How to Build a Ledger Board for a Soffit

Locate the wall studs on the wall with a stud finder, if you have a wood frame with siding. Mark the centers of each stud with a pencil. Omit this if you have brick siding.

Measure from the bottom of the fascia board to the wall with a tape measure, if your soffit is mounting to the bottom of the fascia board. If you're using a fascia board with a slot on the back for the soffit, measure from the back of the fascia board to the wall.

Cut a piece of 1-by-4-inch board to the measurement with a circular saw. Hold the board between the fascia board and wall, with the top of the board at the point where the soffit attaches to the fascia board.

Place a level across the board, and move the end of the board on the wall up or down as necessary until it is level. Make a mark on the wall at the bottom of the board with a pencil. Repeat the process every 6 feet down the length of the wall.

Have a helper to hold the end of a chalk line against one end of the wall at the board mark. Stretch the chalk line to the other end of the wall, aligning the line at your board mark. Hold the chalk line tight and snap a line across the wall. The bottom of the ledger board is installed at the chalk line.

Drill two holes on top of each other at each end of an 8-foot, 2-by-4-inch board with a 3/16-inch drill bit. This is part of your ledger board. Hold the board against the wall with the bottom edge of the board at the chalk line.

Drive 16d nails through the pilot holes and into the wall studs with a hammer. Measure from the opposite end of the wall to the end of the first ledger board. Cut the second ledger board to that measurement. Drill pilot holes as you did the first one. Install the board against the wall, butting the ends of each ledger board together.

Nail the ledger board to each of the wall studs along the wall. Use a caulking gun to apply a bead of silicone caulk along the top seam where the board meets the wall.