Digging post holes for pole barn

[UncleBuck1]

I'm about to start construction on a 36x48 monitor style pole barn. I had to special order the 24' poles for the center section and they're supposed to be ready for pickup in 3 weeks.

My site has been leveled and layout finalized and the next step is to drill 20 15" diameter holes for the posts. I'm planning to bury the posts 42" deep and I want to start out with 48" holes to allow for 6" of concrete under the post.

What has me stumped is whether I should buy a 3-point hitch auger or rent a skid steer with auger. A 3-point hitch auger would definately be a good investment and have other uses around my property, but I can't figure out whether it would have the ability to drill a 48" deep hole.

Can someone who's "been there/done that" give me some guidance on the right tool for this job?

 

[woodlandfarms]

I can't comment beyond what I know which is the skid steer version... 3 points generally do not have any downforce. A skidsteer does. If you have complicated soil the downforce is a good thing to have.

To get around this, you can get a hydrualic post hole digger (or build your own which is what I did), and attach it to your bucket. Then you have downforce. But it all goes to what kind of soil you are working on.

 

[AlanB]

Skidsteer auger (or dingo auger) are MUCH easier to use. not only for downforce (which is essential at times) but also for seeing what you are doing and ease of positioning.

A tractor auger is nice, but your neck and back will appreciate looking forward all day from a skidsteer or dingo.

48" is really deep. it would depend on the auger you have, but I believe most of mine are around 36" ish. you would need an extension. Generally you can dig all the way till the powerhead is at the ground surface. Measure the augers that you have available.

You will still need a manual post hole digger to get the bottoms clean. Buy the ones with the joint in the middle. You will need them to get that deep. Not to mention they are just a lot nicer in general.

 

[JimRB]

I did 12" holes for 6x6 poles using a tractor. I have a 4 foot mark on my manual post hole handles so I guess I cleaned up the holes down to 4 feet. I put gravel in the bottom of the hole and compacted it. The hope was it might drain. Probably not likely as the water table sometimes is higher than the bottom of the poles. By the way I did 38 holes. And another detail. I missed my mark on most holes so I was hand digging to get them in the correct place. Hand hoeing bags of Sakrete. It was a good way to spend a summer of weekends. I was stronger after all that digging and hoeing. No tractor to tip the 16 and 20 foot 6x6s.

 

[JimRB]

The second pole barn was just as big but we used trusses instead of 2x8 rafters so a lot less holes and I was not off my mark on the second barn. First barn was for horses. Second was for equipment.

 

[ENG18LT]

I just priced a 24" auger for my 3pt. post hole digger, $650.00. I can rent a skid steer with 24" auger for $355 including round trip delivery/pickup. No brainer there, I will be renting one. in a couple weeks as we are going to be starting a 50x40 monitor barn.

 

[CliffordK]

I just priced a 24" auger for my 3pt. post hole digger, $650.00. I can rent a skid steer with 24" auger for $355 including round trip delivery/pickup. No brainer there, I will be renting one. in a couple weeks as we are going to be starting a 50x40 monitor barn.

It all depends on what you need. A 24" diameter auger is a pretty big hole, and may only be used for things like pole barns or greenhouses. However, if you like wood fences, a smaller auger might be handy, so at least the post hold digger isn't wasted.

Are you pouring a concrete pad? Can you just add steel straps and sit the posts on top of the pad? Is the rot resistance better when sitting on a concrete pad?

 

[BeezFun]

Instead of pouring concrete under posts you can also use precast concrete pads called "pills". Standard sizes are 4" and 6" thick, with diameters 14-18". Especially nice if it's hard to get concrete to your site, and way cheaper.
If you have a lot of rocks, a 24" auger will be handy because the hole will bounce all over the place by the time you're done, and then you won't have to do any handshaving on the sides to get posts in the right location. If you're soil is rock free you might go with a 20". The bigger the hole the more backfilling you have to do.

 

[whistlepig]

About all the augers I have seen are 36" long. They do sell shaft extensions for the auger shafts. The problem that I had was that I didn't have a tractor with enough travel on the 3 point lift to go all the way to the bottom of a 48" deep hole and still be able to lift the auger high enough for the auger to clear the hole when done. I rented a skid loader with a 24" auger.

 

[SPIKER]

I would go bigger on the holes too, and use the pre-cast concrete cookies.

it is hard to get the holes aligned right and the bigger hole lets you/builder move the poles a bit not to mention getting a LONG pole into small hole can be hard.

Mark

 

[terry.dinerman]

I'm about to start construction on a 36x48 monitor style pole barn. I had to special order the 24' poles for the center section and they're supposed to be ready for pickup in 3 weeks.

My site has been leveled and layout finalized and the next step is to drill 20 15" diameter holes for the posts. I'm planning to bury the posts 42" deep and I want to start out with 48" holes to allow for 6" of concrete under the post.

What has me stumped is whether I should buy a 3-point hitch auger or rent a skid steer with auger. A 3-point hitch auger would definately be a good investment and have other uses around my property, but I can't figure out whether it would have the ability to drill a 48" deep hole.

Can someone who's "been there/done that" give me some guidance on the right tool for this job?

Save your money....rent a small excavator...you can then use the excavator as a hoist to help place and support the poles as you plumb them....

Terry

 

[Hickgtx600f4]

One idea for drilling your hole's for the poles is to rent a hand held/towable. worked great for me. only used a 10" hole. you can use two 1x4 boards nailed together in a V shape to guide your pole into the hole with out knocking the walls into the bottom of the hole. this is a pic of the begining of ours. 36'x48' and 6x6 poles 12' on center. instead of having to buy extra long 6x6's you can frame in a floor on your middle section and save some $$$ on the pole's.

 

[buckeyefarmer]

I was required to have 20" round footer under my posts, so I rented skidsteer with 18" auger and dug them a little bigger by hand. I set rebar in each hole so the tops of all footers were at the same height.

 

[QRTRHRS]

The skid steer will be easier and far faster. You may want to take a manual post hole digger and have a go at it to see how easy your soil digs. You are going to need to do some manual digging regardless of the auger method. As mentioned, augers that measure three feet will need an extention. Fifteen inches in diameter is alot for a three point in hard to dig soil. I have dug hundreds of nine inch holes usually to four feet but to five on occasion for posts with my 3pt and trust me, it is not fun especially if you have hard soil. Not to mention, if the three point jams, you need to take a four foot pipe wrench sometimes with a piece of pipe to unscrew it.

Still, if you have the need, a 3pt might be a consideration.

I agree that the precast concrete "pills" will do just fine over ready mix. Regardless of footing, tamp, tamp and tamp some more. Are you going to pour ready mix in around the posts? Lots of opinions on this. Some say the concrete accererates rot. I had a builder use this method in the past. He used the pads then poured around the posts. His theory was that since there was a "seam" between the pad and the concrete, that the water would be able to drain away. He had built many barns like this.

Good luck and have fun. Nothing like a new barn to warm the soul.

 

[UncleBuck1]

Thanks for all the information- looks like a skid steer rental is in my future! Also, it looks like I'm going to have 18" holes since rental place doesn't have a 15" auger.

I response to a couple of the questions, I've already ordered the 24' posts and they weren't that much more expensive than the shorter lengths that were in stock.

My strategy for the footings is to drill my holes to at least 48" and carefully pack/tamp the hole bottoms. Before I set the posts in the hole I'm going to nail a horizontal 2x4 brace 42" above the bottom of the posts; when I set them in the hole that will be hanging 6" above the bottom of the hole. Then its just a matter of pouring the concrete and tamping it thoroughly to make sure that it flows up under the bottom of the post. After all the posts are set I'm pouring a slab, so there will be approximately 4' of concrete supporting each post.

 

[djp1218]

renting is going to be the way for me to go also in the near future i need to dig 10 8in holes a min of 48in and im opting to rent a towable the guy at the rental place said it digs 4ft deep so i know im pushing it to the limit my job is just for a retaining wall so the 48 bucks a day is the cheapest way out if i was doiung a job as big as yours i would go with the skid steer also go luck with your prodject and dont forget to post pictures as you go

 

[Diamondpilot]

About all the augers I have seen are 36" long. They do sell shaft extensions for the auger shafts. The problem that I had was that I didn't have a tractor with enough travel on the 3 point lift to go all the way to the bottom of a 48" deep hole and still be able to lift the auger high enough for the auger to clear the hole when done. I rented a skid loader with a 24" auger.

I have a 1' shaft extension on my 12" auger. My 284 Jinma has no problem lifting it a good 10" above the ground and digs a honest 46" deep hole. I have built three barns, 2 decks, and drilled another 25 or so holes for well over 200 holes. I have only got it stuck once.

Chris

 

[Stimw]

Not sure why you want to concrete the posts, it seems like that will cause them to rot faster. ???
I went 4' with 6" X 6" X 20' posts and just set them on compacted dirt in my 40' X 50' pole building. I framed them with 2" X 4" at concrete level before I poured the concrete in case I ever need to replace them.
I would reccomend buying the strongest pesticide you can get and mix it with some old motor oil and paint the below grade areas before installing. Two or more coats as it soaks in.
If you can paint a mark on them so you know they are the right depth after standing them up. I helped a neighbor set his power pole. We painted a 5' mark and when stood up it was only 3 1/2' deep!!! We took a piece of PVC pipe and jetted it down to the 5' mark. It only took a couple minutes!

 

[UncleBuck1]

Not sure why you want to concrete the posts, it seems like that will cause them to rot faster. ???
I went 4' with 6" X 6" X 20' posts and just set them on compacted dirt in my 40' X 50' pole building.

Well, i know i need a (minimum) 15" dia. x 6" thick concrete footing under each post- hence my original question about drilling a 15" dia. hole 48" deep for post to be buried 42" deep (I hope that makes sense). To be honest, I haven't given much thought to backfill; looks like another issue I need to research!

 

[AlanB]

That will open a can of worms

I weld a pipe on the top of most my augers we use on the 3pt auger. Then I stick a bar or handle in it to back it out when stuck. If there are a lot of roots in the area (should not be where you are building) it is pretty essential to have some way of backing a 3 point auger up (big pipe wrench being most common)