Each state or municipality writes its own rules about when a building permit is needed. A job that requires a building permit in one place may not need it in another. Local conditions will affect whether or not you need a permit. If you live in "Tornado Alley" in the central United States, a building permit might be needed for a safe room or storm shelter, and such protection may be required by code.
New construction almost always requires a building permit, whether you're putting up a building or a major part of a building like a new addition [source: Barker]. These permits are also known as construction permits. They cover everything from the footings below the foundation to the roofing material overhead.
There are many other construction activities that require permits in most localities. For example, if you plan to install insulation or drywall in a large area, add or remove walls, or put in replacement windows, you will probably need a permit.
Any change of use, such as remodeling a garage into a living space, will call for a permit. And believe it or not, demolishing a structure often requires a building permit. Go figure.
Plenty of building projects are in a kind of gray area -- they may or may not need a permit. A deck may not need a permit if it's less than 30 inches (76.2 centimeters) from the ground [source: The Building Department]. A shed or gazebo might require a permit, but not if it's smaller than a certain size. Putting in a retaining wall might send you to get a permit if it's taller than 5 feet (1.5 meters), but you often don't need a permit to build a fence that's less than 6 feet (1.8 meters) high. Some towns require you to get a permit for new siding, some don't. In all of these cases, it's smart to check with your building department before you go ahead.
Plumbing, electrical and mechanical work is sometimes covered by a building permit and sometimes requires a separate permit. These permits may be issued only to licensed specialists like electricians or plumbers, and can cover anything from installing a new water heater to rewiring a kitchen. Work involving septic, air conditioning, irrigation and solar power systems usually needs a permit as well.
So, is there anything that doesn't need a permit? Fortunately, yes. Simple repairs, painting, wallpapering, new carpets, changing a faucet -- none of these requires a permit. If you replace a door with a similar door, you don't need a permit. Replacing window glass is OK, but replacing the window itself requires a permit [source: Barker]
Once you know you need one, actually getting a permit can seem like a big hassle. But as you'll find out in the next section, it's probably not as difficult as you think.