Post frame pier size

[bagged89s10]

I’ve been trying to find more info online but have not found any good info.

I’m building a 24x34 or 24x36 post frame garage in Connecticut. 24ft will be the truss span. I plan on putting posts a maximum of 8ft apart. The garage doors will be on the eave side. The footings will have to go a minimum 42” deep to the frost line. Speaking with the last concrete contractor, he recommends digging 52” so the 10” thick is below the frost line. I want 24” diameter footings.

I plan to use sturdi wall wet set swp66 brackets for 6x6 posts. I was originally worried about not having enough time to set them when the concrete is poured so I might layout a jig so after that concrete piers are poured I can just quickly install the brackets with little measuring.

The question is, what diameter piers should I be pouring?

 

[K'ledgeBldr]

I think 24” is overkill...
But if you want 24” dia piers, put in 24” dia piers.

It most likely comes down to not so much frostline as it does soul type. You can find your areas soil type on line through the state’s geo dept.

 

[dwouscg]

My 2 cents is 24" is overkill as well..that being said have you had a look at the specs and use guide for the brackets? I was looking into using these myself at one point. If you go to permacolumn.com you can pull it up easy. Worth noting pending any foundation design they recomend atleast 8" to provide the required rebar coverage of the bracket.

I think an issue just as important as pier size with the use of these brackets is framing design. When I bought my kit I had the option to set the pole or buy and use the brackets. The design of the framework did not change based on that choice and that scared me. Perhaps it was designed with some overkill so it didn't matter but I did not have a warm and fuzzy. Pulled straight from the design and use guide for the bracket.....

"The building must be designed to resist lateral loads through diaphragm action or other bracing means. SW and SWP brackets are not an alternative to this requirement and are not recommended for columns that do not have a lateral restraint at the top."

That being said the same company will sell you a perma column using a similiar if not the same bracket and that is 6X6 concrete buried in the ground..if there is a difference between that and a 8" DIA pier someone would have to convince me. I would even say the 8" pier is stronger since you wouldnt need to backfill around the post. Depeniding on soil conditions of course.

Again just my 2 cents from when I was looking into them.

 

[bagged89s10]

I called the mfg and they just said I need at least 2” on each side of the brackets.

To throw another wrench in my project, I had a concrete contractor come look at what I need and he thinks it might cost the same to do a full foundation. Just the extra cost of brackets, sonotubes, and extra layout time for pier spacing. He had a good point that it might be much easier for my excavator to just dig a full foundation tench.

I’m calculating costs and the cost of concrete plus the brackets and sonotubes to pour piers is roughly the same or more than concrete for a full foundation.

I’m waiting on excavation and labor costs for both.

 

[Moss]

If you can pour a wall and have it up above grade a bit for around the same cost I'd do that. The excavator can dig a trench pretty quick. When I did my red iron shop the concrete for the monolithic slab was as much as a wall so I did 5' wall and gained an extra foot of height out of the dirt.

 

[Dustball]

If you want the 24" diameter footing, you can buy bell forms that attach to the bottom of the sonotubes. This will give you the footing diameter you desire but save a lot of concrete where you don't really need the full 24" diameter.

 

[K'ledgeBldr]

If you want the 24" diameter footing, you can buy bell forms that attach to the bottom of the sonotubes. This will give you the footing diameter you desire but save a lot of concrete where you don't really need the full 24" diameter.

The “problem” with spread based footing forms is you have to dig/auger a hole that’s the diameter of the footing form...
So why would you dig/auger a hole that’s twice as wide as needed and just fill it with a tube AND dirt?

Just auger the hole, fill with concrete and rebar and call it a day! No forms, no tubes, no BS.

 

[Bretny]

The “problem” with spread based footing forms is you have to dig/auger a hole that’s the diameter of the footing form...
So why would you dig/auger a hole that’s twice as wide as needed and just fill it with a tube AND dirt?

Just auger the hole, fill with concrete and rebar and call it a day! No forms, no tubes, no BS.

That may work in frost free GA but not in NY. You want a smooth sided concrete form so the frost cant grab the sides. A rough sided form may be just as bad as not going deep enough.

 

[bagged89s10]

That may work in frost free GA but not in NY. You want a smooth sided concrete form so the frost cant grab the sides. A rough sided form may be just as bad as not going deep enough.

That’s true. I don’t want to spend $20k on a building snd have it start heaving and twisting in a few years. I rather overbuild it. I plan to live in this house and use the garage for a long time.

 

[rburke65]

Like for what purpose is what used?

 

[Dustball]

Like for what purpose it is used?

The belled part goes below the frost line to act as both an anchor to prevent frost heave and also to distribute the weight for load bearing.