[Added 1-9-2025 STM by Art. 15]
The intent of permitting accessory dwelling units is to: 1. Provide homeowners with a means of obtaining rental income, companionship, security, and services, thereby enabling them to stay more comfortably in homes and neighborhoods they might otherwise be forced to leave; 2. Add moderately priced rental units to the housing stock to meet the needs of smaller households and make housing units available to moderate-income households who might otherwise have difficulty finding housing; 3. Develop housing units in single-family neighborhoods that are appropriate for households at a variety of stages in their life cycle; 4. Provide housing units for persons with disabilities; 5. Protect stability, property values, and the residential character of a neighborhood.
A. Use and dimensional regulations:
(1) Attached accessory dwelling units (with or without enlarging the dwelling) are allowed as-of-right with a building permit from the Building Inspector (see §
230-7.1).
(2) Detached accessory dwelling units created within an existing accessory structure or as an additional accessory structure require administrative site plan approval (see §
230-5.3).
(3) The Building Inspector may issue a building permit authorizing the installation and use of an accessory dwelling unit within an existing or new dwelling, and administrative site plan approval may be issued authorizing the installation and use of an accessory dwelling unit in a detached structure on a lot only when the following conditions are met:
(a) The unit will be a complete, separate housekeeping unit containing both kitchen and bath.
(b) The accessory dwelling unit should be designed so that the appearance of the structure remains that of a dwelling, subject further to the following conditions and requirements:
[1] All stairways to the second and third stories shall be enclosed within the exterior walls of the dwelling, with the exception of an open staircase which may be permitted at the rear of the building when such an open staircase does not detract from the single-family character of the building.
[2] Any new separate outside entrance serving an accessory dwelling unit shall be located on the side or in the rear of the building unless it is a detached accessory structure.
(c) The maximum gross floor area of the accessory apartment shall not exceed 1/2 the gross floor area of the principal dwelling or 900 square feet, whichever is smaller.
(d) Attached and detached Accessory Dwelling Units must meet the dimensional regulations of the underlying residential district as found in Schedule 4.2A.
| R1 | R2 | R3 | RD |
|---|
Front setback | 40' | 30' | 30' | 30' |
Side setback | 25' | 15' | 15' | 15' |
Rear setback | 40' | 30' | 30' | 30' |
Maximum height | No higher than the principal structure or 35' |
(e) Lots with accessory dwelling units must meet the following open space requirement (attached and detached ADUs), which differs from Schedule 4.2A:
| R1 | R2 | R3 | RD |
|---|
Total Open Space for Lot (Attached & Detached ADUs) | 40% | 40% | 40% | 40% |
(f) Accessory dwelling units within 20 feet of side or rear property lines shall provide the strongest possible visual barrier with landscaping and/or fencing. To the greatest feasible extent, existing healthy, mature vegetation shall be retained in place or transplanted and reused on site.
(g) Any new site lighting for the accessory dwelling unit shall be fully shielded and downward facing so as not to provide glare or light trespass over property lines.
(h) Once an accessory dwelling unit has been added to a single-family residence or lot, the accessory dwelling unit shall never be enlarged beyond the square footage allowed by this bylaw.
(i) The construction of any accessory dwelling unit must comply with the separation requirements and other elements of the State Building Code for structures; Title V, Minimum Standards for Human Habitation, and other provisions of the State Sanitary Code; and other local environmental or engineering bylaws/ordinances and regulations.
[1] To encourage the development of accessible housing units for persons with limited mobility, the Planning Board may allow reasonable deviation from the stated conditions where necessary to install features that facilitate access and mobility for disabled persons.
[2] Prior to the issuance of a permit, a floor plan must be submitted showing the proposed interior and exterior changes to the building.
[3] Existing accessory apartments or in-law units: all previously approved accessory apartment special permits (under §
230-3.9) and in-law apartments are considered pre-existing. Conversion is permissible if this provision can be met.
[4] Pre-existing nonconforming lots and structures: all lots or dwellings that are noncompliant shall follow the provisions of §
230-3.10.
[5] For more than one accessory dwelling unit in any district that allows single family dwelling units, the Planning Board may issue a special permit from under §
230-5.5.
B. Parking.
(1) One space should be available for use by the occupant(s) of the accessory dwelling unit; No additional parking spaces shall be required for an accessory dwelling unit located within a 0.5-mile radius of the commuter rail station.
(2) Each parking space and the driveway leading thereto shall be paved or shall have an all-weather gravel surface. No motor vehicles shall be regularly parked on the premises other than in such a parking space.
(3) All parking spaces shall be either:
(a) Outdoor parking spaces located in a side or rear yard; or
(4) There shall be no more than four outdoor parking spaces on the lot with one curb cut.
(5) No parking space shall be located within the boundary of a street right-of-way.
(6) Where there are more than two outdoor parking spaces added, they shall be screened with evergreen or dense deciduous plantings, walls, fence, or a combination thereof. Screening shall be sufficient to minimize the visual impact on abutters and to maintain the single-family appearance of the neighborhood.
C. Administration and enforcement.
(1) It shall be the duty of the Building Inspector to administer and enforce the provisions of this Bylaw (see §
230-7.1).
(2) No building shall be constructed or changed in use or configuration until the Building Inspector issues a permit. No permit shall be issued until a sewage disposal works permit, when applicable, has first been obtained from the Board of Health and the proposed building and location thereof conform with the town's laws and bylaws. Any new building or structure shall conform to all adopted state and town laws, bylaws, codes, and regulations. No building shall be occupied until a certificate of occupancy has been issued by the Building Inspector where required.
(3) The Building Inspector shall refuse to issue any permit which would result in a violation of any provision of this chapter or in a violation of the conditions or terms of any special permit or variance granted by the Planning Board or the Board of Appeals.
(4) The Building Inspector shall issue a cease and desist order on any work in progress or on the use of any premises, either of which are in violation of the provisions of this section.
D. Short-term rentals.
(1) Accessory dwelling units shall not be rented for periods of less than 30 days at a time.