Zoning › State preemptions › Maine

Maine LD 2003 / 30-A M.R.S. §4358 — Affordable Housing 2.5x Density Bonus (ME)

Tracked preemption from the Maine overlay bundle.

Overview

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Effective
2023-07-01
Sunset
—
Authority
state
Scope
state:ME
Other Maine preemptions
Maine Short-Term Rental Framework — 30-A M.R.S. §4364 (2024 Amendments)Maine LD 2003 / 30-A M.R.S. §4364 — Statewide ADU MandateMaine LD 2003 / 30-A M.R.S. §4364-A — 2-4 Unit Middle Housing FloorMaine 30-A M.R.S. §4358(2) — Manufactured Housing ProtectionMaine Growth Management Act — Comprehensive Plan Consistency RequirementMaine 30-A M.R.S. §4326 — Growth / Rural / Transition Area Tripartite DesignationMaine Mandatory Shoreland Zoning Act — 38 M.R.S. §§435-449Maine Land Use Planning Commission — Unorganized Territory Zoning Authority
Primary-source summary
**Last reviewed**: April 2026 **Activity level**: High — LD 2003 (Public Law 2021 Ch. 672, effective July 1, 2023) imposed a statewide ADU mandate, 2-4 unit duplex-by-right in designated growth areas, and affordable-housing density bonuses. Maine has continued to amend the Growth Management Act and short-term-rental authority in the 131st and 132nd Legislatures (2023-2026). The Land Use Planning Commission (LUPC) remains the zoning authority of record across Maine's vast unorganized territory.

Trigger predicate

When this evaluates true for a parcel, the law's preempted fields take precedence over base zoning.

AND
  • city.has_zoning_ordinance == True
  • city.in_unorganized_territory == False
  • city.has_designated_growth_areas == True
  • parcel.in_designated_growth_area == True
  • project.affordable_pct ≥ 50

Preempted fields

3 fields on the base district schema are rewritten when the trigger fires.

FieldOpValueNote
base_districts[*].max_densitymultiply2.52.5x density bonus over base zoning district for developments with >=50% affordable units (per MaineHousing methodology)
base_districts[*].max_units_per_acremultiply2.5
base_districts[*].design_or_process_requirementswaive—Municipalities may not impose design/process requirements that substantively defeat the bonus

Citation

Authority source
30-A M.R.S. §4358; Public Law 2021 Chapter 672 (LD 2003)
§ §4358 (Affordable housing density bonus)
https://legislature.maine.gov/legis/statutes/30-A/title30-Asec4358.html

Research notes

Income-restriction methodology administered by Maine State Housing Authority (MaineHousing). Stacks with §4358(2) manufactured-housing protection. Applies only inside designated growth areas — municipalities without state-approved comp plan with growth-area designations are unaffected.