Al and Robins 20x30 1 1/2 near Lake Eufaula, OK

[ajbremer]

I sure would like to get out there and start to dig my front porch pier holes but there's still snow on the ground here in mid-east Oklahoma. Oh well, it'll happen!

[CjAl]

Good to see you back at it Al

[ajbremer]

I've decided to build a garage on the lot that I own next to the lot my house is on. It'll be a 26' x 36' and I'm going to build it like a pole-barn, with dug piers holding posts up. In order to save money I'm going to skip concrete and go with a pad made out of crusher rock and pea gravel. I've heard that people go with that and that it gets really hard and flat. Are there any good links around here where people have built a garage of this type?

[ajbremer]

I found a pretty good video of someone on youtube who shows how to build a pole garage without concrete and on a slope. It's very close to the way I plan to do mine:
https://www.youtube.com/watch?v=a5zmuRUiFwo

[ajbremer]

Front end loader was over today and we removed trees, chain sawed, and leveled a pad and got it ready for crusher-run. The pole-garage will be 26x36.
https://youtu.be/CVh-GfRl-X0

[ajbremer]

I'm close to putting my posts in for my 24x32 pole garage. I talked to a friend recently who had a pole barn built and they didn't use concrete for the post - just the dirt. It was explained that the 'local soil' is better around the post because if it was to move the void would be replaced by more soil. If it was concrete, the result of movement would be that the post would 'bore' more into the ground.

It seems to me that the surface area of the soil around the concrete would have stronger gripping power (especially on the down force) than just dirt around (or on the bottom of) a wooden post. BUT...apparently there are pole-barns being put up without concrete. If I knew I could get away without using concrete or gravel around a pole barn post I would do it.

[MountainDon]

Just ram the dirt back into the hole around the post. Use a digging bar with a mushroom head for tamping. The secret in a good hard tamping job is to refill in layers; called lifts in the dirt trade. Place 6 inches of dirt in the hole and tamp hard. Repeat till full. Mound the dirt around the post so water runs away from the post rather than to the post. I've never used concrete for filling around posts of any kind.

[rick91351]

A couple observations from someone that has set hundreds of posts.  At this late age feels more like thousands...  To me personally I would never set a fence post with concrete other than maybe a well used gate post, or chain link posts.  The gate post we used for such was a thick walled scrap pipe about eight inch in diameter.  Doing so I would not use post mix.  But good old everyday sack-crete.     So what does that have to do with a pole barn?  Surprisingly much.  Concrete to wooden post to plastic anything you put into the ground starts to decompose.  Agreed some more quickly than others but never the less.  Pressure treated posts make huge disclaimers as to how long they will last.  Unless it is a local ordinance requiring they be set in concrete.  Smart wise thing is just dirt.  Well tamped and I mean well tamped like MD outlined.   Now if done properly you will not have anywhere enough dirt to put back in to the hole.  Just a fact of life. 

Now say one of your posts even if pressure treated (PT) rots off.  What you have to do in this case - on a pole building and it becomes a problem - then you dig right beside it.  Might have to jack hammer like the slab that that point but dig down beside the defective post you bury a cripple (short post) beside it. Tamping it in best you can.  Then drill through both posts and bolt it a couple times with tread all.   Now if you are having to do that with a cemented post you have a real problem.  Some say well if it is concreted in they will not rot.  Rotting actually occurs right at ground level or a small distance below but mostly right at ground level.  Take it from someone that has had to dig out more than just a few conventional 'planted' posts and a cemented it is huge hard work.

But if you decide you need to cement I think I would use post mix you might have a lot better luck breaking it out.  There is another product that I have seen used.  It is pellets you pour in to the hole - add water - let sit.  When it hardens it is like concrete - but you can get through it with a good digging bar and a lot of time and sweat.           

       

[MountainDon]

Now if done properly you will not have anywhere enough dirt to put back in to the hole.  Just a fact of life. 

Right, I can always pound all the dirt into the space around the pole and come up short if I really work it.

[ajbremer]

Why thank you fellers, I learned a lot right there! Do many people make the mistake of setting their wooden post in the ground using concrete types of stuff instead of dirt?

[MountainDon]

Only an opinion... but I'd say way too many use concrete around their wood posts. Maybe a majority of DIY'ers.

[rick91351]

Al I would never say anyone is making a mistake any more than debating who is a better guitar player.  I built several sets of working cattle corrals when I was in high school and collage.  Then just have been around a lot of cow calf operations.  My thing is just the experience of being raised  on a ranch - farm.  I truly think there is just a lot of assuming that you have to cement to make it last forever.   

[nailit69]

My old man swore by sand and water... set hundreds of posts that way... most if not all still standing to this day... 10 ft. post/RR tie buried 4ft. in the ground.  On that note... a friend of mine worked for one of the largest pole builders in western Wa. state (google that sh!t) and that was thier preferred method as well.

[Don_P]

A footing under a post spreads out the load from the post over a larger surface area. For instance a 6x6 post has roughly 1/4 square foot of surface area on its bottom. In average soil of 2,000 lb per square foot bearing capacity the post can then carry a 500 lb load without being in danger of settling. Typically a post carries more load than that so we put a spread footing under it. I typically dig a 2' square hole and pour a concrete footing... 4 square feet of bearing area, the post can now carry 8,000 lbs safely vs the 500 lbs of just a post end. The footing doesn't have to be concrete, it can be pieces of 4x or 6x treated forming a footing. Attaching the post well to the footing or to 2x boards lagged to the sides of the post while backfilling help prevent uplift in high wind. The uplift then has to extract the soil  along with the post rather than just the post.

At the ground surface a concrete collar or slab is sometimes poured. When the engineers are figuring out how much bracing the posts are contributing to the building they can figure out how much this "constrained" condition contributes to the bracing. I personally don't like posts embedded in concrete but do like to set them on concrete.

[ajbremer]

Thanks Don_P, that was great information. You mentioned that average soil has 2,000 lb per square foot bearing capacity, but what about when you pound the soil down around the post in layers and pound a few layers under the post before setting it, wouldn't that increase that capacity? This leads me to another thought, if I had a pole barn that is 32' long and is being held up by 5 posts 8' apart from each other - how much weight is each post carrying? (average pole barn wall?)

[Adam Roby]

Hmmm... I have to say I am quite surprised about all this talk of wood in the ground... I figured members would advise against it.
This site tends to be biased against post/pier buildings in general, so I figured advice on anything related would not be as forth coming. 
I stand corrected. sorry for misjudging.

I had a friend that used to swear by using pea gravel/crushed stone instead of concrete, but he did have to realign his fences periodically.  He is also a pretty lazy guy so I really doubt he compacted every 6 inches.

Would anyone also suggest using tar or some other wood protection to increase the PT wood's longevity in the soil?  I suppose that might also impact the quality of any groundwater, so might not be legal. 

[ajbremer]

I went to my local lumber yard today to get some quotes on 5"x5"x14' post ($35.00 - $36.00) and I mentioned to the guy about putting post in the ground without using concrete - he thought it was a crazy idea and mentioned that 'around here' they always use concrete for posts or the walls will buckle and move.

[John Raabe]

Concrete can hold water against the post (perhaps not a problem in dry climates). Crushed rock, well packed, will drain water from the hole. You can prolong the post life with a coating of roofing tar for 12" either side of grade (the area where rot is most likely).

later... Bracing is what provides lateral stability (not what you pack in the hole) and is important enough to have it engineered for a pier foundation.

[Don_P]

Hmmm... I have to say I am quite surprised about all this talk of wood in the ground... I figured members would advise against it.
This site tends to be biased against post/pier buildings in general, so I figured advice on anything related would not be as forth coming. 
I stand corrected. sorry for misjudging. 

My bias is against poorly braced pier and beam foundations, I've consistently tried to move folks with that notion to use post frame construction instead. Foundation grade treated would be the best way to go. If the post runs from footing to top plate and is braced by the wall, life is good.

AJ, what is causing their posts to buckle? Buckling is typically caused by overloading a column. Constraining one at ground level would shorten a column's "effective length" but if you're in that territory you probably just need to decrease post spacing, shorten the walls, increase the post size... something along those lines.
Compacting soil does increase its' bearing capacity, I read a book on soil engineering one time. I've now told you everything I remember from it. I do ram gravel into the bottom of a pier hole if it feels like it would benefit from tightening it up. You won't get where you need to be with just a 6x6 post end unless it is on a big rock.

Post load, 8' span x half of the 24' roof width= 96sf, for you I'd use 30psf total roof load, 3000 lbs, the walls wouldn't go more than 10psf so you're up to around 4000lbs per post. So if the soil is good for 2000 psf you need about 2 sf of footing. 2 pieces of 6x6 2' long side by side with a 2x12 on top to make them into a 1'x2' pad that the post sits on would do it.

Going on to make some assumptions towards the buckling question. If the posts are 14' long 6x6's in #2 SYP the allowable axial stress is 300 psi, you're at about 130 psi. Buckling in that sense... true buckling of the post isn't an issue.

There are also plastic post sleeves that increase post life.

[ajbremer]

Thank you John 'sir' and Don_P!

Hey Don_P, I may have used the wrong term (buckling) as far as the posts. I don't particularly remember exactly what the lumber yard worker said about the walls moving if their done without concrete, I just remember that he thought it wasn't a good idea and mentioned that they always use concrete in pole barn posts around here.

As far as your last post: I'm first wondering about using the treated 6"x6"x1' posts along with a 2x12 for a footing in the ground for my posts to sit on. Will the ground eventually eat up all that wood? What if I poured a little concrete footing in the bottom of the hole for the post to sit on, used a plastic sleeve around the post, and then just pack the dirt around it - that seems my best way to go.

I have another question about the 'banding' method that I should use at the top of my post but first this. I realize that this site doesn't sell plans for pole barns and is not 'countrypolebarns' or anything like that. I did purchase my house plans here and I did build my house and I have this long thread to prove it but now I've found myself with a bunch of used cars and I need a place to work on them so I realized that I needed a garage and I figured that this site and the knowledge that you guys have could easily answer all my questions. So if I start to fill this thread up with too many pole-barn/garage questions and if you think it is swaying too far away from actual country plans homes then I will refrain from further pole barn/garage questions. Actually, I did search this site for pole-barn plans but found none.

[MountainDon]

I believe concrete is used around posts many times as it is easier, especially if there are a lot of posts and the concrete comes off a transit mix truck.  Somer will consider it easier even if they are mixing concrete in a small mixer. Some will pour dry mix in the hole and add water' also easy, easier than pounding dirt. Pounding dirt works though.

[Don_P]

Concrete makes for a cheaper, easier, and better footing. A wood footing is not going to rot, the post will rot right around ground level long before wood that is well buried. Decay fungi need, moisture, temperature, food (the wood), and oxygen. well underground there is little oxygen where at ground level there are all of the ingredients the rotters need and plenty of innoculants in the topsoil layer.

There have been studies on the plastic post protectors and they seem to conclude that even with an open top free to let water in, they are protecting the post from the soil and do make them last longer... well using that logic, John's tar method should be better and there is one post manufacturer that is basically hot dipping the end in a rubber/tar type coating and wrapping string around the gooey post for abrasion resistance then baking that coating on. Continuing with that logic, is a concrete filled hole any worse? But I have seen it seem to rot posts quicker than I think they would have otherwise.

The "banding" around the tops of the posts is a beam that carries the trusses. It should be properly sized and notched into the posts, not simply nailed or bolted to the sides of the posts. I'll check it in a bit, gotta go unload the ranger, we accidentally loaded about 2 tons of sawmill lumber on it, she's not happy  .

[Redoverfarm]

Concrete makes for a cheaper, easier, and better footing. A wood footing is not going to rot, the post will rot right around ground level long before wood that is well buried.

Don I think the biggest problem with using concrete is that they do not slope the top and did not raise the portion of concrete above the ground level.  Yes it takes a little longer and you have to go back a couple times and keep pulling it up the post to get that bevel but that really is no problem as within an hour or so it will keep it's form. 

If they try to make a nice level pad around the post then they are asking for trouble.

[Don_P]

OK, got a happy truck again  A friend came over to help at the sawmill yesterday and we were merrily sawing and stacking, when I looked back there the tires were about to blow. Got about half off last night and the rest a bit ago, red oak, cherry, poplar and a locust.

That would certainly help John. One of the arguments I've heard against is that the post shrinks, water gets in the gap and just sits there keeping the post juicy. Sloping to drain at the top would certainly help. Concrete that forms a larger surface area does help "constrain" the post to some extent.

The roof carry beam at the tops of the posts, we've already figured there is 3,000 lbs of load with an 8' span, it is uniformly distributed. I'm assuming Al is using #2 SYP. A double 2x10 would do the job. I'd use an old detail from the land grant college plans... notch opposite sides of the post top 1.5" deep for the height of the 2x10s, run one on each of the opposite faces, leaving a 2.5" gap between the 2x10's. Rip some 2x6 material to 2.5" to insert vertical pieces between the beams on 2' centers.  Cut them long enough to run from the bottom of the 2x10s and sticking up enough to run alongside of the trusses, nail the trusses to those vertical pieces, poor boy hurricane tie and truss bracing. The 2x10's I'd buy as 16'ers, the first one on the outside is 8' long, then a 16. On the inside face start with a 16'er, this will distribute the breaks and help tie the building together. 

[ajbremer]

Thanks again Don_P!
You mentioned: "I'd use an old detail from the land grant college plans"...where can I find them and what are they for?