Pole Barn Post Method?

[karoc]

Pole Barn Pole Method Installation Method?

Guys nailing down some details for my 33'x80'x12' pole barn and one of them is method for the poles itself. I have read countless post,watch million Youtubes and watch and read articles at some of the metal bldgs websites. They are all different and all give good reasons as to why their way is the right way.
My question is,do I pack dirt around pole,do I pack gravel around poles or do I just pour concrete around poles?
Right now going to be 4' in ground with concrete pad bout 4" thick at bottom of the hole for the pole to set on and help with drainage little. Poles are going to be marine grade type that other members here had suggested. So this post is more about the method,all the research that I have done is leaving me with mix thoughts. So out in real world what is best way? Coming from where its mostly hot yr round East Tx.

 

[fourbyford]

I built a building using concrete... posts set at 4+ feet... no problems. This is in Wyoming... hot, dry summers and cold winters.

Our new place in Idaho came with a post frame building. PT 6 x 6's set with crushed gravel (w/fines... can't remember what they call it... lol) Weather there is not as hot or cold but, very wet. I was concerned when I saw how that building was constructed but it has been fine...

I'm planning on building onto that building and asked my neighbor (he's in the concrete business and has seen a number of these go up) and have asked the same question here...

From everybody I've talked to, and my personal observations, I dont think it makes a lot of difference... just do whatever works for you.

When I add the bay on the end of my Idaho garage, I think I've decided to use concrete because that end of the building can stay pretty damp for several months of the year. I will use sonotube and bring the concrete well above ground level... I've also done some drain work along that end of the building.

I used concrete when I built the Wyoming barn for a couple reasons... it's a pretty tall building and we get lots of wind... and that soil tends to be a bit sandy. I figured concrete would be the best plan.

Good luck with your building!


...D

 

[matt_i]

Personally I would use dirt. That's what's bearing the load eventually. But, be prepared to compact it, flooding it would also speed that process up. Pea gravel is probably used because it insta-packs the moment that its poured, but its also like having a bajiillion ball bearings which isn't as good as the native soil for solid bearing if you ask me.

It would be very worthwhile to investigate termites in your area and "soil poisons" that you can inject before backfilling. I recall Dursban but think this is outlawed for chemical reasons but there is probably a more human-friendly alternative in the modern era.

 

[Jbullfrog]

Rock is best for holding and drainage. Use 3/4- white gravel and tamp it while filling the holes.

 

[OneOfEm]

I had to use concrete due to the windload (hurricane zone). Every area will be a bit different.

 

[472scout]

I have the same question. It's impossible to make heads or tails of all the opinions out there imho. There's supposed to be a post rot study that compared dirt vs concrete, but hell if I can find it.

Make sure your cookie size/soil conditions can support the weight of your building. https://www.hansenpolebuildings.com/2012/08/hurl-yourconcrete-cookies/

 

[lakeroadster]

Re: Pole Barn Pole Method Installation Method?

My question is,do I pack dirt around pole,do I pack gravel around poles or do I just pour concrete around poles?
So out in real world what is best way? Coming from where its mostly hot yr round East Tx.

The native soil you take out when you dig the hole... put that back in when you back fill around the post.

It really is that simple.

What you don't want is to make a well for water to sit in every time it rains. Dissimilar fill materials will do just that.

Equally if not more important, is to build the building higher than the surrounding grade so water always runs away from the building.

 

[iagsxr]

I know that two of the counties that adjoin the one I live in have drastically different code requirements from each other for setting poles. The one you absolutely can't fill the hole with cement. I'd start with your code and do whatever most of your local builders do.

 

[theoldwizard1]

I'm a fan of Perma-columns or even better a concrete footing (Sonotube) that is at least 6" above finish grade.

If local code does not require concrete, 3/4" sharp gravel is good. Some codes require a cured concrete "cookie" in the bottom before setting the post and back filling.

 

[lakeroadster]

I a fan of Perma-columns or even better a concrete footing (Sonotube) that is at least 6" above finish grade.

If local code does not require concrete, 3/4" sharp gravel is good. Some codes require a cured concrete "cookie" in the bottom before setting the post and back filling.

Back filling the post hole with gravel is absolutely the worst thing you can do.

You've just created voids that will fill with water every time it rains.

 

[CraigStu]

6 yrs ago I had a garage addition done and needed to pull some fence down to make room. I was going to redo the fence and asked him what he thought since we had pulled them out of plain dirt. He said people are getting away from concrete because no matter what one does to seal it to the post it actually ends up holding rain water against the post. So it will rot more easily. So that is one side. But I think your local code is what you need to consult because you can't argue w/ them.

 

[MrSurly]

I looked at every method, considered (actually planned for) back-filling with poured concrete. Ended up NOT doing that. Instead, I dumped two bags of Sakrete in the (48"x18") hole, set the post then backfilled with heavily tamped native earth.
As an engineer offered on this: The concrete at the bottom is there to create a solid 'pad' to distribute the vertical load that is on the post, over the 18" diameter surface area of the bottom of the hole. The concrete gives the post a big footprint for the load, 254 square inches versus 30 square inches (post only). There only needs to be enough concrete in the pad to be strong enough to do that job. If you add concrete back-fill, since the diameter of the hole hasn't changed, you have NOT increased the surface area (of the earth) that's bearing the load.... you've only ADDED significant WEIGHT to the post for no reason. conservatively estimated at 800lbs per post of additional weight. this would have my building weighing some 14,000 lbs more...for no gain.
After looking it it that way, the presumed benefits of the concrete back-fill didn't make sense to me.
In different soils, different locations, concrete back-fill may offer better wind loading or uplift protection, might be required in hurricane zones, etc. Just didn't make sense in my case.

 

[Bobthetractor]

I'd do concrete. I know folks say science says packed dirt is good enough for high wind uplift but I have trouble believing it compared to concrete. You do have less flex with concrete and you can shear a post easier with high wind events but that would usually mean you didn't have adequate bracing. Also, consider 8x8's everyone around me uses 6x6's and I haven't seen any fail but I ended up getting mine for a nominal extra cost. I did look at 10x10's for the fun of it but the only supplier I found that had them in 20' length was something like $1,000/post and they were coming from Washington or Canada. Humble, TX is closer to the coast than I am...look into bracing, your truss engineer should give guidance and within reason you can't brace too much and 2x6's are cheap and an easy DIY even after the roof is up.

Biggest point to make is to keep in mind that there isn't just one type of "treated" post. You can still get 2.5 CCA in some places for saltwater marine construction, I think this is too high but just making a point. .4 is too low IMHO. I won't get into a CA vs CCA debate. I don't recall if IBC prohibits treated wood in a living area I know they frown upon it (to the extent you're building to code or making a living area) but you can encapsulate later if that's a concern.

 

[GMCGarage]

Re: Pole Barn Pole Method Installation Method?

Guys nailing down some details for my 33'x80'x12' pole barn and one of them is method for the poles itself. I have read countless post,watch million Youtubes and watch and read articles at some of the metal bldgs websites. They are all different and all give good reasons as to why their way is the right way.
My question is,do I pack dirt around pole,do I pack gravel around poles or do I just pour concrete around poles?
Right now going to be 4' in ground with concrete pad bout 4" thick at bottom of the hole for the pole to set on and help with drainage little. Poles are going to be marine grade type that other members here had suggested. So this post is more about the method,all the research that I have done is leaving me with mix thoughts. So out in real world what is best way? Coming from where its mostly hot yr round East Tx.

Based on your location, you should have it engineered, you seem to be in a hurricane zone, so wind could control the footing. Unless if it gets wiped out, you are ok with that and will rebuild.

 

[nadogail]

I see 14 responses to your question and each of them are written with great confidence.

IMHO, your local building authority will tell you what their requirements are, follow their guidance because if they are in error you can point your finger at them, rather than the guy in the mirror.

As for myself, not being familiar with your situation I would investigate used pipe welded together and set in concrete.

 

[karoc]

Thanks guys for all the input, where I will be moving for this project there are no building codes,no inspections and no HOA'a so this is the reason for my questions. But I see there are few locals here that is familiar with ground conditions. Game plan is in works, getting excited about this,thanks to GJ members for the help.

 

[cj7jeep81]

Thanks guys for all the input, where I will be moving for this project there are no building codes,no inspections and no HOA'a so this is the reason for my questions. But I see there are few locals here that is familiar with ground conditions. Game plan is in works, getting excited about this,thanks to GJ members for the help.

I also highly recommend perma columns. They add a bit to the cost, but on my pole barn I have 0 wood in the ground, and since I plan on using this building for the next 30 years, that small increase was worth it.

 

[matt_i]

I looked at every method, considered (actually planned for) back-filling with poured concrete. Ended up NOT doing that. Instead, I dumped two bags of Sakrete in the (48"x18") hole, set the post then backfilled with heavily tamped native earth.
As an engineer offered on this: The concrete at the bottom is there to create a solid 'pad' to distribute the vertical load that is on the post, over the 18" diameter surface area of the bottom of the hole. The concrete gives the post a big footprint for the load, 254 square inches versus 30 square inches (post only). There only needs to be enough concrete in the pad to be strong enough to do that job. If you add concrete back-fill, since the diameter of the hole hasn't changed, you have NOT increased the surface area (of the earth) that's bearing the load.... you've only ADDED significant WEIGHT to the post for no reason. conservatively estimated at 800lbs per post of additional weight. this would have my building weighing some 14,000 lbs more...for no gain.
After looking it it that way, the presumed benefits of the concrete back-fill didn't make sense to me.
In different soils, different locations, concrete back-fill may offer better wind loading or uplift protection, might be required in hurricane zones, etc. Just didn't make sense in my case.

If you consider the post bearing on the earth in a tipover/moment scenario where loading on the side of it is trying to lever it out of the earth, a concrete fill would add a lot more bearing area against the native soil. Consider the side of a 12" x 12" wide x 48" deep concrete vs a 5-1/2" x 5-1/2" x 48" bare wood. However there's typically enough moment bearing on the buried part of the wood post so that no extra is needed.*

The other detriment of concrete is that concrete will always pull back very slightly from the wood as it cures & shrinks and then there's a thin slot that water is guaranteed to find and fill.

The native soil however can only pack tighter over time. The settling can be problematic for other reasons but the soil bearing can self-improve.

* another analogy is a jib crane foundation, it has to bear against the soils to gain the appropriate tipover moment and so a relatvely massive concrete cube has to be poured...I put one in a 48" x 48" x 48" for a 500 lb x 12 ft arm crane. The extra vertical weight very mildly helps the tipover as compared to the 2000 psf bearing of the soil.

 

[ladderwell]

I had to follow code. Concrete required in my county.

 

[theoldwizard1]

Back filling the post hole with gravel is absolutely the worst thing you can do.

You've just created voids that will fill with water every time it rains.

Just the opposite ! The gravel allow the water to move away from the wood. It stays away even if the ground is still very damp.

If the hole is filling every time it rains, the grading is wrong !

 

[theoldwizard1]

I'd do concrete. I know folks say science says packed dirt is good enough for high wind uplift but I have trouble believing it compared to concrete.

If uplift from high winds is a concern, then there is even more reason to pour a footer (Sonotube) WITH a foot.