What can I do without a building permit?
The following section of the International Code describes the work that can be done without a building permit.

105.2 Work exempt from permit
Exemptions from permit requirements of this code shall not be deemed to grant authorization for any work to be done in any manner in violation of the provisions of this code or any other laws or ordinances of this jurisdiction. Permits shall not be required for the following: 

• Fences not over 6 feet high
• Movable cases, counters and partitions not over 5 feet, 9 inches in height
• Oil derricks
• One-story detached accessory structures used as tool and storage sheds, playhouses and similar uses, provided the floor area does not exceed 120 square feet
• Painting, papering, tiling, carpeting, cabinets, counter tops and similar finish work
• Prefabricated swimming pools accessory to a Group R-3 occupancy, as applicable in Section 101.2, which are less than 24 inches deep, do not exceed 5,000 gallons and are installed entirely above ground
• Retaining walls that are not over 4 feet in height, measured from the bottom of the footing to the top of the wall, unless supporting a surcharge or impounding Class I, II or III-A liquids
• Shade cloth structures constructed for nursery or agricultural purposes and not including service systems
• Sidewalks and driveways not more than 30 inches above grade and not over any basement or story below and which are not part of an accessible route
• Swings and other playground equipment accessory to detached one- and two-family dwellings
• Temporary motion picture, television and theater stage sets and scenery
• Water tanks supported directly on grade if the capacity does not exceed 5,000 gallons and the ratio of height to diameter or width does not exceed 2 to 1
• Window awnings supported by an exterior wall that do not project more than 54 inches from the exterior wall and do not require additional support of Group R-3, as applicable in Section 101.2, and Group U occupancies