ADU rules in Saco

A detached backyard ADU is allowed by right alongside a single-family home. Saco's use table lists "Accessory dwelling unit (ADU)" as P (Permitted), never C (Conditional), in every residential district: Rural Conservation (RC), Low Density Residential (LDR), Seaside Residential (SR), West Residential (WR), Medium Density Residential (MDR), High Density Residential (HDR), Downtown (D), Main and Beach (MB), Highway Business (HB) and Camp Ellis (CE). Section 230-701(B) states that ADUs may be attached to or within the principal residence or detached and separate from it, with no more than one ADU per building lot. Detached units carry extra construction standards: a permanent foundation, use of the primary dwelling's existing access drive, visual compatibility with the principal residence, and a sprinkler or other Fire Department approved suppression system.

Attached and internal ADUs are allowed by right on the same terms as detached ones. Section 230-701(B) treats an attached ADU as an apartment accessory and subordinate to the principal single-family use, and § 230-701(E)(4), as amended 9-25-2023, provides that attached ADUs may be located anywhere within an existing or proposed single-family residential building so long as the applicable dimensional requirements are met, which covers basement, attic and addition conversions. The 2023 amendment also deleted the old rule (former § 230-701(E)(5)) that banned street-facing entrances for attached ADUs, so an attached unit's separate entrance may now face the street. Fire suppression is required for an attached ADU only where the existing residence already has it.

Section 230-701(E)(2) caps an ADU at 1,000 square feet of total floor area and sets a 400 square foot floor. The 9-25-2023 LD 2003 compliance ordinance raised the cap from 800 to 1,000 square feet, added the 400 square foot minimum, and deleted the old requirement that the principal residence itself be at least 900 square feet. There is no percent-of-primary-dwelling formula and no separate ADU height limit: under § 230-701(E)(1), new construction for an ADU simply has to meet the setback, lot coverage and building height requirements of the underlying district in Article IV, Table 4-1. Note that Saco's 400 square foot minimum is stricter than state law: 30-A M.R.S. § 4364-B(6) sets the ADU minimum at 190 square feet and authorizes municipalities to impose a maximum size, not a minimum.

Saco does not require the owner to live on the property, at application or on an ongoing basis. Section 230-701(B) makes Subsection E the exhaustive list of standards an ADU must meet, and Subsection E's ten paragraphs address size, foundation, location, driveway, design compatibility, utilities and fire protection only, with no occupancy condition anywhere in the section. The redline of the 9-25-2023 ordinance confirms the point: the only standard repealed in that round was the street-facing-entrance rule, not an occupancy rule. This is Saco's own choice rather than state preemption. The statewide ban on municipal owner-occupancy requirements, 30-A M.R.S. § 4364-B(4)(E), enacted by PL 2025, c. 385, § 17, does not apply to any Maine municipality until July 1, 2027, because PL 2025, c. 733, § 25 struck the earlier July 1, 2026 branch retroactively to September 24, 2025.

Table 10-1 in § 230-1001, as amended 9-25-2023, gives "Residential - accessory dwelling unit" its own row reading: use the existing parking required for the residential single-family use, with no additional parking spaces required for each ADU. In practice the lot still needs the 2 off-street spaces that a single-family dwelling requires, and the ADU adds nothing on top. This matches 30-A M.R.S. § 4364-B(4)(C), which has barred ADU-specific parking requirements since the mandate's implementation date of January 1, 2024 for municipalities like Saco whose ordinances are enacted by the municipal officers without voter approval.

Review is administrative. Section 230-701(F) requires only a building permit or certificate of occupancy from the City of Saco to build or create a legal ADU, and § 230-701(G) assigns administration and enforcement to the Saco Code Enforcement Office, whose Director may interpret the section flexibly. Table 3-3 marks ADUs P (Permitted), not C (Conditional), in every district where they are listed, so no conditional use hearing and no Planning Board approval is involved. Under § 230-1502(G) the Code Enforcement Officer must issue the permit or send a written notice of refusal within 10 calendar days; § 230-1502(F) requires the CEO to mail abutters notice within one week of issuing a permit that creates a new dwelling unit in a residential or shoreland district, which is a notification, not an approval step. Applications go through the Code Enforcement Department's online citizen portal or on paper at City Hall.

Section 230-701(D) is explicit: no ADU may be rented on less than a monthly basis, and short-term rentals of ADUs of less than one month in duration are prohibited. Renting the ADU to a long-term tenant is otherwise unrestricted, and the city's own ADU Guide notes that a homeowner may instead live in the ADU and rent out the primary residence, which likewise has to be rented for more than 30 days at a time. There is no ADU registration or licensing scheme. Saco's only rental licence is the Chapter 173 Seasonal Property Rental regime, which covers rentals of six days to four months and applies only to single-family, two-family and multifamily dwellings east of Seaside Avenue and Camp Ellis Avenue and within 400 feet west of those center lines; it requires a Code Enforcement Officer licence with a fire and life-safety inspection, bans per-day rentals and rentals shorter than six days, and expressly does not reach rentals longer than four months. An ADU cannot be sold separately from the main house: it stays on the same lot, and § 230-701(C) simply exempts it from the minimum-lot-area-per-dwelling-unit calculation rather than creating a separate parcel.