The plan shall be drawn to scale and shall show actual dimensions and figures. All plans, specifications, and plot plans shall be signed by a licensed architect or a licensed professional engineer of the State of New Jersey, provided, however, that the owner of a single-family residence may sign the plans in the event he has prepared them and intends to occupy said premises and the owner shall file an affidavit to that effect with said plans. A plot plan, but only a plot plan, may be prepared and certified by a licensed land surveyor of the State of New Jersey.