A building permit is generally necessary for any work unless explicitly exempted by the Building Code. Detached ancillary buildings, such as sheds and playhouses, that are less than 100 square feet are normally exempt from permission requirements. However, if these structures are located within 25 feet of a property line or visible roofline, they must be approved by the building department. The building official will determine if your project requires a permit based on its size, location, and type. For example, if you plan to build a garage/workshop on your property, you will need to obtain a building permit. If you want to add a room to your house without first getting a permit, you might be able to get an exception from the zoning administrator. The building official can grant exceptions under certain conditions; for example, if another structure on the site received approval without a permit then one more similar in size would not require one itself. Building permits cost between $150 and $200, depending on the size of the project. Fees include processing fees ($10-15) for telephone calls to verify information about your project (such as floor plans), inspections during construction (usually free but sometimes with a charge), and post-construction visits by the inspector (usually free). In most cases, building permits are required before you can start work.