Detached ADU near Portsmouth, NH

River City Construction is a Boston-based ADU contractor specializing in home additions, garage conversions, in-law suites & detached backyard cottages. They manage design, permitting & full construction under one roof.

Honorato Company offers a structured construction process in Boston, covering ADUs, garage conversions & renovations. From consultation to final walkthrough, they ensure transparency, permitting, design, and clear communication throughout.

Top Notch Contracting is a Massachusetts ADU builder specializing in detached backyard cottages, garage conversions, in-law suites, and multigenerational spaces. They manage permitting, construction, and completion across Boston and MA.

Planning an ADU in Massachusetts? Costs range from $250–$500+ per sq ft. State law now allows ADUs by right on single-family lots. Learn about permits, the Stretch Energy Code, and working with a qualified ADU contractor in Greater Boston.

Turkel Design offers custom-designed accessory dwelling units (ADUs) using a prefab process. Highlights include expert cabinetry, smart storage, and high-quality finishes, ensuring ADUs feel purposeful and cohesive with the main residence.

ADUs are now legal statewide in Massachusetts. Atlantic Property Development builds custom Accessory Dwelling Units on the North Shore, offering design, permitting, and construction services for detached, attached, and garage conversion ADUs.

BlackDog Builders offers full-service ADU design/build solutions, handling design, permitting, and construction under one roof. Specializing in detached ADUs, backyard cottages, in-law suites, and granny flats, they back projects with a 3-year war... read more

Alcantara Construction is an experienced ADU contractor specializing in detached ADUs, garage conversions, JADUs, in-law suites, and granny flats. They guide homeowners through planning, permitting, and building accessory dwelling units efficientl... read more

Trust Contractors designs and builds ADUs, including detached units, garage conversions, basement ADUs, and in-law suites. Services cover zoning, permits, and construction, helping homeowners add rental income, family housing, or flexible living s... read more

Canbury Homes is a Maine-based modular ADU builder offering diverse floor plans like Columbia II, Clinton, Cameron, and more. They guide homeowners through Maine's ADU regulations, providing customizable, affordable accessory dwelling units.