Types of ADUs in Massachusetts

Below are the three most common ADU types, each offering unique benefits depending on your lot layout and lifestyle needs.

A detached ADU is a standalone structure separate from the main house — often built in the backyard. Think of it as a small, fully independent home on your property.

Best For:

  • Privacy for family members or renters

  • Creating a guest house or in-law suite

  • Adding long-term property value

  • Homeowners who want a completely separate living space

Benefits:

  • Maximum privacy and flexibility

  • Customizable size and layout

  • Ideal for multigenerational living

  • Often the best long-term investment

Detached ADUs are extremely popular because they function like a second small home while still staying on your existing lot.

1. Detached ADU

An attached ADU is connected to your existing home, either as an addition or as part of your current footprint (such as building off the side or back of your house).

Best For:

  • Families wanting easy access between homes

  • Lower construction costs compared to detached options

  • Properties with space on one side of the main home

Benefits:

  • More affordable than detached construction

  • Shares one wall with the main house

  • Efficient use of lot space

  • Can blend seamlessly with existing architecture

Attached ADUs are ideal when the lot has limited space or when a connected layout is preferred for caregiving.

2. Attached ADU

A garage conversion ADU transforms an existing garage (attached or detached) into a fully functioning living unit.

Best For:

  • Homeowners who want the most cost-effective ADU option

  • Properties with unused or underused garages

  • Faster build timelines

Benefits:

  • Lowest construction cost (structure already exists)

  • Minimal site work required

  • Great option for studios or one-bedroom layouts

  • Adds usable heated living space without expanding your home’s footprint

Garage conversions are one of the fastest and most budget-friendly ways to create an ADU while still meeting Massachusetts building and zoning standards.

3. Garage Conversion ADU

Which ADU Is Right for You?

Every property is different - that’s why we start with a free on-site consultation to review your lot, your goals, and your town’s regulations. Whether you're interested in a detached, attached, or garage conversion ADU, we’ll walk you through the best options, explain the permitting requirements, and help you decide what fits your long-term plan.

An Accessory Dwelling Unit (ADU) is a small, self-contained home built on the same property as an existing single-family house. It includes everything someone needs to live independently - a kitchen, bathroom, living space, and a private entrance. In Massachusetts, ADUs have become a popular way to create flexible housing for aging parents, adult children, guests, or long-term rental income.

ADUs are designed to fit naturally into your property while adding value, functionality, and additional living space without the need to buy a second home or move. They can be built in a variety of styles, depending on your property, budget, and goals.

What Is an Accessory Dwelling Unit (ADU)?

Check Your ADUs Potential