hometips.gregvan.com The first step in planning your room addition is contacting the Planning Department. The second step would be to contact the Building Department. In this video, you will find out how important it is to contact your local building department, before you ever start any of your projects, including a room addition. The billing department can usually provide you with helpful pamphlets and guide you in the right direction, especially if you don’t have any experience dealing with these types of things.