DIY Arbor Swing: How to Install Curved Wood Knee Braces

We’re sharing step by step as we build a DIY arbor swing in a beautiful backyard! This is Step 11: how to install curved wood knee braces to support the beam in an arbor or pergola.

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DIY Wood Knee Braces

As we explained in the post about how to cut your own DIY wood braces, when you’re building an outdoor open structure like an arbor, pergola, or deck, a “knee brace” isn’t about your aching knees – it’s lingo talking about the diagonal supports that help support the structure, in technical terms.

Once the wood braces are cut (and we like to cut that extra curve so they’re decorative in addition to being functional), they are one of the last steps on the structure to give it stability.

DIY Wood Knee Brace For Swing Arbor Beam Supports, Remodelaholic

Making your own wood brackets allows you to match the wood grains a textures from the wooden knee braces to the unique natural colors or color family of the lumber used for the rest of the timber frame of the project. We’re using cedar wood, but we often build outdoor projects from redwood as well.

Wood knee braces look great on open structures, or used corbel-style to support porches or awnings, for both a visual support and and actual structural support. These wood knee braces on the arbor help add support to each end of the beam, and they also add some really nice architectural style to this DIY arbor swing. We used similar knee braces on the wedding arch garden arbor, too, and we love the look!

How to Install Wood Knee Braces for an Arbor Beam Support

Depending on the application, knee braces can be installed on the face or side of a post. For example:

  • For the garden wedding arbor, the braces attach using wood screws on the side of the post and the face of the upper lattice section, to hold the 2 sections together for easy on-site assembly.
  • On the large rough timber pergola I built, the knee braces attach to the side of the post and the bottom of the beam using lag bolts.

The purpose is to provide an angled support (because triangles are strong in construction applications) to help support and reduce the tension on the right-angle connections between the posts and beams.

Attach Wood Knee Brace Corbel Support With Lag Screw, Remodelaholic

For the arbor here, we have a solid post but then TWO beam supports running perpendicular. The knee brace is centered between those two beam supports (and centered on the post) so we need to also add a support between the beam supports to attach the knee brace.

Here’s how I did it:

  1. Measure the distance between the 2 parallel beam supports and cut a piece of 2×6 to that length.
  2. Center and attach the top side of the knee brace to that shorter support. Drive the screws through the support and into the wood brace to hide them from view.
  3. Place the knee brace (with attached support) in place and clamp to hold it level and centered on the post. The lower edge of the support should be flush or just above the lower edge of the beam supports.
  4. Secure the short support to the beam supports using screws. These will be visible, so remember to measure and line up the heads to look nice.
  5. Predrill, then attach the knee brace in place on the post using a lag bolt.
  6. Repeat for the other 3 wood knee braces.

Custom carpenters might use a mortise and tenon joint (basically a slot that a peg on the brace would slide into) on an application like this for extra support and a really beautiful joint. But, for DIYers and contractors like me on projects like this, wood screws and/or lag screws are adequate.

Stay tuned and subscribe to see how we set the footings for the swing arbor, stain the posts, and more – right up until the finished project reveal!

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How To Install Wood Knee Braces On A Diy Arbor Swing, Remodelaholic
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I am the husband of the amazing Cassity of Remodelaholic. I love to problem solve and to design and build things inside and outside the house to make life better. I am a professional Landscape Architect by trade and love the outdoors.

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Lorene has been behind the scenes here at Remodelaholic for more than a decade! She believes that planning projects and actually completing them are two different hobbies, but that doesn't stop her from planning at least a dozen projects at any given time. She spends her free time creating memories with her husband and 5 kids, traveling as far as she can afford, and partaking of books in any form available.

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