We are planning to build a detached garage/workshop (24×30, simple gable w/ 12′ top plate) across the driveway from our house on the only available flat spot on the property not otherwise used or tree-covered.  This spot makes a little knob on the side of a hill, and was spot was created when the previous owners did some unpermitted grading, and consists of uncompacted fill and a couple of boulders.  Even worse, our native soils are highly expansive clay.  So, according to our soils engineer, we basically have to dig out and rebuild that little knob before we can use it.  He is recommending a minimum footing embedment depth of 2 feet, and we have to have 10 feet horizontal from the bottom of the footing to daylight at the face of the hillside.  In order to get that 10 feet to daylight, I’ll either have to push the slope out 2′ futher than it currently is (more fill), or go with a 3′ deep footing.  I’m thinking that the deeper footing is the better and less expensive idea (also concerned with the amount of grading triggering a Minor Use Permit requirement), but would be interested in feedback from eperienced folks out there.