Accessory Structures in Portland, ME (2026)
9 verified accessory structures rules for Portland, Maine, sourced directly from the municipal code and official government pages.
Verified from official government sources
ADU Rules
Portland permits up to two accessory dwelling units (ADUs) per qualifying residential lot under Land Use Code Chapter 14 §6.6.2 (the December 2024 ReCode), implementing the statewide ADU mandate in 30-A MRS §4364-B.
ADUs Allowed by Right Per Portland Land Use Code §6.6.2
Few RestrictionsADU Permits
Any ADU — new construction, garage/basement/attic conversion, or detached accessory building — requires a building permit issued by Portland's Permitting and Inspections Department, plus separate electrical, plumbing, and mechanical trade permits.
ADU Building Permit Required from Portland Permitting & Inspections
Some RestrictionsADU Impact Fees
Portland does not impose a separate impact or development fee on ADUs; only the standard building permit fee under the Permitting and Inspections fee schedule (typically valued as a percentage of construction cost) plus connection charges for water and sewer apply.
No Citywide ADU Impact Fee — Building Permit Fees Apply Per Portland Fee Schedule
Few RestrictionsADU Owner Occupancy
Under Land Use Code §6.6.2, the owner of a Portland lot must occupy at least one of the dwelling units at the time an ADU is initially constructed or legally created, with a Peaks Island legally-nonconforming-lot exception.
Portland Requires Owner-Occupancy at Initial ADU Creation
Some RestrictionsADU Rental Restrictions
New ADUs in Portland are exempt from the city's non-owner-occupied short-term rental registration cap for the first 5 years after construction, after which they revert to the normal STR waitlist under the Chapter 6 STR ordinance.
ADUs Exempt from Short-Term Rental Cap for First 5 Years Post-Construction
Some RestrictionsShed Rules
Sheds 200 sq ft or smaller are exempt from a MUBEC building permit but still require zoning/land-use review for setbacks and lot coverage; sheds over 200 sq ft require a full building permit from the Permitting and Inspections Department.
Sheds and Detached Accessory Structures
Some RestrictionsGarage Conversions
Converting a garage to living space requires a building permit and zoning review; garages may also be converted into an Accessory Dwelling Unit (ADU), with detached ADUs above a garage allowed up to 25 ft in height under the 2024 ReCode Land Use Code.
Garage Conversions and ADU Garage Conversions
Some RestrictionsCarport Rules
Carports are regulated as detached covered accessory structures under the Portland Land Use Code: a building permit is required for any roofed structure regardless of size, and the carport must meet residential setbacks (3-5 ft side/rear under ReCode) and lot-coverage limits.
Carports and Detached Covered Parking Structures
Some RestrictionsTiny Homes
Portland allows fixed-foundation tiny homes that comply with MUBEC as either a primary dwelling or an ADU (subject to a 190 sq ft state minimum and Portland's ADU rules); tiny houses on wheels are treated as recreational vehicles and cannot be used as permanent dwellings on residential lots.
Tiny Homes and Tiny Houses on Wheels
Heavy RestrictionsLooking for Cumberland County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Portland city rules.
Accessory Structures in Cumberland County →