So I am literally in the process of building a shop slash apartment upstairs as is described by so many of you. I went 40by100 with 17 ft eves. Apartment is just under 1600 sq ft, with kitchen two bedrooms and bath. I put a second bath downstairs directly under upstairs one (in the bar) HVAC in apartment. The lean to on the side is a great idea. Also pouring your pad a bit long on gable end is a plus, think patio. I am in process now of building the deck.