What do you mean by 'extra form up'? I'm in NC, Charlotte area. Footers are usually 24" wide and 20" deep. That trench 'is' the form to pour concrete.

Even if you do find a 16" bucket if your soil isn't perfect for digging it might end up being 18-24" in spots anyway. I just dug 500' with a 24" bucket on a mini-ex yesterday and there probably wasn't one spot that was 24" wide and especially wider when I hit hard pan/rocks.

Thanks for the reply's. This will be a monolithic slab and about a 75 yard pour. The min requirement in my area and at 3200 feet elev. is 12"W by 16"D which to me is to little. So I have increased it to 16"W by 20"D after talking to the local inspectors and some concrete finishers in the area. I have already moved hundreds of yards of dirt in order to build a barn and so far over 300' of driveway plus the house location. I have started to level an area to build and hit mostly small rocks, (football size). I have dug trenches as much as 6' deep and find that the trench size is maintained at my bucket width. I ran into two rocks weighing in at around 1000 lbs and getting them out did widen the trench. The photo below gives you the typical soil I'm dealing with, very good until it rains. Because of where we live and where we are building and time spent traveling back and forth as well as renting, we need to work efficient and not waste time. This will be my third house build, one being on an island off the coast of FL. having no bridges. We know how to get it right the first time.

I don't understand why you're not forming the footings. Around here, any foundation - even for a garage - is formed. Why would you not want a formed footing?

to dlm2000, I too have noticed that a lot of folks on here just use the dirt trench as their footing forms! Amazes me, as there's NO WAY my permit office would allow it. Everyone here makes wood forms for everything and strips them after the concrete cures a couple of days.

Such differences!