Can I build an ADU in Cape Elizabeth, Maine?
Yes. Cape Elizabeth allows one accessory dwelling unit on any lot where a single-family home is the principal structure, inside the house, attached, or in a separate building. It can be no more than 1,200 sq ft (and smaller than the main home) and must meet a minimum size (190 sq ft in the ordinance, which defers to the state building codes board's standard, set at 160 sq ft in 2025); it can't be used as a short-term rental, and you need a building permit from the Code Enforcement Officer.
| Where allowed | Any lot where a single-family dwelling is the principal structure, including buildable nonconforming lots [1] |
| Attached vs detached | Within the house, attached, or a new/converted accessory structure [2] |
| Minimum size | 190 sq ft in the ordinance, unless the state building codes board adopts a different standard (which then applies) [4] |
| Maximum size | 1,200 sq ft and smaller than the primary dwelling (pre-2023 accessory-structure conversions exempt) [4] |
| Extra parking | None beyond the single-family home's requirement [3] |
| Short-term rental | Not allowed in an ADU [5] |
| Ownership | Same ownership as the main home (or a condominium under state law); no owner-occupancy rule found [6] |
| Permit | Building Permit from the Code Enforcement Officer [8] |
Where ADUs are allowed
An ADU is allowed on any lot where a single-family dwelling is the principal structure, including nonconforming lots where a single-family home could be built [1]. It is listed as a permitted accessory use in the Residence A, B and C districts, for example in Residence A [7]. One ADU per lot is the intent of the ordinance.
Attached or detached
You can create the unit within the existing home, attached to it, or as a new structure or a conversion of an existing accessory structure such as a garage [2]. An ADU in or attached to the house must meet the same setbacks as the house; an ADU in a garage or accessory structure that existed as of July 1, 2023 uses that structure's setbacks. The ADU is exempt from extra density or lot-size requirements.
Size, parking and ownership
The ordinance sets a 190 sq ft minimum but says that if the state Technical Building Codes and Standards Board adopts a different minimum, that standard applies; the state board set 160 sq ft in 2025, so confirm the current minimum with the town. The unit can be no larger than 1,200 sq ft and smaller than the primary home [4]. Converting an accessory structure that existed on January 1, 2023 is exempt from the maximum size. No extra parking is required beyond what the house needs [3]. The house and ADU must stay in the same ownership or be held as a condominium under the Maine Condominium Act [6]. We found no requirement that the owner live on the property.
Rental limits
An ADU may not be operated as a short-term rental [5]. Long-term rental is not restricted by this section.
Permits
No construction or enlargement may start until the Code Enforcement Officer issues a Building Permit [8], and an increase in the number of dwelling units needs a Certificate of Occupancy. If the ADU adds plumbing, a plumbing permit is needed before the building permit is issued. In the shoreland or Resource Protection areas, those district rules also apply.
See how Cape Elizabeth compares with 8+ other Maine towns on accessory dwelling units (adus) →
Next steps
- Confirm your lot's zoning district and that a single-family home is the principal structure.
- Measure the planned ADU floor area: no more than 1,200 sq ft and smaller than the main home, and at least the minimum the town currently applies (190 sq ft in the ordinance, or the state's 160 sq ft standard).
- Apply to the Code Enforcement Office (contact details at capeelizabeth.gov) for a Building Permit with a scaled site plan showing setbacks, plus a plumbing permit (and septic approval if on a private system).
- Get a Certificate of Occupancy from the Code Enforcement Officer before anyone moves in.
Common questions
- Can I build an ADU in Cape Elizabeth, Maine?
- Yes. Cape Elizabeth allows one accessory dwelling unit on any lot where a single-family home is the principal structure: inside the house, attached, or in a separate building. You need a building permit from the Code Enforcement Officer.
- How big can an ADU be in Cape Elizabeth, Maine?
- No more than 1,200 sq ft and smaller than the main home. The ordinance sets a 190 sq ft minimum but defers to the state building codes board's standard, set at 160 sq ft in 2025, so confirm the current minimum with the town.
- Can I use an ADU as a short-term rental in Cape Elizabeth, Maine?
- No. An ADU may not be operated as a short-term rental in Cape Elizabeth. Long-term rental isn't restricted by this section.
- Does an ADU need extra parking in Cape Elizabeth, Maine?
- No. No extra parking is required beyond what the single-family home needs. The page found no requirement that the owner live on the property.
Maine's statewide ADU law
Under 30-A M.R.S. §4364-B (first passed as LD 2003 in 2022), a town must allow at least one accessory dwelling unit (ADU) on a lot with a single-family home anywhere homes are allowed. Towns had to comply by 2024.
Rules in effect now:
- It can be inside the house, attached, or a new detached building.
- One ADU per lot is exempt from density limits.
- No extra parking can be required beyond what the house already needs.
- Setbacks are the same as for the house.
- Minimum size: the state building codes board set 160 sq ft in 2025. Towns may set a maximum size.
- Before you can move in, you must show the ADU has adequate water and septic/sewer.
- In the shoreland zone ADUs must meet shoreland rules, but towns can't ban them there outright.
- Sprinklers aren't required unless the ADU is in or attached to a building with more than 2 units.
Coming July 1, 2027 (LD 1829 of 2025, pushed back by LD 2173 in 2026): towns can no longer require the owner to live on the property, ADUs must also be allowed next to 2- and 3-unit buildings, and towns can't require planning board approval for an ADU. Towns may still regulate short-term rentals in ADUs. Private covenants and HOA rules can be stricter.
What the ordinance says
- Sec. 19-7-5(B)(1), Chapter 19 Zoning Ordinance (includes maps & appendices), p. 178
Single family Parity. An accessory dwelling unit shall be allowed on any lot where a single family dwelling is the principal structure, including nonconforming lots where a single family dwelling may be constructed.
- Sec. 19-7-5(B)(2), Chapter 19 Zoning Ordinance (includes maps & appendices), p. 178
An accessory dwelling unit may be constructed or established within an accessory structure subject to accessory structure setbacks.
- Sec. 19-7-5(B)(5), Chapter 19 Zoning Ordinance (includes maps & appendices), p. 179
Parking. An accessory dwelling unit shall not be subject to any additional motor vehicle parking requirements beyond the parking requirements of the single family dwelling unit on the lot where the accessory dwelling unit is located.
- Sec. 19-7-5(B)(6), Chapter 19 Zoning Ordinance (includes maps & appendices), p. 179
Size. An accessory dwelling unit must meet a minimum size of 190 square feet, unless the Technical Building Codes and Standards Board, pursuant to 10 M.R.S.A Sec. 9722, adopts a different minimum standard; if so, that standard applies. The accessory dwelling unit size shall not exceed 1,200 (one thousand two hundred) square feet and must be a smaller size than the primary dwelling unit. A conversion of an accessory structure that exists as of January 1, 2023 to an accessory dwelling unit shall be exempt from the maximum size.
- Sec. 19-7-5(B)(7), Chapter 19 Zoning Ordinance (includes maps & appendices), p. 179
Short Term Rental Prohibition. No accessory dwelling unit shall be operated as a Short Term Rental, Sec. 19-8-14, Short Term Rental Standards.
- Sec. 19-7-5(B)(8), Chapter 19 Zoning Ordinance (includes maps & appendices), p. 179
Ownership: The primary dwelling unit and the accessory dwelling unit shall be held in the same ownership or owned in compliance with the requirements of the Maine Condominium Act, 33 MRS Chapter 31.
- Sec. 19-6-1(B)(4) Residence A permitted accessory uses, Chapter 19 Zoning Ordinance (includes maps & appendices), p. 69
k. Accessory dwelling unit (Effective January 10, 2024)
- Sec. 19-3-2(C)(1), Chapter 19 Zoning Ordinance (includes maps & appendices), p. 36
Building Permit required. No construction, structural alteration, enlargement, or relocation of a building or structure shall commence until after the issuance of a Building Permit by the Code Enforcement Officer in accordance with Sec. 19-3-3, Building Permits.