Ledger Board

Choosing A Free-Standing Or A Ledger Board Deck

In terms of the deck's overall design, one of the most important decisions deck builders must make is whether to attach their deck to the house using a ledger board or whether to build an unattached "free-standing" deck. Decks built using a ledger board have the advantage of not requiring an additional support beam and related footings running next to the house - to support the ends of the floor joists closest to the house. Additionally, attached decks require less bracing. On the other hand, not all homes will allow attaching a ledger board due to the exterior surface and/or the shape of the home's exterior wall.

Important: Make sure to take the time to learn how to install your ledger board properly. Unlike other parts of the deck, if something goes wrong with the ledger board, the results could be catastrophic. Even with a securely attached ledger board if there is even a small water leak, it's going to be very tough to make repairs. The ledger board can't be removed without disassembling the entire deck. When it comes to the ledger board, get it right the first time.

Free-Standing - Deck Not Attached: Not all decks can be attached to the house. The surface of the old stone home shown is too irregular to bolt on a ledger. Notice how freestanding decks must use at least two support beams (whereas attaching the deck to the house with a ledger board eliminates the closest beam). When designing a free-standing deck, it's always best to cantilever the deck's floor joists as much as possible on the ends closest to the house. In so doing, the footings for the support beam closest to the house are placed as far away as is possible from the home's foundation. This is important since the backfill around homes can take many, many years to settle. (Backfill is the soil used to fill in the hole around the home's foundation when the house was built.)

Check Point - It's not unusual for do-it-yourself builders to look for shortcuts. One area where it's important not to take a shortcut is the proper installation of water-proofing flashing. The amount of grief and expense even the smallest water leak can cause is considerable. It only takes a pinhole for water to seep in and create the perfect conditions for wood decay fungi to grow. For a nominal fee, consider getting a password and learn how to keep destructive fungi and wood loving insects away.

The end band joist that caps off the ends of the deck's floor joists is spaced away from the house about 3/4" and is attached by toe-screwing 3" long deck screws. Joist hangers are not needed. Alternatively, you may use solid blocking the same size as the deck's floor joists and nail them in-between the ends of the floor joists. Notice how the rim joist running along the side of the deck laps over the end of the board that caps off the deck's joist ends and is nailed in place with three 16d nails. Although not necessary, it's good insurance to reinforce the corner connections with a 90° reinforcing angle as shown.

Ledger Board - Deck Attached: When a deck is attached to the house, a ledger board is bolted to the side of the house. To keep water out, metal flashing is carefully installed behind and on top of the ledger board (flashing is not shown). The ledger board itself is 0.40 treated lumber and is chosen for straightness. The rim joist running along the side of the deck laps over the end of the ledger board and is nailed in place with three 16d nails. Although not essential, it's good insurance to reinforce the corner connection with a 90° reinforcing angle as shown. To prevent puncturing the metal flashing underneath the ledger, special 1-1/2" long 10d double hot-dipped zinc coated joist hanger nails are used to attach the reinforcing angle and joist hangers.

Always use the nail size specified for your hanger. When you're picking your metal connectors out of the parts-bin at the building supply store, make sure to jot down the required nail size and nailing pattern. In the case of attaching hangers to a ledger board, we don't want the nails poking through and damaging the metal flashing behind, so shorter special 10d hanger nails may be used with a load reduction of 0.77 - the load reduction is required when switching from full length 3" long 10d nails to the shorter 1-1/2" long special 10d hanger nails. BestDeckSite automatically factors in a load reduction for shorter nail lengths in the hanger recommendations. Additionally, there will often be more than one joist hanger height available at building supply stores for a given floor joist size. As a matter of course, always select the tallest joist hanger available since it will use more nails and consequently, be stronger.

Check Point - Several factors need to be considered when sizing ledger board bolts. Lag bolts have a much lower capacity than hex-head machine bolts. If the ledger board has a high moisture content at the time of installation, the capacity of the bolts is further reduced. Additionally, the type and thickness of the lumber effects the capacity of your deck bolts. The connection of the ledger board to the house, and the bolted-connection of beams to posts, are critical. When these connections fail, they often do so suddenly when the deck or gazebo has lots of people on board. The bolt size, type, diameter, and length, as well as, the joist length, and design loads need to be considered. Get a password and learn how to make bolted-connections that will keep everyone safe.

Important: ACQ treated lumber is very corrosive of hardware, connectors, and flashing. This is due to the high amount of copper in the ACQ preservative used to treat the wood. For brackets, strapping, hangers, bolts, screws and all other metal hardware and connectors, the minimum recommendation has been upgraded from G185 hot-dipped galvanized steel to stainless steel or specialty fasteners with coatings specially designed to be ACQ corrosion resistant. Regardless of the thickness of the coating, galvanized steel and coated aluminum should not be used when in contact with ACQ treated lumber.

The content under the "How-To" menu is a small sampling of all the material covered on BestDeckSite. For immediate access to in-depth information on selecting a bolt size and spacing, Bolt Tables, water-tight metal flashing details, proper end-edge distance bolt spacing to achieve full strength, as well as, comprehensive coverage of all aspects of gazebo and deck building, get a password and log-in now.

     Ledger Board

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