If you’re building a pergola, you will need to find a way to install your pergola posts. There is a simple way to install footings (check out this article on installing deck footings) if you want to put the posts directly into the concrete, but many experts contend that for the long-term, installing post brackets into the concrete is the better choice. Brackets, which keep the wood post out of the concrete, tend to extend the life and support of the post wood. This tutorial will walk you through the straightforward process of installing brackets into concrete for mounting 6×6 pergola posts.
For 6×6 pergola posts, 12” concrete forms are recommended. Also, check your zone for the freeze depth to determine how deep your concrete support needs to be. In our zone, this is 30” deep. Use a hand saw to cut the 12” concrete form to size. Place the form into your dug hole.
Run strings as needed to determine the placement and/or alignment of your post, then check the bird’s-eye view of the strings. Depending on the type of your bracket, be sure that the part of the bracket that will be extended into the concrete is in the inner third of your concrete form. In this example, the 6×6 brackets have a central post.
As you can see on the second form, though, the bracket post will not be in the inner third of the concrete form, so the hole needs to be dug out and moved to the right.
Use a pry bar and/or shovel to make the hole bigger on that side. Clear out the dirt.
Place the concrete form back into the hole and check for the bracket placement. This is better; as you can see, the post is in the safe zone. Of course, perfectly centered is always best. But that doesn’t always happen.
Spray an inch or two of water into the bottom of your concrete form.
Pour some bags of fast-setting concrete into the concrete form. (You can add a little water in between each bag, if you want.) It’s important to find concrete mix that is specifically for posts; this allows you to mix directly in the hole, rather than having to pre-mix in a bucket or wheelbarrow or whatever. It’s a very slick and convenient way to do concrete in an instance like this.
Use the pry bar in an up-and-down movement to mix the powder and water. Remember that this concrete is fast-acting, true to its name, so you need to mix it thoroughly but quickly. This mixture is too watery at this point.
Add water or small amounts of powder until the top is a semi-solid mixture that will hold the bracket in place. Remember, it doesn’t need to be perfect. Don’t take too much time getting the mixture “just right,” but be aware that the concrete needs to be able to support the bracket exactly as it sets and dries.
When the concrete is ready, place a small string with a very small weight at the bottom of it on the corner joint of your strings.
Gravity will work in your favor, giving you a third line for “leveling” the bracket – two up top at the bird’s-eye view, and one hanging down from there.
Immediately push the bracket into the concrete in as close to the actual placement as possible. Adjust as needed, but time is working against you from this point on, so be quick.
When your bracket is perfectly positioned, use a small hand shovel to press concrete tightly up against the bracket post.
You can also slope the concrete away from the bracket post, or just to smooth the concrete flat if you want. Check everything for level one last time, then leave the bracket alone while the concrete dries and does its thing. Congratulations! You’re one step closer to completing your pergola…a step that is arguably the most important one, too. When the concrete is completely dry, you’ll be ready to mount your pergola posts.