Harwich, MA

Harwich, MA Accessory Dwelling Unit (ADU) Rules


City Acceptance Rating: 9/10 (10 is most accepting)

What you need to know 

Harwich allows both detached and attached ADUs to be constructed with a special permit from the Zoning Board of Appeals.

Construction rules

  • Only one additional unit can be created on a single family lot.

  • The ADU can not be sold separately or owned by a separate entity.

  • Only one of the units (primary or ADU) on the property may be rented at any given time.

  • The ADU’s net floor area must be 1/2 of the net floor area of the primary home or 900 square feet, whichever is less.

  • The ADU must have two bedrooms or less.

  • At least one off-street parking space shall be provided for the accessory dwelling unit.

  • Minimum lot sizes apply as follows:

    • 15,000 SF in districts RH-1, CV, CH-1, MRL or MRL-1

    • 20,000 SF in districts RL, RM or RR District

    • 40,000 SF in a Water Resource (WR) Overlay District

  • The ADU shall be designed so the property continues to look like a single-family property.

  • The ADU exterior must match the character of the existing home with matching materials, colors, window styles and roof design.

  • An addition or detached ADU must not exceed the site coverage for the zoning district.

  • Setbacks will follow the zoning district’s rules for new construction.

See the full text here: Zoning Ordinance Article 10, Section H: Single-family dwelling with accessory apartment

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