I want to build a pergola similar to the one below and was wondering what to use to connect the posts to the ground (notice how they are at an angle to the vertical)

Angled-post pergola

Also, what is the connector/connection type used for the top angle, so that there are no visible fasteners?


That pergola was built a few years ago by Jason Roberson of Charlottesville, VA. I'd write to him and ask how it is holding up and what he might do differently.


One of the photos shows that the top joint was pinned laterally. See: http://i.imgur.com/owdVKrR.jpg

Note that the exifdata in most of the images date the photos as 2013, and don't show the lateral pin. But the photo I cropped and show above is from 2015 per exif data.

The slots in the bottom of the posts look like mortises for 1/2" steel plates sunk into a cement footing.

You can see high res versions of his photos by starting the slide show, then right-click -> View Image (firefox), then edit the image url to delete the questionmark and subsequent characters. For example:


At the ground, you're mostly concerned with keeping the posts located. You don't want bumps to slide them around. A simple steel pin or bolt in the concrete is adequate. If you like, use a short stack of washers to keep the wood (mostly) out of contact with the concrete to improve longevity.

At the top, I'd use 1/2" lag screws, countersunk and piloted. Two at each joint and penetrating 4-5" into the posts should do. You'll want to cap or plug the bores to prevent water accumulation and rot.

All hardware should be stainless or galvanized, in case it's not obvious.


The top could be a traditional mortise and tenon joint (possibly haunched for resistance to twist). You'd want the tenon to be pushed to the interior in any case, as the end grain on the joist is weak.

But @isherwood is right that mechanical fasteners are a strong alternative.

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    It sure would look impressive, but for a DIYer it's a lot of risk with some very expensive lumber. – isherwood Sep 18 '16 at 0:32
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    Can't disagree. To the OP, suggest you launch a new question (maybe even over on the woodworking.se) regarding 'how do I make a haunched mortise/tenon joint in large timbers' if you're interested in going that route. – Aloysius Defenestrate Sep 18 '16 at 0:45

This is Jason Roberson of Builderbeast. I built this pergola out of Western Red Cedar a few years back. At the top I mortised the post into the beam and pinned it from the side with a ledger lock, then plugged the hole. Everything is cut at 11 degrees. I made a jig for all cuts for consistency and calculated all the measurements as if they were rafters on a roof. The building also was not completely straight, nothing is, so i left all the beams long and field cut them. The connection hardware to the building is made by Simpson for hidden beam/joist fastening.

At the foot of the columns I had a custom Stainless steel 1/2" standoff made at the same 11 degrees. It is slotted into the bottom of the column and has a 1.5" raised platform. I wish i had taken a picture. I designed it in Sketchup and gave it to a local fabricator. I also made a hole jig for this so that i could set pins in three holes to secure it. The standoff is bolted down to a concrete footer.

Hope this helps. I'd be happy to answer any other questions Jason

builderbeast@gmail.com builderbeast.com

  • Good answer, but -1 since self-promotion is frowned upon, unless relevant to the answer: meta.stackexchange.com/questions/57497/…. Including email or contact information is also frowned upon, and invites spam. If you want to provide an email address, do so in your user profile. – mmathis Nov 2 '16 at 19:55

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