From St. Mary's County Code of Ordinances
Chapter 203, Section 105, PERMITS
105.1 Required.
Any owner or owner's authorized agent who intends to construct, move or demolish a building or structure, or to erect, install, or replace any electrical, gas, mechanical or plumbing system, the installation of which is regulated by this code, or to cause any such work to be performed, shall first make application to the Department and obtain the required 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:
Building:
1. One-story detached accessory structures used as tool and storage sheds, playhouses and similar uses, provided the floor area is not greater than 120 square feet and the structure is not located in the flood plain.