Whitman · Plymouth County

Can you build an ADU in Whitman?

Whitman's Section 240-6.6 is the longest ADU bylaw on this list and the most particular. It grandfathers every accessory apartment the town ever special permitted, then adds four conditions the state floor does not, one of which closes off the cheapest way to build one.

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 Whitman adds on top

Rule	In Whitman
Where allowed	By right on a lot with a principal single-family dwelling, in Single Residence A-1, Single Residence A-2 and General Residence
Maximum size	Half the principal dwelling's gross floor area or 900 sq ft, whichever is smaller
Minimum size	400 sq ft of gross floor area
Review	Site Plan Approval by the Board of Appeals under Section 240-7.2, unless the unit sits wholly within the existing principal dwelling
Owner occupancy	Not required, and no familial relationship required either
In an accessory structure	Only if that structure already meets the dimensional and density rules for a principal dwelling in the district, under Section 240-6.5
Also for outbuildings	Must be on a foundation and connected to utilities. A trailer cannot be an ADU. A modular unit meeting 760 CMR 71.02 can
Parking	Two off-street spaces for the house plus one for the ADU, unless the lot is within half a mile of a transit station. The extra space uses the existing driveway
Appearance	Inside the house or in an addition, the structure must still read as a single-family dwelling, with any new stairway to an upper storey enclosed within the exterior walls
Condominium	Barred. An ADU cannot go on a lot already submitted to MGL c.183A, and a lot with an ADU can never be submitted to it afterwards
Subdivision	A lot with the house and a detached ADU cannot later be split unless both resulting lots meet Section 240-6.5 on their own
Short-term rental	Prohibited, per MGL c.64G Section 1
Existing accessory apartments	Anything previously special permitted becomes an ADU by right, and the old owner-occupancy and familial-relationship conditions fall away

Subsection G is the one that costs money. An ADU may only go in an accessory structure if that structure already satisfies the dimensional and density rules for a principal dwelling, which an ordinary garage set near a lot line does not. Braintree explicitly allows converting a nonconforming outbuilding; Whitman closes that door, so the cheap path is a conversion inside the house, and that is also the only path that avoids Board of Appeals site plan approval. Subsection K deserves a second look from anyone thinking about an exit: once a lot carries an ADU it can never be submitted to the condominium statute, which removes one way of separating and selling the units later. Subsection I is more generous than it first reads, though. Putting an ADU wholly inside a dimensionally nonconforming house, or on a nonconforming lot, is by right, and where an addition does need Board of Appeals review the board is expressly barred from taking the ADU use itself into account.

Questions people ask

Is there a minimum size for an ADU in Whitman?

Yes. An accessory dwelling unit must have a gross floor area of at least 400 square feet, and no more than half the principal dwelling's gross floor area or 900 square feet, whichever is smaller.

Can I convert my garage into an ADU in Whitman?

Only if the garage already satisfies the dimensional and density regulations that apply to a principal dwelling in that district, under Section 240-6.5. Most detached garages sit closer to a lot line than a house may, so in practice this rules the conversion out. It must also be on a foundation and connected to utilities.

Does Whitman require a hearing for an ADU?

An ADU located wholly within the existing principal dwelling does not require site plan approval. Anything else requires Site Plan Approval from the Board of Appeals under Section 240-7.2.

I already have a permitted accessory apartment in Whitman. What happens to it?

It is now treated as an Accessory Dwelling Unit and its continued use is allowed by right. The owner-occupancy and familial-relationship conditions imposed under the old version of the bylaw no longer apply to it.

Can I condo the units in Whitman later?

No. An ADU cannot be created on a lot already submitted to MGL Chapter 183A, and a lot containing an ADU cannot be submitted to it afterwards. A lot with a detached ADU also cannot be subdivided unless both resulting lots independently satisfy Section 240-6.5.