ADU Regulations:
Milton
Regulations Snapshot
Rear and Side setbacks: 10 feet
Building Separation: 12 feet
Height: one story
Separate utilities required: No
Stormwater management: No
Specialized Stretch Energy Code: Yes
Impact Fees: Water/sewer connection
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
If you use the accessory structure setbacks of 10 ft the ADU can only be one story/15 ft. If you want to build a 2 story ADU you must abide by the setbacks of the primary structure
Exterior appearance requirements
For detached or attached ADUs, the design,including roof pitch, siding materials, windows, and overall massing, must align with the architectural style of the principal dwelling and surrounding neighborhood
Setbacks
Rear setback
10 ft for accessory structures *read note regarding height
Side setback
10 ft for accessory structures *read note regarding height
Front setback
40 ft from street unless flush with or behind the primary dwelling Distance between buildings
Distance between buildings
12 ft from primary dwelling
Parking
Parking requirement for an ADU
Every ADU must include at least one additional off-street parking space on the same property.
This can be a driveway or paved/gravel area and must be screened from public view if it’s not in a garage. It must be clearly designated and not replace any required parking for the main residence. If your property is within 0.5 miles of a transit station the requirement is waived.
Where can the parking be located : Parking requirement for primary dwelling
Residential districts AA, A, and B, each detached single-family home must provide at least two off-street parking spaces, located on the same lot, or on adjacent lots under common ownership. In Residence C, one off-street parking space is required per single-family home
Additional Requirements
Separate utilities required
Stormwater management required
Get assessment on stormwater based on paved area in driveway, if put in additional parking for ADU would be reflected in that. DPW does assessment. Just need to pay fee.
Town impact fees
No impact fees
Soils report required
Generally do not require. The building inspector will inspect the hole for the foundation prior to construction
Civil plans required
Yes
Short term rental allowed
No
Possible overlay districts
If you’re planning an ADU or renovation, you’re not restricted by a historic zoning overlay. However, if your property is within a designated historic district or contains a historically significant building, and you plan demolition or material alteration, your proposal may require review under Chapter 163 rules.
There is also a wetland overlay that can be viewed through the Milton GIS map. If any part of your lot lies within the wetland buffer zones, perturbation here triggers Conservation Commission review.
ADUs on multifamily lots
Multifamily properties are excluded entirely from ADU eligibility per Milton’s zoning amendment article 38 and existing bylaws