Do I need a permit for screen enclosure or pool cage in Smyrna?

Yes. In Georgia, screen enclosure or pool cage generally requires a permit, and Smyrna is no exception.

A screen room or patio cover attached to the house is a structure that generally needs a permit and setback review; a freestanding, non-roofed screen may be treated more lightly by some jurisdictions. Adding a roof cover can trigger structural, drainage, and (if enclosed) electrical review. Cobb County's own permitting office is the Cobb County Development and Inspections, reachable on 770-528-1000 at https://www.cobbcounty.gov/community-development/building-development/permitting. Its online permit portal is https://cobbca.cobbcounty.gov/CitizenAccess/default.aspx. It issues permits for the unincorporated county. If your city does not run its own building department, and many smaller Georgia municipalities do not, this is the office that will handle the job. An attached enclosure is a structural addition, so expect a plan review and a footing and attachment inspection. Smyrna's Residential Building Permit covers decks and porches, including replacements, and building additions, so a screened porch or enclosure is permitted work. Accessory structures and uses may not sit in a required front or side yard under Zoning Sec. 501.2, which limits where a detached screen room can go.