Accessory Dwelling Units (ADUs) in the Boston Metro Area
Northwoods Builders is a leading ADU design‑build firm serving the Boston Metro Area. We specialize in planning, designing, and constructing high‑quality Accessory Dwelling Units (ADUs) that expand your living space, support multigenerational living, and increase long‑term property value. Whether you’re considering an in‑law suite, backyard cottage, rental apartment, or guest house, our team creates secondary dwellings that feel intentional, private, and architecturally cohesive with your home.
An Accessory Dwelling Unit (ADU) is a self‑contained residential structure located on the same lot as a primary home, complete with its own kitchen, bathroom, living area, and private entrance. With the 2024 Massachusetts Affordable Homes Act now in effect, many homeowners can now build certain ADUs by right in residential districts—making the process more accessible than ever.
We provide ADU services throughout Acton, Arlington, Concord, Cambridge, Lexington, Harvard, and surrounding Greater Boston communities.
Quick Answers About Building an ADU in Massachusetts
Do I need a permit to build an ADU?
Yes. Even when an ADU is allowed by right, homeowners must obtain building permits and comply with local zoning and building codes.
How large can an ADU be in Massachusetts?
Many communities allow ADUs up to 900 square feet or up to 50% of the primary home’s size, depending on local regulations.
Can I build an ADU on any residential lot?
Most single‑family lots qualify, but setbacks, lot coverage, septic capacity, and other site conditions must be evaluated.
Can I build an ADU if I have a septic system?
Often yes. Your septic system must be assessed for capacity, and many towns require a septic reserve area (or “shelf plan”) for future expansion if needed.
Can an ADU be used as a rental unit?
Long‑term rentals are commonly permitted. Short‑term rental rules vary by municipality and should be reviewed during planning.
Why More Boston Area Homeowners Are Building ADUs
ADUs have become one of the most in‑demand home improvements in Massachusetts. Homeowners are choosing ADUs to:
- Create independent living space for aging parents or adult children
- Support multigenerational living while maintaining privacy
- Add a rental unit for long‑term income
- Increase overall property value
- Provide flexible space for guests, caregivers, or remote work
- Adapt their home without the cost and disruption of moving
With rising housing demand and updated state regulations, ADUs offer both lifestyle benefits and strong financial returns.
Types of ADUs We Design and Build
Attached ADUs
Additions that extend your home while providing a fully independent living space. Ideal for in‑law suites or private family apartments.
Detached ADUs
Standalone structures such as backyard cottages, carriage houses, or guest homes. These offer maximum privacy and rental potential.
Internal ADUs
Conversions within your existing home footprint, including basement apartments, attic conversions, and over‑garage living spaces.
Every ADU we build is designed to meet Massachusetts building codes, local zoning requirements, and modern energy‑efficiency standards.
Our Massachusetts ADU Design Build Process
Building an ADU in Massachusetts requires careful planning, zoning knowledge, and seamless coordination. As a full‑service design‑build firm, Northwoods Builders manages the entire process:
- Feasibility studies and zoning review
- Architectural design and space planning
- Structural engineering and utility coordination
- Permitting and regulatory approvals
- Construction, project management, and final finishes
By keeping design and construction under one roof, we streamline communication, reduce delays, and deliver a cohesive ADU that feels like it has always belonged on your property.
Project timelines and budgets depend on:
- ADU type (attached, detached, or internal conversion)
- Utility upgrades and infrastructure needs
- Foundation and site conditions
- Structural modifications
- Interior finish selections
We walk you through these considerations early so you can make informed decisions with clarity and confidence.
Start Planning Your ADU in the Boston Metro Area
If you’re considering building an ADU in Acton, Concord, Lexington, Arlington, Cambridge, or anywhere in the Greater Boston region, Northwoods Builders can help you evaluate feasibility, navigate permitting, and design a space that supports your long‑term goals.
Schedule a consultation to begin planning your ADU with our Massachusetts design‑build team.