Accessory Dwelling Unit Boston: Building Smarter, Living Better An Accessory Dwelling Unit Boston (ADU) is a small, self - contained living unit built on the same lot as a main home — either within the existing structure or as an external unit. With growing demand for flexible housing, an Accessory Dwelling Unit Boston offers homeowners the opportunity to increase living space, generate income, or accommodate changing family needs. What Boston’s Rules Say Massachusetts recently passed the Affordable Homes Act (Chapter 150 of the Acts of 2024) which allows ADUs under 900 square feet to be built by - right in single - family zoning districts. This means fewer obstacles for homeowners eyeing an Accessory Dwelling Unit Boston. Permits are less burdensome, so long as local building code and safety requirements are met. Financial Tools & Support Boston provides financial assistance programs to help make building an Accessory Dwelling Unit Boston more affordable. Examples include the Boston Home Center’s ADU Financial Assistance Program, which offers both grants (for design and permitting) and deferred, zero - interest loans (up to about $50,000) for eligible homeowners of 1 - 3 unit buildings. Income eligibility and home - occupancy requirements apply. Benefits of an Accessory Dwelling Unit Boston Rental Income & Fina ncial Flexibility : ADUs offer a source of supplemental income, helping with mortgage payments or living costs. Multigenerational Living : ADUs support families, aging parents, or adult children seeking semi - independent living close by. Increase in Property Value : Homes with legal, well - constructed ADUs tend to be more valuable and attractive to buyers. Efficient Use of Land : Boston’s limited space makes ADUs an efficient way to add housing without sprawling outward. Considerations Before You Build Planning a n Accessory Dwelling Unit Boston involves knowing local code requirements: size limits (generally ≤ 900 sq ft or 50 % of the main home, whichever is smaller), ceiling height, egress windows, saf ety concerns, and adherence to building and zoning ordinances. Also check local permitting times and whether your design will require special approvals. How United ADUs Helps At United ADUs , we help homeowners with every step of bringing an Accessory Dwel ling Unit Boston to life: Feasibility and design tailored to Boston’s zoning laws. Guidance on applying for grants and loans offered by the city. Permit submission, inspections, and code compliance. Construction management with quality finishes. If you’re considering an Accessory Dwelling Unit Boston , we offer expert support so your ADU project is legal, functional, and adds value.