DIY Arbor Swing: How to Place and Level Posts

We’re sharing step by step as we build a DIY arbor swing in a beautiful backyard! This is Step 2: how to place and level posts for a swing to prepare for the dry-poured concrete footings. This method can also be used for fence posts or pergola posts.

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How to Place and Level Posts for an Arbor or Pergola

When you’re building an outdoor structure like an arbor or pergola, it’s important that the wood posts are anchored securely and placed as accurately as possible to ensure a stable structure and to keep the measurements accurate for the crosspieces at the top. You can choose in-ground concrete footings with post brackets or set-in posts in the concrete footings. Deck blocks are not an option for a structure with a swing, and for added stability, I prefer to use in-ground posts for structures that need to accommodate movement like a swing. (Read more about pergola footing options here.)

In-Ground Footings with Brackets vs. Posts Set in Concrete Footings

In-Ground Concrete Footings w/Brackets

For this rough timber pergola I built earlier this year, I placed in-ground concrete footings beneath the existing patio and attached the posts to footer brackets. This required drilling through the concrete pad, digging out the post holes, then pouring the concrete below grade and setting the brackets in the wet concrete. Brackets like I used there are a great option when you need to build a taller structure and don’t want to use up valuable post length by burying it in the ground, or where you are installing on an existing concrete pad or plan to pour concrete anyway. Above-grade posts are also less prone to rot. But, the brackets provide less stability for a swing (even after the cross-braces are installed).

Buried Post Footings

For this arbor swing, the posts don’t need to reach as high and I wanted the added stability of the entire post width being set in the concrete, so I chose to bury the post base directly in the ground, on top of a concrete block and set in a dry-poured concrete footer (more about that in the next post). Having the wood post set below-grade does make it susceptible to rot over the years, so that’s why our first step was to seal the posts with liquid rubber coating.

The viral fire pit pergola for swings also uses below-grade posts set in concrete and Lauren reports that it’s holding up practically perfectly after 8+ years!

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How Deep to Bury Arbor Swing Posts

This DIY arbor swing is in the same climate zone as the pergola I built earlier, so the posts will need placed about the same depth to be below the frost line and prevent heaving with winter weather and freezing temperatures. The diameter of the hole and the hole depth depend on your area and the post size. For my area, this means the holes are at around 30″ deep. I sealed that bottom section of the post with rubber coating wood preservative to protect it from moisture and premature rot, which is a good idea for wood fence posts that you want to last longer, too.

To accommodate the 8″ width of the posts and enough concrete around it to keep it stable, the holes are roughly 18″ wide. Read more in this post about determining the footing size and depth for a project.

For digging holes that size, you can rent an auger and/or you can use a good ol’ fashioned hand-powered post hole digger or even a shovel. I highly recommend a wheelbarrow to haul away the extra dirt to where you need it in the yard, but a bucket works, too.

BEFORE YOU DIG: Call 811 to have the utilities marked. Do not dig until you know where the lines are!

How to Place an 8×8 Post in a Hole

1. Dig the post hole(s) to the appropriate width and depth, in the location needed.
2. Add gravel for drainage and place a thick concrete paver block in the bottom of the hole. Level the block as much as possible.
3. Next, place a 4×4 across the hole, off-center to one side. This step is optional but the 4×4 helps protect the dirt at the edge of the hole from getting shoved in the hole as you slide the post in.
4. With a partner, move the post to the hole and set the base of the post (the coated end that will be buried) on the 4×4.
5. Slowly “roll” the post into the hole using the 4×4.
6. Raise the opposite post end (the top of the post) as you slide the post, and allow the coated post end to go into the hole and pull the other end upright (more or less) as the buried post end goes down in the hole. (Watch the video above if this doesn’t make sense!)
7. Adjust the post to the center of the hole. Then, level and plumb the post in the hole. Level = horizontally straight // Plumb = vertically straight
8. Use 2x4s or other long scrap lumber as supports to hold the post in place. I generally place 2 scrap lumber pieces across the hole, overlapping perpendicular, and then another piece of wood at a roughly 45-degree angle to the ground and overlapping the post. The supports can be nailed or screwed to the post as needed, and the holes will be filled later when the supports are removed.
9. Be sure that your supports still leave access to the hole that’s wide enough to pour in concrete dry mix! I’ll show you how to dry-pour concrete footings for the in-ground post in the next installment.

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