The following are excerpts from the 2015 International Building and Residential Codes for work that is exempt from a building permit. It is a much shorter to list work that does not require a permit versus for work that does need a permit;
Residential Work (1 and 2 Family units)
Commercial Work
If you still have questions, please call (573) 634-6410 and ask to talk with a building inspector.
For residential uses, a shed 200 square feet and smaller is exempt from a building permit.
With Commercial uses, a shed 120 square feet and smaller is exempt from a building permit.
With both Residential and Commercial, please check setbacks from the property lines. With a residential lot, a shed in the backyard should be 5 feet away from the rear and side property lines if it's more than 60 feet away from the front property line.
The following are links to copies of the Revised Missouri Statutes that define the practice of Architecture and Engineering. These also list instances of unauthorized practice prohibited - persons excepted.
Architects (3 pages)
Engineers (4 pages)
As a quick reference, new residential buildings that are 3 units or larger require an architect. Also, commercial building projects that involve 2,000 square feet or more require an architect.
For further information, please refer to the Missouri Division of Professional Registration for: Architects, Engineers, Land Surveyors and Landscape Architects
320 E McCarty St Jefferson City MO 65101 
573-634-6410
