1. Main Attraction Installing an arbor on the edge of a deck will draw visitors to its shade and shelter, and keep them from congregating in front of the doorways. Alternatively, placing an arbor at the entryway emphasizes the stairway and conveys a sense of welcome.
2. Shade Spacing An arbor’s topmost lath pieces, milled from ripped 2x4s and installed on 6-inch centers, cast partial shade on a deck. The lath also contributes to the arbor’s strength and helps restrain the joists. To prevent bowing and twisting at their ends, lath pieces should extend no more than 4 to 5 inches beyond the edges of the outermost joists.
3. Beams and Overhangs A general rule for the length of an overhang on an arbor is to double the nominal width of the lumber. For instance, a 2x8 joist should extend 16 inches beyond the beam it rests on. Bolting two cross beams together and attaching them to one side of a column can look too massive and heavy, so it’s usually best to flank the column with one beam on each side, for a lighter, more delicate look.