Digging footing holes with a clamshell digger is quick and inexpensive, but makes sense only if you need a few shallow holes in loamy soil. For most every other installation, rent a machine to make the work easier. You have two choices—either a one-person or two-person auger. Both machines have advantages and disadvantages. The one-person is counterweighted to make it easier to raise the bit out of the hole. But it's more expensive. A two-person auger is less expensive and easier to move around, but is less powerful and you must lift the bit out of the hole yourself.
There are 5 steps to completing this project:
Before you start digging, be sure to check with your local utility companies to make sure there aren’t any underground lines.
Remove the layout lines and the spike marking the centre of the footing. Start the hole with the bit extension that will keep the handles about waist-high. Rock the tool slightly as its auger turns. When you reach the proper depth, rock the auger with the bit at the bottom of the hole to flare the base of the footing.
Remove any loose soil either by hand or with a clamshell digger and tamp a layer of compactible gravel to the code-required thickness (usually 3–6 inches). Use a post, tamper or pinch bar to compact the gravel.
Install a footing base in the bottom of the hole and cut the tube form to length. Level the top of the form so the footing will be level when you pour it.
Brace the tube in place to make certain it stays level. If the form shifts slightly from centre, don't worry. You just need to make sure the post base is centred when you make the pour.
Backfill around the form but don't tamp the dirt too much. This may distort the shape or shift the position of the form. If the footing hole is significantly larger than the form, wait to backfill until you’ve poured the concrete. Otherwise the dirt will fill the flared portion of the hole.
