# What size sonotube??



## kevin1005

Hey Guys,

I just have a quick question, from what I've read online, people say that the sonotube needs to be double the size of the post, or pole you are using, or at least thats the general rule of thumb. 

I'm looking to build a pavilion this summer, and would like to use 8x8 cedar posts, even though the plans i've found only require 6x6. I just like the look of the 8x8 more. What size base would you guys use in this instance? I've asked the building department and they aren't very helpful. I asked if I needed drawings, and they said no, but also gave me no direction on what they'd want to see, so I'm posing the question to you all. Thanks in advance.


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## joed

Just for reference an 8x8 post is 11.3 inches corner to corner.If you want a minimum of 2 inches all the way around that means you need to add 4 inches. I would use a tube less than 15 inches.


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## Nealtw

Almost everything we build gets an 8" tube I have used a 10 inch when an engineer called for it because it was holding the corner of the house up.
What ever you use at the top I would fit it inside making it no more that 8" square on top because the top want to be at patio height if the deck is concrete and there is no need to see the round sticking out.

The bigger question is frost depth and footprint for the weight you will be adding. Do you need a footing, there are some plastic things that fit the bottom of the tube.


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## Guap0_

For 8x8 posts, I would use a 12" tube.


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## Nealtw

Guap0_ said:


> For 8x8 posts, I would use a 12" tube.


 It is about the weight, not the size of the wood post. a few years ago the post could have been 4x4 the weight has not changed.


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## Guap0_

What about the size of the bracket that gets set into the footing?


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## SPS-1

Nealtw said:


> It is about the weight, not the size of the wood post. a few years ago the post could have been 4x4 the weight has not changed.


True, but I have to agree with Joed that it will not look right if the post is overhanging the sonotube. Top of concrete should be a few inches above grade, so would be visible. 8x8 post not going to look right on an 8", or probably even a 12" sonotube.


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## joed

My info was based on setting the post in the concrete and the concrete being too thin at the corners of the post and splitting.
If you are mounting a bracket on top of the concrete that would be different.


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## Nealtw

Depending on the look you are going for I guess.
This is an 8" tube on a 30" footing. top of tube was same level as the deck the and not visible under the post and the post is 1 inch above the tube and deck on a hidden post leg I will find a link to that.


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## Nealtw




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## Nealtw

When the post is bigger you cut the slot in the bottom with a chain saw and nothing to see but the bolts which can be countersunk and plugged.


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## Guap0_

I never used or even saw one of those post connectors.


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## Nealtw

Guap0_ said:


> I never used or even saw one of those post connectors.


 Timber framing uses stuff like that all the time.


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## Nealtw

If you do this and pour a deck level with the concrete post you get to look at that joint for the rest of your life.


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## ron45

In my neck of the woods it's 3x post width = _____

In your case that's 24".


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## stadry

we use flitch beams a lot but uncertain why its applicable in this thread


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## Nealtw

ron45 said:


> In my neck of the woods it's 3x post width = _____
> 
> In your case that's 24".


 Are doing that with a footing? Or is that the foot print to the ground?


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