Using a 24" Auger?

kantuckid · Oct 10, 2019

To save time and words I just posted in the thread herein "Auger Sizes" about PHD's, take a look/see there as well.

I have 9 pier holes to dig for a cabin foundation and now own a 12" PHD & bit. I can rent the big auger for $100 weekly and must drive a RT of 140k to pick it up then again for return. My tractor will spin it but I'm beginning to think a backhoe might make more sense.
Your thoughts please? and THANKS!

nyone · Oct 10, 2019

Why would you need a 24in auger for sono tubes? How big are your tubes? Even if there 16in you can prety easily make the hole bigger with a shovel.

Birdhunter1 · Oct 10, 2019

How big of a cabin are you building and what are you framing it with. A 6x6 post will sit on top of a 12" pier, a 24" pier i am guessing you are going to stack blocks? If so make your 12" hole and place a 16x16 box on top of the whole, plenty of rebar in the hole and inside the box for the small pad and call it good.
A 24" bit can put a good twist back into the machine, I would dig only a few inches and clean the bit out and be ready to kill the pto if you hit a root and it sucks in quick and hard.

rangerfredbob · Oct 10, 2019

I'm wondering similar. I bought a 24" bit and have a PHD to fit it on, but will my 26hp tractor be enough? As said above, was going to clear out often. If it's not, I can borrow a 50hp class tractor...

For the shop I'm going to build it is a pole barn and the plans call for 24" holes for the posts. Already had a PHD and found an auger bit for $125

kantuckid · Oct 10, 2019

I appreciate each one of these replies but I don't need engineering or construction advice.
The cabin is 16' x 20' w/8' porch. One of my sons is an licensed, civil engineer who calculated the wall loads for me. He does much larger projects than this one everyday. A wall load calculation is something I can do but he does it "faster than Dad"-HA!
FWIW, a 12" dia circle is 1/4th the surface area of a 24" circle. I've done decks using my 12" but given that I cannot get a redi-mix to this site, its piers.
The plan I've made is for 9 piers under the main walls with a 24" plastic base (I'll likely use "Redibase") holding a 10" sonotube. The building site is remote and off grid. I'll be mixing bag mix on a generator. No blocks involved. I have zero interest in digging the base holes with a shovel! Not gonna happen.
I'm soon to be 76 years old and happy I can build this thing. This one got designed while I was recovering form a hip replacement. Projects like this that I don't really need do float my boat in the end. :laughing:
This cabin is a 6" "D" log cabin with dovetail corners. It's not my first rodeo either, I am an experienced builder just shy on the 24" auger as I've fought with my 12" bit enough to be cautious.
Honestly, I'm leaning hard toward a backhoe as I'll be $200 in on a rental of a 24" auger.
Rangerfredbob, I can assure you there are lots of pole bldgs with less of a hole! I live in a rural eastern KY county with zero zoning and can do whatever I want to. The soil matters a lot, of course , but if you must build to a permit then your stuck with what the engineering tables say. Rocks are the looming question for you plus how deep.

rangerfredbob · Oct 10, 2019

I think it's 48" deep, but no rocks and no roots so I'm expecting smooth sailing... will probably just borrow my brothers bigger tractor since it has much more capacity on the 3pt... he used the auger to dig about 150 holes for tree starts but that was only a foot deep at most... In my area a permit is required as I'm not an actual farm...

BoylermanCT · Oct 10, 2019

Following as I am starting a pole barn next month that needs 14 18" holes dug 48" deep. Posts are triple 2x6 and set on 4"x16" precast concrete disks. I have access to a PHD with 12" auger. Looking at renting an 18" auger. Can a 28hp tractor dig 18" holes? I've never used a PHD on my tractor, but my FIL who owns the PHD has dug hundreds of holes with the 12" auger with his 29hp New Holland TC29D. Also have option to rent a hydraulic post hole digger and put it on a 8000lb Kubota mini excavator.

Kantuckid, keep us posted with regular pics.

nyone · Oct 11, 2019

The ease of how the auger digs and how many HP you need all depend on ground conditions. Since these things have no reverse like a hydraulic driven auger i bet you will either learn real quick on how not to let it screw in or get good at shoveling it out.

To the OP. I think your way over engineering this cabin with needing a 24in hole. Any how ask the PHD manufacture if its rated for a 24in auger. At $200 rental per day you can spend a bit more and rent a mini excavator.

kantuckid · Oct 12, 2019

I already knew the hp ratings for various augers from reading sales listings, etc..
As for $200, notice I said I'd be into $200 for a weeks rental @ $100/week plus a double RT to fetch the tool. It won't be my first PHD experience, just never used larger than what I've owned for many years.
Over engineering: Hmm. I suppose the engineering wall loads can be ignored and I've done it before but they are there for a reason, not something I dreamed up. I could do as the pioneers did and set it on rock piles. I can bet you this, the thousands of pole barn builders across the USA do what the build site and buyer allows per codes or not. I live in a zero code county other than an electrical or plumbing inspection some spots. This is off grid and on a farm so zero inspections. If one ignores the engineered wall load specs and I use my 12" auger, the number of piers quadruples from 9 to 4x9 = 36 holes with 12 auger. The larger holes save not only concrete but much labor as fewer tubes to fill. The cleaner worksite an auger provides vs. a backhoe/excavator is attractive too.
As said already, This soil is deep timber at the base of the ridge on a bench. For about 8-12" it's black forest soil then clay interspersed with sedimentary rocks/sandstone that fell down off the cliff above when dinos roamed. Some are big enough to be a problem. I suspect most holes would go OK though. it's not a spot where you'd plant trees using a 24" auger as in a tree nursery by any stretch!