APPROVED CHAPTER
JUNE 20, 2025 385
BY GOVERNOR PUBLIC LAW
STATE OF MAINE
_____
IN THE YEAR OF OUR LORD
TWO THOUSAND TWENTY-FIVE
_____
H.P. 1224 - L.D. 1829
An Act to Build Housing for Maine Families and Attract Workers to Maine
Businesses by Amending the Laws Governing Housing Density
Be it enacted by the People of the State of Maine as follows:
Sec. 1. 25 MRSA §2463-B is enacted to read:
§2463-B. Fire protection in accessory dwelling units
Fire suppression sprinklers are not required for an accessory dwelling unit unless the
accessory dwelling unit is within or attached to a structure of more than 2 dwelling units,
including accessory dwelling units. As used in this section, "accessory dwelling unit" has
the same meaning as in Title 30-A, section 4301, subsection 1-C.
Sec. 2. 30-A MRSA §4301, sub-§1-C, as enacted by PL 2019, c. 145, §1 and
reallocated by RR 2019, c. 1, Pt. A, §36, is amended to read:
1-C. Accessory dwelling unit. "Accessory dwelling unit" means a self‑contained
dwelling unit located within, attached to or detached from a single-family dwelling unit or
multi-unit structure located on the same parcel of land.
Sec. 3. 30-A MRSA §4360, sub-§2, as enacted by PL 2003, c. 127, §1, is amended
to read:
2. Differential ordinances. A municipality may enact rate of growth ordinances that
set different limits on the number of building or development permits that are permitted in
designated rural areas and designated growth areas. A municipality may not enact rate of
growth ordinances that limit residential development in designated growth areas, as defined
in section 4301, subsection 6-C, except as authorized by this chapter.
Sec. 4. 30-A MRSA §4364, sub-§2, as enacted by PL 2021, c. 672, §4, is amended
to read:
2. Density requirements. A municipality shall allow an affordable housing
development where multifamily dwellings are allowed to have a dwelling unit density of
at least 2 1/2 times the base density that is otherwise allowed in that location and may not
require more than 2 off-street parking spaces for every 3 units. The development must be
in a designated growth area of a municipality consistent with section 4349‑A, subsection
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1, paragraph A or B as identified in a comprehensive plan adopted pursuant to this
subchapter or the development must be served by a public, special district or other centrally
managed water system and a public, special district or other comparable sewer system. The
development must comply with minimum lot size requirements in accordance with Title
12, chapter 423‑A, as applicable.
Sec. 5. 30-A MRSA §4364, sub-§2-A is enacted to read:
2-A. Additional height allowance. Except as otherwise prohibited under Title 38,
chapter 3 and municipal shoreland zoning ordinances, a municipality shall allow, subject
to review by a municipal fire official or designee, an affordable housing development to
exceed any municipal height restriction by no less than one story or 14 feet.
Sec. 6. 30-A MRSA §4364, sub-§5, as enacted by PL 2021, c. 672, §4 is amended
by enacting at the end a new first blocked paragraph to read:
Upon receipt of written verification from a local plumbing inspector that a housing
structure meets the requirements of this subsection, additional review or documentation by
a municipality related to waste and wastewater requirements before issuing a certificate of
occupancy is prohibited.
Sec. 7. 30-A MRSA §4364-A, sub-§1, as amended by PL 2023, c. 192, §6, is
repealed and the following enacted in its place:
1. Use allowed. Notwithstanding any provision of law to the contrary, except Title
12, chapter 423‑A, for any area in which residential uses are allowed, including as a
conditional use, a municipality shall allow at a minimum:
A. Three dwelling units, attached or detached, including accessory dwelling units, per
lot; and
B. Four dwelling units, attached or detached, including accessory dwelling units, per
lot if the lot is located in a designated growth area, as identified in a comprehensive
plan adopted pursuant to this subchapter, or served by a public, special district or other
centrally managed water system and a public, special district or other comparable sewer
system.
A municipality may allow more units than the minimum number required by this
subsection.
Sec. 8. 30-A MRSA §4364-A, sub-§2, as amended by PL 2023, c. 192, §8, is
repealed.
Sec. 9. 30-A MRSA §4364-A, sub-§2-A is enacted to read:
2-A. Lot size and density allowance for private property. Notwithstanding any
provision of law to the contrary, except Title 12, chapter 423‑A, this subsection applies to
any area in which residential uses are allowed, including as a conditional use.
A. If a lot is located in a designated growth area and is served by a public, special
district or other centrally managed water system and a public, special district or other
comparable sewer system, a minimum lot size requirement may not exceed 5,000
square feet and a density requirement may not exceed 1,250 square feet of lot area per
dwelling unit for the first 4 dwelling units and 5,000 additional square feet of lot area
per dwelling unit for subsequent units.
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 B. If a lot is located outside a designated growth area and in an area served by a public,
special district or other centrally managed water system and a public, special district
or other comparable sewer system, a minimum lot size requirement may not exceed
5,000 square feet and a density requirement may not exceed 5,000 square feet of lot
area for the first 2 dwelling units contained within a single structure, not including
accessory dwelling units.
C. If a lot is located in a designated growth area without a public, special district or
other comparable sewer system, a minimum lot size requirement may not exceed the
minimum lot size required by Title 12, chapter 423‑A and the density requirement or
calculation may not be more restrictive than required by Title 12, chapter 423‑A.
If 4 or fewer dwelling units have been constructed on a lot as a result of the allowances
under this section or section 4364‑B, the lot is not eligible for any additional increases in
density, including under section 4364, unless more units are allowed by the municipality.
Sec. 10. 30-A MRSA §4364-A, sub-§3, as amended by PL 2023, c. 192, §9, is
repealed and the following enacted in its place:
3. General requirements. Except as provided in this section, a municipal ordinance
may not establish dimensional requirements for multiple units allowed by this section that
are greater than dimensional requirements required for single-family dwelling units. As
used in this subsection, "dimensional requirements" means requirements that govern the
size and placement of structures, including building height, lot area, minimum frontage, lot
depth and setbacks.
Sec. 11. 30-A MRSA §4364-A, sub-§4, as enacted by PL 2021, c. 672, §5, is
amended by enacting at the end a new first blocked paragraph to read:
Upon receipt of written verification from a local plumbing inspector that a housing
structure meets the requirements of this subsection, additional review or documentation by
a municipality related to waste and wastewater requirements before issuing a certificate of
occupancy is prohibited.
Sec. 12. 30-A MRSA §4364-A, sub-§5-A is enacted to read:
5-A. Planning board approval not required. A municipality may not require
planning board approval for 4 or fewer dwelling units within a structure.
Sec. 13. 30-A MRSA §4364-B, sub-§1, as amended by PL 2023, c. 192, §12, is
further amended to read:
1. Use permitted. Except as provided in Title 12, chapter 423‑A, a municipality shall
allow an accessory dwelling unit to be located on the same lot as a single-family dwelling
unit or multi-unit structure in any area in which residential uses are permitted, including as
a conditional use, in accordance with this section.
Sec. 14. 30-A MRSA §4364-B, sub-§2, ¶B, as enacted by PL 2021, c. 672, §6, is
amended to read:
B. Attached to or sharing a wall with a single-family dwelling unit or multi-unit
structure; or
Sec. 15. 30-A MRSA §4364-B, sub-§3, as amended by PL 2023, c. 192, §15, is
further amended to read:
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 3. Zoning requirements. With respect to accessory dwelling units, municipal zoning
ordinances must comply with the following conditions:
A. At least one accessory dwelling unit must be allowed on any lot where a single-
family dwelling unit is the principal structure; and
B. If more than one accessory dwelling unit has been constructed on a lot as a result
of the allowance under this section, the lot is not eligible for any additional increases
in density except as allowed by the municipality; and
C. An accessory dwelling unit is must be allowed on a lot that does not conform to the
municipal zoning ordinance if the accessory dwelling unit does not further increase the
nonconformity.
Sec. 16. 30-A MRSA §4364-B, sub-§4, ¶A, as enacted by PL 2021, c. 672, §6, is
amended to read:
A. A municipality shall exempt an one accessory dwelling unit on a lot from any
density requirements or calculations related to the area in which the accessory dwelling
unit is constructed.
Sec. 17. 30-A MRSA §4364-B, sub-§4, ¶E is enacted to read:
E. A municipality shall allow the construction or occupancy of an accessory dwelling
unit on a lot even if the owner of the lot where the accessory dwelling unit is located
does not reside in a dwelling unit on that lot.
Sec. 18. 30-A MRSA §4364-B, sub-§7, as enacted by PL 2021, c. 672, §6, is
amended by enacting at the end a new first blocked paragraph to read:
Upon receipt of written verification from a local plumbing inspector that a housing
structure meets the requirements of this subsection, additional review or documentation by
a municipality related to waste and wastewater requirements before issuing a certificate of
occupancy is prohibited.
Sec. 19. 30-A MRSA §4364-C, sub-§4 is enacted to read:
4. Mandatory training. The municipal reviewing authority and the municipal body
hearing zoning appeals, if applicable, shall attend a training on land use planning offered
by a state agency or a statewide association representing municipalities or a regional
council or municipality within 180 days of appointment or, if a training is not available
within the 180-day period, the municipal reviewing authority member and the municipal
body hearing zoning appeals must attend the next available training.
Sec. 20. 30-A MRSA §4401, sub-§4, as amended by PL 2023, c. 79, §1, is further
amended to read:
4. Subdivision. "Subdivision" means the division of a tract or parcel of land into 3 or
more lots within any 5-year period that begins on or after September 23, 1971. This
definition applies whether the division is accomplished by sale, lease, development,
buildings or otherwise. The term "subdivision" also includes the division of a new structure
or structures on a tract or parcel of land into 3 5 or more dwelling units within a 5-year
period, the construction or placement of 3 5 or more dwelling units on a single tract or
parcel of land and the division of an existing structure or structures previously used for
commercial or industrial use into 3 5 or more dwelling units within a 5-year period.
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A. In determining whether a tract or parcel of land is divided into 3 or more lots, the
first dividing of the tract or parcel is considered to create the first 2 lots and the next
dividing of either of these first 2 lots, by whomever accomplished, is considered to
create a 3rd lot, unless:
(1) Both dividings are accomplished by a subdivider who has retained one of the
lots for the subdivider's own use as a single-family residence that has been the
subdivider's principal residence for a period of at least 5 years immediately
preceding the 2nd division; or
(2) The division of the tract or parcel is otherwise exempt under this subchapter.
B. The dividing of a tract or parcel of land and the lot or lots so made, which dividing
or lots when made are not subject to this subchapter, do not become subject to this
subchapter by the subsequent dividing of that tract or parcel of land or any portion of
that tract or parcel. The municipal reviewing authority shall consider the existence of
the previously created lot or lots in reviewing a proposed subdivision created by a
subsequent dividing.
C. A lot of 40 or more acres must be counted as a lot, except:
(2) When a municipality has, by ordinance, or the municipal reviewing authority
has, by regulation, elected not to count lots of 40 or more acres as lots for the
purposes of this subchapter when the parcel of land being divided is located
entirely outside any shoreland area as defined in Title 38, section 435 or a
municipality's shoreland zoning ordinance.
D-1. A division accomplished by devise does not create a lot or lots for the purposes
of this definition, unless the intent of the transferor is to avoid the objectives of this
subchapter or avoid other applicable municipal requirements, including, but not limited
to, road standards and safety.
D-2. A division accomplished by condemnation does not create a lot or lots for the
purposes of this definition, unless the intent of the transferor is to avoid the objectives
of this subchapter.
D-3. A division accomplished by order of court does not create a lot or lots for the
purposes of this definition, unless the intent of the transferor is to avoid the objectives
of this subchapter.
D-4. A division accomplished by gift to a person related to the donor of an interest in
property held by the donor for a continuous period of 5 years prior to the division by
gift does not create a lot or lots for the purposes of this definition, unless the intent of
the transferor is to avoid the objectives of this subchapter. If the real estate exempt
under this paragraph is transferred within 5 years to another person not related to the
donor of the exempt real estate as provided in this paragraph, then the previously
exempt division creates a lot or lots for the purposes of this subsection. "Person related
to the donor" means a spouse, parent, grandparent, brother, sister, child or grandchild
related by blood, marriage or adoption. A gift under this paragraph can not cannot be
given for consideration that is more than 1/2 the assessed value of the real estate.
D-5. A division accomplished by a gift to a municipality if that municipality accepts
the gift does not create a lot or lots for the purposes of this definition, unless the intent
of the transferor is to avoid the objectives of this subchapter.
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D-6. A division accomplished by the transfer of any interest in land to the owners of
land abutting that land does not create a lot or lots for the purposes of this definition,
unless the intent of the transferor is to avoid the objectives of this subchapter. If the
real estate exempt under this paragraph is transferred within 5 years to another person
without all of the merged land, then the previously exempt division creates a lot or lots
for the purposes of this subsection.
E. The division of a tract or parcel of land into 3 or more lots and upon each of which
lots permanent dwelling structures legally existed before September 23, 1971 is not a
subdivision.
F. In determining the number of dwelling units in a structure, the provisions of this
subsection regarding the determination of the number of lots apply, including
exemptions from the definition of a subdivision of land.
H-2. This subchapter may not be construed to prevent a municipality from enacting an
ordinance under its home rule authority that otherwise regulates land use activities.
A municipality may not enact an ordinance that expands the definition of "subdivision"
except as provided in this subchapter. A municipality that has a definition of
"subdivision" that conflicts with the requirements of this subsection at the time this
paragraph takes effect shall comply with this subsection no later than January 1, 2021
July 1, 2027. Such a municipality must file its conflicting definition at the county
registry of deeds by June 30, 2020 for the definition to remain valid for the grace period
ending January 1, 2021. A filing required under this paragraph must be collected and
indexed in a separate book in the registry of deeds for the county in which the
municipality is located.
I. The grant of a bona fide security interest in an entire lot that has been exempted from
the definition of subdivision under paragraphs D‑1 to D‑6, or subsequent transfer of
that entire lot by the original holder of the security interest or that person's successor
in interest, does not create a lot for the purposes of this definition, unless the intent of
the transferor is to avoid the objectives of this subchapter. A mortgage, pledge or other
instrument of hypothecation against a dwelling unit or other smaller portion of real
property within a parcel that is otherwise defined by this section as a lot does not itself
constitute a subdivision for purposes of this section.
J. Unless the intent of a transferor is to avoid the objectives of this subchapter, the
division of a tract or parcel of land accomplished by the transfer of any interest in the
land to a holder does not create a lot or lots for purposes of this definition if:
(1) The transferred interest, as expressed by conservation easement, binding
agreement, declaration of trust or otherwise, is to be permanently held for one or
more of the following conse