ADU rules in Springfield

Springfield regulates ADUs in Section 4.7.120 of its zoning ordinance, and detached backyard units are expressly contemplated: the code caps 'New, detached, ACCESSORY DWELLING UNITS' at 20 feet in height and requires new detached ADU buildings to sit to the rear or side of the principal building. One ADU per lot is approved administratively through Tier 1 Administrative Site Plan Review, with no hearing. Two limits in the local text no longer bind a protected ADU: Section 4.7.123.A.1 confines ADUs to the Residence A and Residence A-1 districts, and Section 4.7.123.B.4 bars them on parcels under 5,000 square feet. M.G.L. c. 40A, Section 3 makes one ADU a by-right use in any single-family residential zoning district, which 760 CMR 71.02 defines as any district where single-family dwellings are permitted or allowable, and 760 CMR 71.03(3)(b)2 says a municipality 'may not require a minimum Lot size for a Protected Use ADU.'

The same section covers attached, internal and basement conversions. Springfield's Section 4.7.122 copies the state ADU definition word for word, so a unit whose separate entrance runs 'through an entry hall or corridor shared with the principal dwelling' qualifies, and Section 4.7.123.A.3 expressly contemplates 'Building expansions ... constructed for the purpose of creating an ACCESSORY DWELLING UNIT.' Section 4.7.124.D.4 exempts an ADU 'located within lawfully permitted existing dwelling, with no proposed expansion' from every dimensional rule in the section, so a straight interior or basement conversion faces only site plan review, the building code and the size cap. State law reinforces the point: 760 CMR 71.03(2)(e) bars a municipality from requiring that a protected ADU be either attached to or detached from the principal dwelling.

Springfield adopts the statutory floor and does not expand it. Section 4.7.124.D.1 caps an ADU at '1/2 the gross floor area of the principal dwelling or nine hundred (900) square feet, whichever is smaller,' identical to the definition in M.G.L. c. 40A, Section 1A. New detached ADUs may not exceed 20 feet in height, and ADUs in new or expanded accessory buildings must stand at least 10 feet from other buildings on the lot and 5 feet from the rear and side lot lines, outside the side yard setback that applies to the existing use in the underlying district. Interior conversions with no expansion escape all of those dimensional rules. Gross floor area is measured under 760 CMR 71.02, which counts basements of compliant ceiling height but excludes crawl spaces, garages, attics and enclosed porches.

Section 4.7.120 imposes no owner-occupancy or family-relationship condition, and none could be imposed. M.G.L. c. 40A, Section 3 provides that use of land or structures for a protected ADU 'shall not require owner occupancy of either the accessory dwelling unit or the principal dwelling,' and 760 CMR 71.03(2)(a) lists owner-occupancy as a prohibited regulation. Springfield does require common ownership: Section 4.7.123.B.3 says the principal building and the ADU 'shall remain in common ownership' and the ADU 'may not be sold separately from the principal building to which it is an accessory use.' That is a no-separate-sale rule rather than a live-on-site rule, so an absentee owner may build an ADU and rent both units.

Section 4.7.123.B.7 provides that an ADU 'must provide one (1) additional, on-site, accessible parking space,' and the submitted site plan has to show it. That flat requirement is lawful only where the lot lies entirely outside a half-mile radius of a transit station. 760 CMR 71.03(2)(b) bars a municipality from requiring more than one additional space when all portions of the lot are outside a 0.5 mile radius of a transit station, and from requiring any space at all when any portion of the lot falls inside that radius. 'Transit Station' covers subway stations, commuter rail stations, ferry terminals and bus stations, and EOHLC reads 'bus station' as 'a regular and specific location for pick-up and drop-off,' excluding flag stops. Springfield's ordinance carries no transit exception, so a homeowner near a qualifying stop has to invoke the state rule rather than the local text.

A single ADU is approved by staff, not by a board. Section 4.7.123 requires 'a Tier 1 Administrative Site Plan Review from the Office of Planning & Economic Development, prior to the issuance of a Building Permit,' which Table 4-4 confirms with the code '1' (use permitted subject to Administrative Site Plan Review). That review is non-discretionary: no public hearing is held, the office 'shall not deny approval of an application that meets all applicable requirements,' and if it fails to decide within 30 days approval is 'deemed constructively granted' and the applicant may seek a building permit 'in the same manner as for an AS OF RIGHT use.' A certificate of occupancy is required before the unit is used. A second ADU on the same lot needs a Tier 3 City Council special permit, which is exactly what 760 CMR 71.03(5) contemplates.

Long-term renting is the point of the section, whose stated purpose includes providing 'rental income for homeowners,' and 760 CMR 71.03(2)(c) bars any municipal restriction on who may occupy a protected ADU. Short-term rental is banned outright: Section 4.7.123.B.1 provides 'No ACCESSORY DWELLING UNIT shall be used for short-term rentals, as defined in City Ordinance, Chapter 238,' and Chapter 238 § 238-2 defines a short-term rental as occupancy 'for a period of fewer than 31 consecutive calendar days, in exchange for a fee, compensation, or payment of any kind,' expressly excluding month-to-month leases and tenancies at will. That prohibition is one of the few local restrictions state law clearly blesses, under M.G.L. c. 40A, Section 3 and 760 CMR 71.03(3)(c). The ADU also may not be sold separately from the principal building.