Looking to borrow/rent an auger to dig 7 holes

[rockhound]

Most deck caisons only use sono tube if they're sticking out above ground. Unless your jurisdiction requires them you can do without.

this is no longer correct, code will read something like this depending on your county

there will be a frost line measurement 12-48 inches typically dependent on elevation etc. (this measurement is below undisturbed or natural soil) if you are digging into ground that was just left over from the excavation of your home then you will need to go deeper in some instances to reach "natural soil" because the uncompacted crap from the last excavation is not strong enough to hold a serious deck. for a deck that are foot off the ground it probably wouldn't matter, but the code does not necessarily take that into account.

the posts cannot contact the ground and typically must clear the grade by no less than 6 inches (this is where your tube comes into play) the concrete will raise the post above grade

the posts must be pressure treated

the post must have a post base that meets your county or city codes

the posts in this photo are done correctly and passed inspection last year:



there may be some places you can allow the post to contact the ground, but i am unaware of any location in colorado that would allow this anymore. maybe Phoenix