you see bare wood meeting siding with no flashing, water is probably getting in.
3. Check for water stains. Dark streaks on the foundation or siding below the ledger, or stains running down the face of the ledger, show where water has been traveling.
4. Probe the wood. Press the screwdriver into the ledger, especially near the bottom edge and around each fastener. It should feel firm.
5. Look at the fasteners. You should see bolts with washers or structural screws spaced along the ledger, usually in a staggered pattern. Rust streaks, heads that have corroded, or a row of nail heads only are all reasons for a professional look.
6. Check the hangers. Each joist should sit in a metal hanger with fasteners in all the holes. Look for heavy rust or joists that have dropped in their hangers.

From the basement

If the deck is attached next to a basement or crawlspace, look at the inside of the rim joist directly behind the ledger. Water stains, mold, soft wood or rusted bolt tips coming through are signs that water has been getting in from outside. It is also where you can confirm that the bolts actually pass through the rim joist and have nuts on the inside.

Warning signs that mean stop using the deck

Some findings call for keeping people off the deck until it has been looked at by a qualified contractor or engineer:

• The ledger has pulled away from the house, even slightly, or the gap is growing.
• The ledger or rim joist is soft enough that a screwdriver sinks in easily.
• The deck is attached only with nails.
• The ledger is attached to brick or stone veneer.
• Joists have dropped or twisted in their hangers.
• The deck moves or sways side to side when people walk on it.

These are structural problems, and the repair involves the house framing as well as the deck. It is not a job for a quick weekend fix.

How ledgers are done right today

Current practice under the New York State Residential Code, which follows the International Residential Code, is far more specific than it was a few decades ago. A properly built ledger is fastened directly to the house's rim joist after the siding is removed in that area, with through-bolts or approved structural screws in a set pattern. Flashing is installed behind the siding and over the ledger to shed water. Many decks also have lateral load connectors that tie the deck framing to the house floor framing so the deck cannot pull away sideways.

Where a solid connection to the house is not possible, for example over brick veneer or a cantilevered floor, a freestanding deck with its own beam and posts near the house is the usual solution. A ledger repair or replacement is structural work and typically needs a building permit; check with your town or city building department. Our post on building permits in Saratoga Springs covers how to ask.

Make it part of your yearly routine

Ledger problems develop slowly, then suddenly. A quick look every spring catches most of them early. Add it to the after-winter walk-around in our spring home inspection after winter, and to your longer-term list in our home maintenance schedule for upstate NY. Gutters overflowing above the deck are a common source of ledger rot, so if water is pouring onto the deck in a storm, read our guide to soffit and fascia repair as well.

If the ledger is only one of several problems, the deck may be near the end of its life. Our list of signs your deck needs to be replaced can help you decide between repair and rebuild.

Frequently asked questions

Can a deck ledger be replaced without rebuilding the whole deck?

Sometimes. If the joists, beams and footings are sound, the deck can be temporarily supported while the ledger and flashing are replaced and the rim joist is repaired. If rot has spread into the joist ends or the frame has other problems, rebuilding often makes more sense.

How often should I inspect my deck ledger?

Take a quick look every spring and after any winter with heavy snow. A closer inspection every few years, or whenever you restain, is a good habit. Look sooner if you notice the deck moving differently or new stains on the foundation.

Is it safe to shovel snow off my deck?

Removing heavy snow reduces the load on the deck, and on the ledger in particular. Use a plastic shovel and leave a thin layer rather than scraping to the boards. If you already suspect a ledger problem, keep traffic and snow load to a minimum until it is checked.

We inspect, repair and rebuild decks across Saratoga County, including ledger and flashing replacement on decks whose frames are worth keeping. Every project starts with a site visit and a written scope that shows what will be done in each phase. See our work on the decks, stairs and railings page.