Key Requirements
Permit Type
By Right
Permit Authority
Building Department
Local Terminology
ADU
Max Size (sq ft)
900
Max Size (% of principal)
50%
Size Rule
Whichever is smaller
Attached Allowed
Yes
Detached Allowed
Yes
Internal Allowed
Yes
Parking Spaces Required
1
Transit Exemption
Yes
Short-Term Rental
Prohibited
Owner Occupancy Required
No
Design Review Required
Yes
Historic District Review
—
Energy Code
Stretch Code
HERS Rating Required
Yes
Max HERS Index (ADU)
52
Quick Summary
- Rockport has voted to allow ADUs by right in all zoned areas, aligning with the state Affordable Homes Act.
- The key local change was eliminating the prior requirement that a lot must be large enough for two dwelling units before an ADU could be built -- critical for Rockport's many small and nonconforming lots.
- Standard state rules apply: maximum 900 sq ft or 50% of the principal dwelling, whichever is smaller.
- No owner-occupancy requirement (preempted by state law). No family-member restrictions.
- As a coastal community with historic character, environmental and design considerations may apply on a per-lot basis.
Requirements at a Glance
| Requirement | Rule |
|---|---|
| Permit type | By right |
| Max size | 900 sq ft or 50% of principal dwelling, whichever is smaller |
| Max bedrooms | Not specified in available source |
| Max bathrooms | Not specified in available source |
| Attached allowed | Yes |
| Detached allowed | Yes |
| Internal allowed | Yes |
| Parking | Max 1 space (0 within 0.5 mi of transit) |
| Short-term rental | Prohibited (minimum 30 consecutive days) |
| Owner occupancy | Not required (preempted by state law) |
| Separate entrance | Required |
| Districts | All zoned areas |
| Lot size minimum | None (previous two-dwelling-unit requirement eliminated) |
ADU Questions in Rockport
Can I build an ADU in Rockport, MA?
Yes. Accessory dwelling units are allowed by right in Rockport, MA, meaning you do not need a special permit or a zoning variance as long as the unit meets the town's dimensional rules. You still need a building permit from the Building Department. Rockport calls these "ADU."
How big can an ADU be in Rockport, MA?
Rockport limits an accessory dwelling unit to 900 square feet or 50% of the principal dwelling, whichever is smaller. State law protects ADUs up to 900 square feet on single-family lots, so a town cannot enforce a smaller cap on a protected-use ADU.
What types of ADU are allowed in Rockport, MA?
Rockport permits 3 forms of accessory dwelling unit: detached (a separate structure in the yard); attached (an addition to the house); internal (a conversion of existing space). Which one makes sense usually comes down to your lot, your septic or sewer situation, and whether you want the unit connected to the main house.
Does Rockport, MA require extra parking for an ADU?
Rockport's bylaw calls for 1 additional off-street parking space(s) for an ADU. Under state law, towns cannot require more than one space for a protected-use ADU, and no parking at all can be required within a half mile of transit.
Do I have to live on the property to rent out an ADU in Rockport, MA?
No. Rockport does not impose an owner-occupancy requirement, and state law bars towns from requiring it for protected-use ADUs. You can rent the unit without living on site.
What energy code applies to an ADU in Rockport, MA?
Rockport has adopted the Stretch Energy Code. That means a new ADU must hit a HERS rating of 52 or lower, which drives real decisions about insulation, air sealing, windows, and heating — typically an all-electric heat pump system. Budget for a HERS rater on the project from day one.
Can I use an ADU in Rockport, MA as a short-term rental?
No. Rockport prohibits using an accessory dwelling unit as a short-term rental; the minimum lease term is 30 days. The unit is intended for long-term housing. State law expressly allows towns to restrict short-term rental of ADUs, so this restriction does hold up.
Based on Rockport’s bylaw as last verified 2026-02-26. Bylaws change at annual town meetings — confirm with the Planning Board / Building Department before you build.