How To Stabilize A Pergola

Step 1

Determine the placement of the pergola. Stretch a string line to mark the exterior outline on the ground.

Step 2

Dig holes with posthole diggers to one-third the depth of the vertical support posts. For example, for a 9-foot-tall pergola, use 12-foot posts with 3 feet underground for ample support. Dig a hole for each corner post to the correct depth and 12 inches in diameter.

Step 3

Pour 3 inches of gravel into the bottom of each posthole. Tamp it down with a shovel or hoe handle.

Step 4

Step 5

Place a 4-inch-by-4-inch post in the center of a post hole. Level the pole horizontally and vertically, checking it with your level. Lean a 2-inch-by-4-inch board up against the post at a 45-degree angle with the other end on the ground. Nail the board to the post to support the post in its level position.

Step 6

Combine ready-mix concrete and water according to the package directions. Place the dry powder in a wheelbarrow, add water and mix with a shovel until the concrete is consistent.

Step 7

Shovel the concrete into the posthole around the post until it is at ground level.

Step 8

Step 9

Repeat this process for each vertical pergola post.

Step 10

Let the posts set for 24 hours. Remove the two-by-four braces and continue the building process.