Cut Your Boards:
Cut all of your boards according to the cut list. A circular saw, chop saw, or compound miter saw is recommended for cutting.
Build Seat Frame:
To make the seat part of this sofa, we are basically going to frame up a mini floor. Just attach 5 of the 25-1/2” long 2x4s to 2 of the 72” long 2x4s, spacing about 16” apart. Use 2-1/2” exterior decking screws. This completes the seat frame.
Attach arm rests (28-½” long) to legs (25-½” long) with 2-½” exterior decking screws. Build two arms.
Attach another 25-½” long board to the center of the arm, 14” up from bottom, with 2-½” exterior decking screws.
To finish the arms, add another 25-½” long board underneath the arm middle. We’ll use this board to tie into the seat framing in the next step.
Attaching Arms to Seat:
Attach the seat framing to the arms with 2-1/2” exterior screws, through the arm tie-in boards.
Attach seat slats to seat support frame, with 2-½” exterior decking screws.
Attach the final 72” long 2x4 board to the tops of the arms, at the back. This time use a pocket hole jig set for 1-½” thick boards, and 2-½” long pocket hole screws.