In some areas, a building permit may be required prior to constructing a greenhouse. Most states don’t consider hobby greenhouses to be permanent structures, so in that case building permits are not required. However, there are particular cities and states in which your plans must first be approved before building can begin (this is especially true if you plan on laying any kind of foundation.) In this case it is better to be safe than sorry, so be sure to check locally before committing to your greenhouse project. Local contractors may be able to give you more information.