It is unlawful to vary materially from the approved plans and specifications deposited with and approved by the building inspector unless amended plans and specifications showing such proposed alteration or variation are first submitted to the building inspector, in duplicate and duly approved by him, and if such alteration or variation will result in an increase in the total cost of the work, a statement to this effect shall be made on such additional plans and the necessary additional fee shall be paid. (Prior code § 5-1-5)