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How to Anchor a Garden Arch

By Wade Shaddy
Some arch anchors are removable.

Garden arches, arbors or pergolas all have similar designs: vertical posts that are anchored to the ground. In most cases, no other support is provided other than this contact with the ground. Adequate support is needed to ensure that the arch stays put in all kinds of weather. There are several ways to go about it, including spiral ground anchors, bolt-down brackets or holes filled with cement.

Spiral Anchor

Step 1

Stand the arch in its desired location. Mark the locations of the vertical posts on the ground.

Step 2

Insert an 18-inch piece of rebar horizontally through the top of the spiral anchor, splitting the difference on both sides.

Step 3

Place the sharp, pointed end of the anchor on the ground where you marked the bottom legs of the arch. Apply downward pressure to the anchor with the rebar while twisting it clockwise to drive the anchor flush with the ground. Do the same with all the legs of the arch that apply.

Step 4

Insert the posts or ends of the legs of the arch into the bracket, box or upright supports on the top of the anchor. Drive 2 1/2-inch screws into the drilled holes in the bracket with a drill/driver to secure the arch to the anchors.

Post Base Anchor

Step 1

Stand the arch in its desired location. Mark the locations of the vertical posts on the ground. Dig a hole two times bigger than the diameter of the post, 12 inches in depth, with a shovel.

Step 2

Pour the hole full of wet concrete. Insert the elevated post base into the concrete, flushing the box or bracket with the top of the concrete. Measure the distance between the legs of the arch. Use the measurement to center the brackets to ensure they fit the legs. Insert a scrap four-by-four post into the box. Use the scrap piece to level the bracket with a bubble level. Allow the concrete to dry. Repeat with all the legs that apply to the arch.

Step 3

Drive 3-inch screws into all the drilled holes in the bracket with a drill/driver.

Concrete Set

Step 1

Stand the arch in its desired location. Mark the locations of the vertical posts on the ground.

Step 2

Dig holes with a shovel three times the diameter of the posts, 18 inches deep. Shape the bottom of the hole flat and slightly wider than the top; this prevents the post from sinking over time. Tamp down the dirt with the blunt end of the shovel at the bottom of the hole to firm it. Add gravel to the holes to a depth of 6 inches. Tamp down the gravel lightly.

Step 3

Stand the feet of the arch in the holes. Place a level flat and vertically against the posts to plumb them. Use scrap boards to support the arch, placing them diagonally as needed to brace it.

Step 4

Pour the holes full of wet concrete. Check and adjust the arch for level and plumb, moving the braces as needed. Allow the concrete to cure for two hours. Check and adjust for level if needed. Allow the concrete to dry before removing the braces.

 

Things You Will Need

  • Rebar, 18-inch length
  • Spiral anchors
  • 2 1/2-inch screws
  • Drill/driver
  • Shovel
  • Concrete
  • Elevated post bases
  • Level
  • 3-inch screws

Tip

  • If the spiral anchor is difficult to drive into the ground, soak the ground with water before installing it.

Warning

  • Wear goggles and follow all safety precautions when using power tools.

About the Author

 

Specializing in hardwood furniture, trim carpentry, cabinets, home improvement and architectural millwork, Wade Shaddy has worked in homebuilding since 1972. Shaddy has also worked as a newspaper reporter and writer, and as a contributing writer for Bicycling Magazine. Shaddy began publishing in various magazines in 1992, and published a novel, “Dark Canyon,” in 2008.