What’s the difference between an “ADU,” “in-law suite,” and “additional dwelling unit”?

They’re all terms for the same concept — a self-contained living unit on single-family property. “ADU” (Accessory Dwelling Unit) is the formal term; “in-law suite,” “additional dwelling unit,” or “secondary unit” are common synonyms.

Can an ADU be detached or attached?

ADUs can be detached standalone units (like a cottage, guest house, or converted garage) as well as attached additions to the existing home; or built by converting existing interior space (like a basement or attic).

Does an ADU need its own kitchen, bathroom, and entrance?

Yes to qualify as an ADU it must be a fully functional, independent living unit with sleeping, cooking, bathing, and a separate entrance for privacy.

Why build an ADU / in-law suite on my property?

ADUs give you flexibility: host family members, generate rental income, provide extra privacy, or add value to your home all without buying new land.

How much does an ADU cost?

ADU's vary greatly in there size, type, and design. Unfortunately we cannot accurately provide a ball park price range for these projects.

What is the cost to get a quote for the estimate?

We perform a free discovery call and initial visit. If you would like to move forward with the design phase, there is a fee for the Architech, cost depends on project scope.

I have a septic tank, can I still build an ADU?

Yes, but we will need to get your septic systerm evaluated. The min requirment for most municipalities is to have a septic shelf plan on file which is a plan to install a new septic system.

ADU Construction & In-Law Suite Services in Maine, Massachusetts & New Hampshire

Accessory Dwelling Units, often called ADUs, in-law suites, or secondary living spaces give homeowners flexible options for family, guests, or potential rental income while staying on the same property. As an ADU builder serving homeowners in New England, we help plan, design, and construct ADUs that meet local requirements, blend with existing homes, and function well for everyday living.

What an ADU Actually Is (And How It Works on Your Property)

Bright, open-plan interior with kitchen, dining area, and living space. White walls, wooden floors, and natural light.

An ADU is a separate, self-contained living space built on the same property as an existing home. It typically includes a bedroom or sleeping area, bathroom, and small kitchen, and can be attached to the main house, built as a standalone structure, or created by converting existing space.

The right ADU depends on zoning, lot layout, utilities, privacy needs, and how the space will be used, whether for family, aging parents, downsizing, or supplemental income.

Looking for more space?

Schedule Your FREE Discovery Call

Types of ADUs We Build

There’s no one-size-fits-all ADU. We help homeowners choose the right approach for their property.

ADUs can take several forms:

Detached Backyard ADU — standalone cottage or tiny-home style builds

Attached ADU / In-Law Suite — connected to the main home with its own entrance

Garage Conversion ADU — converting existing space into a livable unit

Basement ADU — lower-level living spaces designed with proper egress and moisture control

Each ADU is designed to include independent living amenities bedroom, kitchen (or kitchenette), bathroom, and separate entrance ensuring privacy and functionality regardless of how it’s built.

Our Approach to ADU Design and Construction

ADUs are more complex than most home projects because they act like small homes on the same property. Our focus is on planning first and building second.

Architectural rendering shows a brown two-story building labeled

Feasibility + Zoning Review

Understanding setbacks, lot coverage, height restrictions, and local ADU rules.

Top-down view of a small house interior with a living area, bedroom, and kitchen. Wooden floors, a round dining table, and large window.

Design and Layout Planning

Making the space functional, private, and comfortable.

Gray electrical meter box on a house with gray siding and white trim. Gray conduit pipes below.

Utility Planning

Determining the best approach for water, electrical, sewer, and HVAC.

Cutaway diagram of a house illustrating rainwater harvesting and drainage systems. Blue and orange pipes are visible.

Structural and Site Considerations

Foundations, drainage, grading, access paths, and tie-ins.

Permitting and Inspections

Managing approvals so the project is built legally and correctly.

Budgeting and Cost Considerations for ADU Projects

One of the most important conversations in any ADU project is understanding realistic budget ranges before design moves too far. ADUs function like small homes, which means they include many of the same components foundation, framing, roofing, electrical, plumbing, and finishes all within a smaller footprint.

Calculator, notepad, and pen on a table covered with US dollar bills.

Costs are influenced by size, design complexity, utilities, and site conditions

Detached units typically cost more than interior conversions because they require additional foundations and utilities

Conversions may appear simpler, but upgrades for code compliance and safety can affect pricing

Planning the budget early helps guide design decisions instead of forcing changes later

Our role is to walk homeowners through budget expectations up front, so the design aligns with what makes sense financially before any major commitments are made.

Frequently Asked Questions About ADU Construction & In-Law Suites

What’s the difference between an “ADU,” “in-law suite,” and “additional dwelling unit”?
They’re all terms for the same concept — a self-contained living unit on single-family property. “ADU” (Accessory Dwelling Unit) is the formal term; “in-law suite,” “additional dwelling unit,” or “secondary unit” are common synonyms.
Can an ADU be detached or attached?
ADUs can be detached standalone units (like a cottage, guest house, or converted garage) as well as attached additions to the existing home; or built by converting existing interior space (like a basement or attic).
Does an ADU need its own kitchen, bathroom, and entrance?
Yes to qualify as an ADU it must be a fully functional, independent living unit with sleeping, cooking, bathing, and a separate entrance for privacy.
Why build an ADU / in-law suite on my property?
ADUs give you flexibility: host family members, generate rental income, provide extra privacy, or add value to your home all without buying new land.
How much does an ADU cost?
ADU's vary greatly in there size, type, and design. Unfortunately we cannot accurately provide a ball park price range for these projects.
What is the cost to get a quote for the estimate?
We perform a free discovery call and initial visit. If you would like to move forward with the design phase, there is a fee for the Architech, cost depends on project scope.
I have a septic tank, can I still build an ADU?
Yes, but we will need to get your septic systerm evaluated. The min requirment for most municipalities is to have a septic shelf plan on file which is a plan to install a new septic system.

Is an ADU the Right Move for Your Property?

Whether you’re exploring an in-law suite, guest space, or a small detached unit, we’re happy to talk through feasibility, costs, and next steps so you can make an informed decision before moving forward.

Schedule Your Free Discovery Call Today