I need to put in about 20 concrete footings for several deck-related projects. The footing base should be 12-18" (but see note below). Frost depth in my area requires footings to be 52" below grade (local building official has stated this).

Soil is clay with rocks, mostly 4-5" across (softballs). Based on past septic excavation, this seems to be pretty consistent.

I'm weighing how to best dig holes that deep. Local equipment rental options are:

Towable post-hole digger (up to 16" auger + extensions):

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Mini skid-steer (Dingo) with auger attachment (up to 16" auger + extensions):

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Mini-backhoe which claims 6' digging depth:

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In theory / "on paper" all of these could do the task. But it is hard to assess which will be the most effective at digging holes. By effective I mean:

  • Will work well in the soil

  • Dig a reasonably neat hole to requirements

  • Not take excessive time or labor

The rental cost for all is roughly the same or at least not a enough to be a primary concern.

I have some experience with small 3-point equipment on tractors and feel confident to safely learn & use these machines.

It is an option to do a larger # of smaller footings (meaning, smaller footprint & less load-bearing) if that makes any difference here. Though all things considered I'd think fewer, larger footings would be less overall work.

  • So, the soil is the same all the way down to depth? Any large rocks? That info will make a difference.
    – Solar Mike
    Commented Apr 16, 2019 at 9:38
  • @SolarMike thanks, I have added an update. It seems to be consistent based on past work. We've seen very few large rocks but smaller ones are numerous. Commented Apr 16, 2019 at 9:44
  • Have you considered using helical piles instead of digging?
    – Matthew
    Commented Apr 16, 2019 at 13:48
  • @Matthew yes and I am actually awaiting a quote for that. The anecdotal costs I've read about seem reasonable. Getting contractors to actually quote for things around here however is quite hard sometimes. Commented Apr 16, 2019 at 14:00
  • 1
    +1 for the dingo, 20 holes is a chore. let the hydraulics of the dingo do the lifting. And Dingo was its name-o!
    – Alaska Man
    Commented Apr 16, 2019 at 17:01

1 Answer 1


Having dug footings before by hand (2-man auger, clamshell digger and shovel) I would definitely suggest the Dingo for this project. I did 5 with the auger and 2 with clamshell (because it was near utility lines) but 20 footings is a lot and you should keep this simple and quick, letting the machine do most of the work.

Note- clamshell post-hole digger example:

enter image description here

A clamshell is not better than 2-man auger, it's a lot more work but you have to hand dig near utility lines. The 2-man auger has 4 handles and the motor in the middle, one man operates from one side and the other stabilizes as it digs. It's fast but it's a lot of exertion, especially for as many footings as you're talking about.

  • Thanks for clarifying, I understand now. The auger I'm considering is like a trailer, much bigger than a 2-man auger. But I don't know how it would compare to the Dingo. I agree a clamshell would be a huge PITA! :) (now that I know the term for it!) Commented Apr 16, 2019 at 13:13

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