ADU Regulations:
Braintree
Regulations Snapshot
Rear and Side setbacks: 8 feet
Building Separation: 8 feet
Height: 18 feet / 1.5 stories
Separate utilities required: No
Stormwater management required: No
Specialized Stretch Energy Code: No
Impact Fees: Water/sewer connection fee
Building Constraints
Number of ADU’s allowed on a single family lot
Only one ADU is allowed per single-family lot, whether interior, detached, or attached
Maximum square footage of an ADU (detached or attached)
Up to 900 square feet or half the gross floor area of the primary dwelling, whichever is smaller
Maximum Height
18 feet or 1.5 stories
Maximum lot coverage
35% building coverage (includes primary dwelling, ADU, any other accessory buildings like shed or garage)
Exterior appearance requirements
The architectural character of a detached ADU shall be compatible with the primary dwelling unit and with the character of the neighborhood
Setbacks
Rear setback
8 feet
Side setback
8 feet
Front setback
Not allowed in front yard (must be behind primary dwelling)
Distance between buildings
8 feet
Parking
Parking requirement for an ADU
Each ADU requires one off-street parking space in addition to what is required for the primary dwelling. No parking space is required for an Accessory Dwelling Unit on a Lot if any portion of such Lot is located within a 0.5-mile radius of a Transit Station.
Where can the parking be located : Parking requirement for primary dwelling
Typically 2
Where can the parking be located
Not specified, only off-street
Additional Requirements
Separate utilities required
Stormwater management required
Town impact fees
Water/sewer connection fee. Also note that the town will not run separate utilities to the ADU but can be submetered from the main house
Soils report required
No, the building department will just inspect the hole prior to foundation build
Civil plans required
Yes
Short term rental allowed
No
Possible overlay districts
-If your property is in a floodplain, you may have to elevate the ADU, balance fill, or have restrictions on basement-level units. Properties in the historic district require design review and Commission approval for exterior ADU construction. If near wetlands, Conservation Commission approvals are needed for grading or structures within buffer zones.
ADUs on multifamily lots
The Braintree zoning bylaws do not allow ADUs on multifamily properties