Attached signs may be placed only on the side of a building facing a street and shall not project more than three inches from the face of the building, nor above the line of the eaves, and shall not obscure any window, door, or other architectural feature. In Residence Districts, the maximum area of signs shall not exceed three square feet for each permitted family or home occupation on residential premises, or 12 square feet for each permitted nonresidential premises. In any other district, the aggregate area of all signs on any face of a building fronting a street shall not exceed 10% of the area of that face or 30 square feet, whichever is smaller.