Only your local building department can tell you for sure. This is normally an agency within the city or county government. Call them and let them know the size and type of structure you are planning on building.
Smaller hobby style greenhouses (under 120 square feet) typically do not require building permits. If a permit is required you also might have to provide a certified engineering drawing to the building officials before you can obtain one. If required, we can supply, for an additional charge, certified engineering prints and calculations for most of our greenhouses.
Note: It is important that this be done prior to ordering the structure. You alone are responsible to make sure that you are building in accordance with your local codes.