DIY Network

How to Install Arbor Beams

Finish the arbor by adding header boards and joists.

More in Outdoors

finished arbor adds interest to backyard setting
  • Time

    Several Weekends

  • Price Range

    $500 - $1,000

  • Difficulty

    Moderate to Hard


Step 1: Install Header Boards

With the uprights secure, work can begin attaching the header boards to the posts. These 2x12 boards are attached to either side of the posts to help support the arbor. Measure and mark the correct length of each beam, and cut them to length using a circular saw. Secure the beams to the posts using 3 1/2" decking screws. Note: Although the patio has a slight slope away from the house for drainage, the arbor roof should be installed so that it's level. Therefore, check to be sure that the header boards are level as you install them. This will give the proper appearance to the arbor and a level reference for installation of cabinets and cabinet tops.

secure the beams to the posts

Courtesy of Lucie Rowe

Step 2: Snap Chalk Line

Once the first two header boards are installed, snap a chalk line across the next set of posts. Our design calls for the bottom of each beam to be 14' above the ground.

snap a chalk line from post to post

Courtesy of Lucie Rowe

Step 3: Line up Beams

Line up the next beam along the chalk line, check for level and attach the beam with decking screws. Repeat the process on the other side of the posts.

line up next beam level with chalk line

Courtesy of Lucie Rowe

Step 4: Tighten Down Beams

Once all of the header beams have been secured in place, it's time to permanently secure the structure with lag bolts. Using a 12" wood bit, drill a hole all the way through the drop beams and post. Once the hole is drilled, hammer in a 12" carriage bolt.

hammer in carriage bolt through beam and post

Courtesy of Lucie Rowe

Step 5: Add the Bolts

Slip two washers and a nut onto the carriage bolt and tighten down securely. Place two carriage bolts at every post location.

place two carriage bolts at every post location

Courtesy of Lucie Rowe

Step 6: Paint the Beams

Once all of the beams have been installed, prime and paint the ends of each board using a small paintbrush.

Step 7: Use Jig to Shape Joists

The arbor joists will cap the arbor and run perpendicular to the header beams. Our design calls for the joists to be cut with a diagonal as a visual corner detail. In order to make perfectly uniform cuts on all of the joists, we created a custom jig. Since there are 22 joists in the arbor, the jig will be used to mark 44 separate cuts. The jig will help simplify the process of making all those cuts so that they are identical. To make our jig, we simply cut a 45-degree angle on both sides of a piece of 3/4 plywood. Attach a 3" strip to the leading edge.

custom jig created to make uniform cuts in joists

Courtesy of Lucie Rowe

Step 8: Slide Jig on Joists

Slide the jig into place on the end of each joist to mark the proper angle. Use a circular saw, and cut along the marked line. Repeat the process to make the cuts on both ends of all of the joists. Repeat the steps until all of the posts are installed.

slide jig into place on end of each joist

Courtesy of Lucie Rowe

Step 9: Add Trim to Posts

As a final touch, use painted 1x6 trim to conceal the metal brackets that support the arbor posts. The wood pieces used to create the trim are miter-cut, and specially hollowed out using a router to fit over the pieces of the bracket that extend out at the base. Once the pieces are cut and painted, install them using a brad nailer. Use wood shims so that the trim is installed about 1/4-inch above the floor surface for water drainage.

shims used under trim to help with water drainage

Courtesy of Lucie Rowe