Home>Discussions>EXTERIORS>Building a covered patio, how deep should posts be?
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Blue Sky
Building a covered patio, how deep should posts be?


I'm planning on building a covered patio about 8' x 8', 6' high. I'm thinking of 4 posts encased with concrete to a depth of 4'. Is that deep enough? How much concrete should surround each post? Do I need more than 4 posts? I'm in central California (no snow, hot in summer 95-105 degrees, temps usually drop to 40's in the winter), in case you guys need that info to help me. Under the patio I'll be laying bricks or paver stones. As for coverage, I'm thinking a lattice initially, then I'll probably lay some aluminum or plastic cover on top of the lattice. Purpose of this structure is to give some of my potted plants shelter from the elements. If you guys have any links/info/photos/drawings I'd really appreciate it. My handyman ability is average (have done mostly everything around the house and on cars), just nothing this large.

Thank you!

Re: Building a covered patio, how deep should posts be?

4' is plenty deep. Usually the depth is determined by the frost line. Since your in CA, and your winters are mild (unless your in the mountains), you really don't need to go deep. 2' is probably sufficent. Amount of concrete is determined by the size of your post. Here in the North East we typically have 4x4 PT posts sitting in 8 to 10 holes up to 4' deep. Set the post, then fill with concrete. If memory servers me correctly, 2 80lb bags of quickrete will fill a 2'-3' hole with 4x4 in the center.

Blue Sky
Re: Building a covered patio, how deep should posts be?

I did some more asking around, and was told that indeed 2' deep is enough. Thanks for Quickrete info.

Rodney H
Re: Building a covered patio, how deep should posts be?

In every deck plan I have ever seen, it ALWAYS says to go at least 4 feet, for good support, and even deeper when you live in colder climates, so you are below the frost line.

Deeper is always better, no matter where you are located. I have seen too many decks that heaved, or settled, because the footings were not deep enough.

Enjoy your deck.

A. Spruce
Re: Building a covered patio, how deep should posts be?

As a fellow Californian and a semi-retired contractor, I offer this:

DO NOT set the posts in concrete, rather, wet set a steel, elevated post bases into a pool of concrete that is at least 12" square and 12" deep. If your structure increases in size, then increase the depth accordingly. The reason for this is that wood set in concrete is going to rot, PERIOD, whether you use a pressure treated post or not.

From there, use at least a 4x4 post. According to your plan of an 8' square structure a 4x4 will suffice, much larger than that and you'll need a slightly larger post.

Because you've used a pier style support base, you'll need to build structural stability into the arbor/patio cover and that is done by using knee braces (angle braces ) at the top of the structure where the post meets the horizontal "cover".

I would recommend that you Google "patio cover", "arbor", and "pergola" for ideas and designs. While the structure you are interested in is not difficult, it is important to incorporate both design and structural components to achieve a sound design and aesthetic result.

Please post back with more details so that we may further assist you with the design and implementation of you project.

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