What the state's contractor page covers, and what it skips
On the Secretary of State's page for residential and general contractors, a license is required of contractors, defined as people who, for pay, perform or manage construction for an owner, subject to listed exceptions. Four license types are named: Residential-Basic, Residential-Light Commercial, General Contractor and General Contractor Limited Tier. The page adds that some specialty trades are outside the requirement, and so is work costing less than $2,500.
No Georgia page opened for this site says that water damage restoration, drying or mold work carries a state license of its own, and none says such work is exempt. Which license, if any, applies to a particular job is a question for the contractor and for the Secretary of State.
