Detached accessory structures used as tool and storage sheds, playhouses or similar uses, provided the floor area does not exceed 256 square feet and is not more than one story, (under 18” floor height, under 10' eave height above grade.)
The quick and simple answer is: you usually don't need a permit if the shed is 120 square feet or less. In California, most jurisdictions have adopted the 120 square foot rule. If your shed area is larger than 120 square feet, it needs a building permit. If it's less than that, it doesn't.
A building permit is required for all new residential, commercial, and industrial construction – including alterations and equipment installations in Fairfax County.
On a single-family house, most routine work does not require a permit. You can: Paint, add or replace carpet, tile or hardwood floors, replace cabinets, and even replace paneling and drywall without a permit. Replace your windows and doors, as long as you don't change the size of the opening in the wall.
Permits are typically required for the following projects: alterations to existing commercial structures; commercial structures; carport enclosures; decks; demolition; electrical systems; finished basements; garages and sheds; HVAC systems; mobile homes; plumbing systems; pools, spas and hot tubs; renovations; ...
Various state regulations require contractors to pull permits. California, for example, mandates that anyone who works on your home must be licensed by the Contractors State Licensing Board (CSLB) if the project is over $500. Check the requirements where you live before starting your project.