Maine Contractor Info
"General Contractors" are not regulated or licensed in the State of Maine.
Those who hire themselves out as a General Contractor, Home Builder, Construction Supervisor, etc, must still perform the work according to related local and State rules and act within the law or could wind up in legal trouble -- but Maine leaves in up to the consumer to find and hire a good contractor.
The State of Maine does requires licenses for several building related professions including "Home Improvement Contractors" as well Architects, Landscape Architects, Electricians, Plumbers, Oil & Gas Boiler Techs, etc.
Maine Contractor Related Professional License Information:
You can find official information on the State of Maine website for each type of contractor's license and check license status and, if needed file complaints
Door-to-Door Home Repair Sellers
Soliciting for Replacement Windows & Doors, Roofing, Solar Systems, Driveway Coating or other Home Repairs or Improvements "door to door" in Maine requires a Transient Seller of Home Repair Services License from the State for anyone who doesn't have permanent place of business in that town (or city). This protects consumers from criminals and scam-artists.
If you are a legitimate professional contractor, even if you have a job in a town, (lets say a roofing contract for a residential home), you can't send your crew walking around asking neighbors if they want their roof done "while we're in the neighborhood" unless you have a Transient Seller of Home Repair Services License.
A Maine State "Transient Seller of Home Repair Services" License is valid for the entire state. The cost is $51/yr, (License Fee: $30 plus $21 for a Maine State Police Criminal Background Check).
Architects, Landscape Architects and Interior Designers
In the State of Maine all Architects, Landscape Architects and Interior Designers must be licensed by the State Board of Licensure.
In the State of Maine all electricians must be licensed.
Manufactured Housing Professionals
The State of Maine requires that all manufactured housing professionals be licensed.
In the State of Maine all plumbers must be licensed.