Abington · Plymouth County

Can you build an ADU in Abington?

Abington took the ADU question to its annual town meeting on 7 April 2025 and adopted a protected use bylaw into Chapter 175. The zoning itself is unremarkable. What decides projects here is the overlay: a large part of the town sits in a Watershed Protection District with its own septic flow and impervious surface caps, and those bind before the zoning does.

What the state guarantees you

Since 2 February 2025 this applies in every Massachusetts community. A town may be more generous than this. It may not be less.

Rule	What it means
Allowed by right	One ADU in single-family zoning districts, statewideNo special permit and no public hearing for a protected-use ADU
Maximum size	900 sq ft, or 50% of the principal dwelling, whichever is smallerA town may allow larger. It cannot allow smaller
Owner occupancy	A town cannot require itSo you may rent both units, or live in the ADU and rent out the house
Parking	One space at most, and none at all within half a mile of transitA town cannot ask for more than this
Short-term rental	The state leaves this to each townAll six towns documented here ban it, and two of them ban it for the main house too
In force since	2 February 2025Any conflicting local zoning became unenforceable that day

What Abington adds on top

Rule	In Abington
Adopted	Annual Town Meeting, 7 April 2025, into Chapter 175
Where allowed	By right in R-20 high density, R-30 medium density and R-40 low density residential, per the use regulations at Section 175-21
Forms permitted	Detached, attached and interior conversion
Maximum size	900 sq ft or 50% of the principal dwelling, whichever is smaller
Dimensional rules	Section 175-29, the dimensional and density table, reported to cap height at 35 ft
Detached setbacks	Section 175-26 governs detached accessory buildings
Watershed overlay	Section 175-24. Impervious surface capped at 15% of lot area or 2,500 sq ft, whichever is greater
Watershed septic cap	110 gallons per day of design flow per 10,000 sq ft of lot area, which on a smaller lot can bind tighter than Title 5 alone
Floodplain	Section 175-35, referencing the Plymouth County flood insurance study dated 3 July 2024
Who to ask	Abington Planning Department, 781-982-0069

The overlay is the thing to check first, and it is checkable before you make an offer. Ask which zoning district the lot sits in, then ask whether it falls inside the Watershed Protection District. If it does, and the property is on septic, the 110 gallons per day per 10,000 sq ft of lot area figure sets a ceiling on total design flow across the house and the new unit together. On a 20,000 sq ft lot that is 220 gallons a day for everything, and a bedroom carries a design flow whether anyone sleeps in it or not, so an existing four-bedroom house can consume the allowance before the ADU is drawn. The impervious cap works the same way against a driveway, a parking space and a roof. Neither figure appears in the ADU bylaw. Both will still stop the project.

Questions people ask

Which Abington districts allow an ADU?

R-20, R-30 and R-40 residential districts allow detached, attached and interior conversion accessory dwelling units by right, under the use regulations at Section 175-21. The bylaw was adopted at the annual town meeting on 7 April 2025.

How big can an Abington ADU be?

900 square feet or 50% of the principal dwelling, whichever is smaller, matching the state floor. Height is governed by the dimensional table at Section 175-29.

What is the Watershed Protection District and does it affect an ADU?

It is an overlay at Section 175-24 covering a substantial part of Abington. It caps impervious surface at 15% of lot area or 2,500 square feet, whichever is greater, and caps septic design flow at 110 gallons per day per 10,000 square feet of lot area. On a septic lot inside the overlay, that flow cap frequently decides whether an ADU is possible, independently of the zoning.

Does Abington require a special permit for an ADU?

A protected use ADU is allowed by right, and the state bars a town from requiring a special permit or public hearing for one. Confirm the review path that applies to your lot with the Planning Department before filing.