Cumberland County, ME Accessory Structures: ADU Permits (2026)

There is no county building permit in Cumberland County. Each of the county's 28 municipalities maintains its own code enforcement office, which issues both the local zoning/land-use permit and the building permit required under the Maine Uniform Building and Energy Code (MUBEC, 25 MRS § 2451). MUBEC is mandatory in every Cumberland County municipality because all exceed the 4,000-population threshold under 25 MRS § 2373. An ADU application typically requires: (1) a site plan showing setbacks, the primary dwelling, and the proposed ADU footprint; (2) construction drawings meeting the 2015 IRC / 2021 IECC residential as adopted by Maine; (3) a subsurface wastewater disposal application (HHE-200) approved by the Maine DHHS-licensed Local Plumbing Inspector under 22 MRS § 42 if the property is on septic; (4) shoreland zoning review if within 250 ft of a protected waterbody under 38 MRS § 435 et seq. Under 30-A MRS § 4364-B, a municipality may not require any approval process for an ADU that is more burdensome than the process for a single-family dwelling. Maine state law (30-A MRS § 2691(3)) also requires municipal boards to issue a written decision within a reasonable time.