The arbor bench has four main sections: the two sides, the bench seat, and the backrest. Build it in the sequence that follows, allowing for the inevitable variation in the thickness of the lumber and lattice, which will affect widths and lengths. The trellis top, which consists of two pairs of horizontal 2-by-6s and seven 2-by-3 crosspieces, is added piece by piece. Before starting construction, rip two of the 8-foot 2-by-6s in half (to create 2-by-3s).
Assembling the side sections
1. Cut the 4-by-4s 84 inches long. To avoid splintering, bevel the bottom edges of each post.
2. Divide the posts into pairs and mark them (A and B, C and D). Lay each pair side by side on a flat work surface. Measuring from the bottom end, mark points at 6, 7 1/2, 70 1/2, and 72 inches. Using a pencil and combination square, draw lines at these points across the width of the posts. Set blade of circular saw to extend 1/4 inch and make multiple passes to remove the wood between the pairs of lines, creating grooves.
3. Measure actual width of lattice panels, add 1/2 inch to that dimension, then cut four 2-by-4 crosspieces to that size.
4. Turn pairs of posts so grooves face each other, place crosspieces in grooves, check squareness, and secure with two angled 31/2-inch deck screws.
5. Cut both lattice panels to fit between crosspieces, approximately 63 inches long.
6. Each lattice panel will be sandwiched between 1-by-1s mounted to the posts and crosspieces. Create the outer layer by cutting 1-by-1s to fit between posts and nail them to crosspieces flush to their outside edges. Cut and nail 1-by-1s to fit vertically between crosspieces. Place outer side face down on work surface. Insert lattice panel, then hold in place with 1-by-1s at top and bottom.
7. To complete sandwich, mark a point 17 inches from the bottom of each post. Measure, cut, and nail lengths of 1-by-1 that extend from the top crosspiece down to this point on either side of the lattice. (After seat is in place, cut and nail 1-by-1 to fit between seat and bottom crosspiece.)
The bench seat
The seat pieces are attached to a 5-foot-long ladder-like frame, which is held in place by deck screws that run through the frame and into the four posts. To make a snug fit, measure the distance between the posts and build the bench frame to that depth.
1. Equally space three 2-by-4 crosspieces between two 5-foot-long 2-by-4s and secure with joist hangers and nails.
2. Add undermount deck fastening brackets to top of each crosspiece.
3. Cut one 10-foot-long 2-by-4 and two 10-foot 2-by-6s into 5-foot lengths. Place on a work surface, alternating three 2-by-6s (save the fourth 2-by-6 for the back) with the two 2-by-4s. Position frame on top so the outer 2-by-6s are flush with the edge of the frame, equally space middle boards, and attach with 11/4-inch deck screws.
4. Stand the side panels on their back edges and slip in the bench so its top butts against the 1-by-1s on the inside faces of the posts. Check for squareness and drive two 31/2-inch deck screws through bench frame into each post.