How to Install a Ledger
A ledger is a joist attached to the framing of the house. It carries the weight of the deck and transfers it to the foundation of the house. If you are installing an attached deck, your layout and installation will begin with a ledger. If you are building a freestanding deck, it will be supported on all sides by posts and footings, and you should skip to the next step.
Because the ledger functions as the first step in laying out an attached deck, you must position it precisely — level and firmly attached to the framing of the house. This means that the lag screws that fasten a ledger to a frame structure need to go through the sheathing and penetrate the band joist or studs. On brick, block, or concrete, use heavy-duty masonry anchors drilled into the masonry.
Cut your ledger from the same size lumber as your joists — 3 inches shorter than the width of the deck so you can attach the end joists to the ends of the ledger. In most cases you will have to remove siding to install the ledger.
What You Need
- Tape measure
- Chalk line
- Speed square
- Circular saw
- 4-foot level
- Cordless drill
- Tin snips for metal siding
- Caulk gun
- Socket wrench and sockets
- 2x lumber
- Felt paper
Fasten a Ledger: Optional Ledger Attachment
Some localities allow ledgers to be installed on the surface of the siding. This installation requires shims to keep the surface of the ledger vertical. Cut shims from siding stock and tack them upside down on your ledger location. Drill pilot holes and fasten the ledger to the rim joist with lag screws.
If your local code requires that the ledger be held away from the siding so it can dry out quickly, attach the ledger temporarily and drill all the pilot holes. Remove the ledger, push the lag screws through the holes, and slip on four or five washers behind the ledger. Drive the screws into the pilot holes.
Step 1: Mark and Cut Ledger
Mark the ledger outline by holding the cut ledger in place or by using a straightedge. Extend the marks 1-1/2 inches on both ends for the end joists. Set your saw to cut the siding, not the sheathing, and cut to the corners. Chisel out wood corners; cut metal corners with snips.
Step 2: Install Flashing
Replace damaged waterproofing on the sheathing with 30-pound felt paper. Cut metal Z-flashing or roll flashing to the length of the cutout and slide it at least 1 inch under the siding above the cutout.
Step 3: Install Ledger
Mark the ledger (and the header joist) for joist locations. If you're working alone, prop 2x4 braces at either end of the cutout and hoist the ledger in place, resting it on the braces. Center the ledger in the cutout, leaving 1-1/2 inches on either side for the end joists. Adjust the brace on one end to position the ledger exactly at the correct height and tack this end to the sheathing with a 10d nail or deck screw. Level the board and tack the other end.
Step 4: Secure Ledger
Counterbore lag-screw locations that fall on joist markings, then drill pilot holes for the lag screws through the ledger and about 1/2 inch into the band joist or studs (on a deck above the band joist). Drive washered lag screws into the framing with a socket wrench, stopping just when the screw won't turn without excessive force. Caulk counterbored holes, the joint above the flashing, and the bottom of the ledger. Don't caulk the ends yet.
What if the Ledger Anchors to Brick, Block, or Concrete?
Step 1: Drill Locator Holes
Drill the ledger for lag screw pilot holes. Then use masonry screws or braces to hold it firmly in place while you drill locator holes with a small masonry bit.
Step 2: Drill Holes
Remove the ledger. Drill holes using a masonry bit the correct size for the masonry anchors. Drill at least 1/4 inch deeper than the length of the anchors and blow out any dust.
Step 3: Install Anchors
Tap masonry anchors into the holes until they are flush or slightly recessed.
Step 4: Install Ledger and Flashing
Brace the ledger and drive the screws into the anchors. Tack a guide to the ledger. With a masonry blade, cut a kerf 3/8 inch deep for the flashing. Install and caulk the flashing.