This project requires the assistance of at least one other person to complete. Sketch out the design for the arbor, including measurements.
Cut the redwood posts and crossbeams for the arbor, making sure to cut the posts longer than you will need them to be in the final arbor.
Measure and mark the locations for the two 4x4 posts that will support the arbor. Since the arbor in the project serves as an entry arch at the top of outdoor steps, the posts have to be far enough apart to easily walk between. Dig holes 18 inches deep and wide enough to give 2 inches of clearance on all sides of the post.
This arbor design is fairly small and lightweight. If building a larger, heavier arbor – or if the arbor will have added weight such as large planters – dig the holes 24 inches deep for more stability.
Pour dry concrete into the holes a couple of inches deep and level off the surface. Set one post on top of the concrete and have a helper set a second post in the other hole. Level and plumb the posts, and use a string line to make sure the two posts are in line with each other.
With both posts plumb, level and lined up with each other, pour more dry concrete around the sides of the posts to fill the holes. Check again for plumb and level, then water down the concrete. Use an old shovel or a piece of rebar to compact the concrete and get rid of any air bubbles. Allow the concrete to dry overnight or according to the manufacturer's instructions.
Center one of the two crossbeams on the posts, check it for level, then tack in place with screws. Repeat for the other crossbeam (Image 1), making sure the beams are lined up (Image 2). With both beams held in place, drill two holes through the beam-post-beam "sandwich" at one end of the arbor. For each of these holes, slip a washer onto an 8-inch galvanized bolt, then fit the bolt through the hole. Add another washer and a nut, and tighten with a wrench.
Repeat the process to secure the other end of the beams.
In this project, the posts extend above the crossbeams until the crossbeams are bolted in place. When crossbeams are in place, use a reciprocating saw to cut off the top of the posts at the top of the crossbeams on either side.
Arbors are the perfect place to display vines, decorative lighting or ornamental woodwork. For this project, the crew used eight short pieces of redwood with tapered ends, which were spaced equally along the top of the crossbeams to break up the straight lines and soften the overall look. They are also long enough to support a mature vine.