[Any work requiring a permit in Use Groups R-2, R-3, and R-4 would necessitate a Certificate of Use and Occupancy Inspection for these structures.] The Commonwealth of Pennsylvania's universal building code specifies the following: SS 403.61. Residential structures. (a) Height requirements. All residential buildings shall be at least 2 stories high and not exceed 6 floors if all habitable rooms are on one floor or not exceed 4 floors if most habitable rooms are on more than 1 floor. Where stairs provide access to more than one floor, they must be wide enough for a person to go up or down them safely. In no case shall steps be allowed to protrude beyond the face of the building. So, no, it is not necessary to obtain a certificate of occupancy from your local building department before you can legally build in Pennsylvania. However, the law does require certain types of construction (such as use of scaffolding or lifts), so make sure to read all the rules associated with your project to ensure you comply with them.