Do I need a permit for a shed in Portland, Maine?
Yes, but plan on a permit: Portland's building chapter requires one before you build any building or structure, with no small-shed exemption in the city text. In the residential neighborhood (RN) zones, a detached shed with a footprint of 250 sq ft or less needs only 5 feet from the rear line and 3 to 5 feet from the side lines, depending on the zone. Detached accessory buildings can be up to 18 feet tall.
| Permit | Required to construct any building or structure (no size exemption in city code) [1] |
| Rear setback, shed 250 sq ft or less (RN-1 to RN-6) | 5 feet [2] |
| Side setback, shed 250 sq ft or less | 5 ft (RN-1, RN-2, RN-5); 3 ft (RN-3, RN-4, RN-6) [3] |
| Rear setback, accessory building 250 sq ft or more | Same as the house: 25 ft (RN-1, RN-5), 20 ft (RN-2, RN-3), 10 ft (RN-4), 5 ft (RN-6) [4] |
| Max height, detached accessory structure | 18 feet in all RN zones [5] |
| Max lot coverage (residential uses) | 60% in RN-1 to RN-5; 100% in RN-6 [6] |
Permit
Chapter 6 says no one may start constructing, enlarging, altering, moving or demolishing "any building or structure" without a permit from the building authority [1]. Unlike many towns, Portland's ordinance text has no square-footage exemption for small sheds. The state building code may exempt small sheds from the building code itself, but you should still expect to file with Permitting & Inspections. If you start before getting a permit, the fee doubles.
Setbacks in residential zones
Table 7-A sets two tiers for detached accessory structures in the Residential Neighborhood zones (RN-1 to RN-6):
- Footprint 250 sq ft or less: 5 ft from the rear lot line in every RN zone [2], and 5 ft (RN-1, RN-2, RN-5) or 3 ft (RN-3, RN-4, RN-6) from the side lot lines [3].
- Footprint 250 sq ft or more: the same rear and side setbacks as the house. Rear setbacks run from 25 ft in RN-1 down to 5 ft in RN-6 [4]. Side setbacks follow Table 7-A: 8 ft in RN-1 and RN-2, 7 ft in RN-3, 5 ft in RN-4 and RN-6, and 16 ft in RN-5. RN-2, RN-3, RN-4 and RN-6 let one side be reduced (to 5, 4, 0 and 0 ft) if the two side yards together meet a minimum total.
The table has no separate front setback for accessory structures, so the zone's front setback for buildings applies.
Height and size
Detached accessory structures may be up to 18 feet tall in all RN zones [5]. Everything on the lot counts toward the maximum lot coverage: 60% for residential uses in RN-1 to RN-5, and 100% in RN-6 [6]. An accessory structure must be incidental and subordinate to the house in area, extent and/or use, and a lot may have more than one [7].
Other zones
Island zones (Table 7-B) and the business and mixed-use zones have their own dimensional tables. In the Shoreland Overlay Zone, structures must meet the shoreland setbacks from the water (see the Shoreland page). A detached ADU follows the small-structure side and rear setbacks no matter its size.
See how Portland compares with 8+ other Maine towns on sheds & accessory buildings →
Next steps
- Look up your zone on the Portland zoning map (most single-family homes are RN-1 through RN-5).
- Measure the shed footprint: 250 sq ft or less gets the small-structure setbacks (5 ft rear, 3-5 ft side); larger buildings must meet the house setbacks.
- Apply for a building permit with Permitting & Inspections (207-874-8703) with a plot plan showing the shed size, height and distances to lot lines.
- If you're in a historic district or the shoreland zone, ask whether extra review applies before you buy the shed.
Common questions
- Do I need a permit to build a shed in Portland, Maine?
- Plan on one. Portland requires a permit before building any building or structure, and the city text has no small-shed exemption. Starting before getting a permit doubles the fee.
- How far from the property line does a shed have to be in Portland, Maine?
- In RN zones, a detached shed of 250 sq ft or less needs 5 feet from the rear line and 3 to 5 feet from the side lines, depending on the zone.
- How tall can a shed be in Portland, Maine?
- Detached accessory structures can be up to 18 feet tall in all RN zones.
- What if my shed is bigger than 250 sq ft in Portland, Maine?
- A building of 250 sq ft or more must meet the same rear and side setbacks as the house. Rear setbacks run from 25 feet in RN-1 down to 5 feet in RN-6.
Maine building code and shoreland rules for sheds
Building code (MUBEC): The Maine Uniform Building and Energy Code adopts the 2021 International Residential Code, effective April 7, 2025. It must be enforced in towns with more than 4,000 residents. Smaller towns may choose to enforce it, but they can't adopt any other building code.
- Maine's version of the code says building permits are required "where required by municipal ordinance," and towns can exempt more work from permits.
- The residential code exempts small one-story detached accessory buildings from a building permit. Under the IRC that means up to 200 sq ft.
- Being exempt from a building permit doesn't exempt you from zoning. Setbacks, lot coverage and any land-use permit still apply. Check with your code officer.
Shoreland zone: A shed is a "structure" under the state shoreland rules, so it must meet the water setbacks: generally 100 ft from GPA great ponds and 75 ft from other waters and wetlands. It also counts toward the 20% lot-coverage cap. On a small nonconforming lot where a shed can't meet the setback, the code officer may allow one shed up to 80 sq ft and 8 ft tall, with no utilities. It has to be as far from the water as practical and never closer than the house.
What the ordinance says
- Sec. 6-92(a), Buildings and Building Regulations (Chapter 6) – incl. short-term rental registration, p. 6
(a) No person may commence work on any of the following without first obtaining a permit from the building authority: 1. Constructing, enlarging, altering, repairing, moving, converting, demolishing, or changing the use of any building or structure;
- Table 7-A, Rear setback (min.), Land Use Code (Code of Ordinances Chapter 14, ReCode), p. 116
Detached accessory structures 5 ft. 5 ft. 5 ft. 5 ft. 5 ft. 5 ft. (≤250 SF footprint)
- Table 7-A, Side setback, interior (min.), Land Use Code (Code of Ordinances Chapter 14, ReCode), p. 116
Detached accessory structures 5 ft. 5 ft. 3 ft. 3 ft. 5 ft. 3 ft. (≤250 SF footprint)
- Table 7-A, Rear setback (min.), Land Use Code (Code of Ordinances Chapter 14, ReCode), p. 116
Principal structures and detached accessory 25 ft. 20 ft. 20 ft. 10 ft. 25 ft. 5 ft.
- Table 7-A (cont.), Detached accessory structure height, Land Use Code (Code of Ordinances Chapter 14, ReCode), p. 117
Detached accessory structure 18 ft. 18 ft. 18 ft. 18 ft. 18 ft. 18 ft. height (max.)
- Table 7-A (cont.), Lot coverage (max.), Land Use Code (Code of Ordinances Chapter 14, ReCode), p. 117
Residential 60% 60% 60% 60% 60% 100%
- Article 3, Definitions (Structure, accessory), Land Use Code (Code of Ordinances Chapter 14, ReCode), p. 51
Structure, accessory. A structure on a lot that is incidental and subordinate in area, extent, and/or use to the principal structure on the lot. A lot may have more than one accessory structure.