T&J Builders specializes in custom ADUs in Dover NH, Portsmouth NH, NH Seacoast, Lakes Region & Southern Maine. Services include garage conversions, in-law suites & detached cottages for rental income, multigenerational living & added property value.
read more
Réal Hazen Construction builds ADUs in Vermont and New Hampshire. Attached ADUs cost $100K–$250K; detached $200K–$350K+. Services include drafting, permitting, budgeting, and full construction, with builds completed in 2–4 months.
read more
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 warranty.
read more
Summit 48 Construction builds luxury ADUs in NH's Lakes Region, including guest houses, in-law suites & carriage homes. Custom finishes, zoning knowledge & full project management from design to completion.
read more
SRH Homes builds custom ADUs, including 500 SF 1-bed and 800 SF 2-bed units. Options include high-end finishes and mini-split HVAC. Financing via HELOC or cash-out refinance. Ideal for rental units, granny flats, or in-law suites.
read more
Post Woodworking builds custom Accessory Dwelling Units (ADUs), including detached ADUs and in-law suites. They offer flexible involvement, from full construction management to building only, ensuring seamless integration with your existing home.
read more
Allan Tran's Exterior Finish Work (AJT Properties) specializes in residential exterior services including deck construction, porch railing installation, storage structures, and CertainTeed siding. Known for reliable communication, on-budget delivery, and durable craftsmanship.
read more
Meetinghouse Builders offers custom ADU design & construction in Hollis, NH. Services include detached builds, garage conversions, basement ADUs & home additions. Features 3D renderings, style guides & full construction documents.
read more
Oxland Builders is a design/build remodeling company in Portsmouth, NH, serving the Seacoast region since 2003. Services include kitchen & bathroom remodeling, home additions, ADUs, in-law suites, and whole-home renovations across Rockingham County and Southern Maine.
read more
Attached vs. detached ADUs in New England: Foremost Builders explains key differences. Attached ADUs cost less; detached offer more privacy and rental potential. Serving NH's Dartmouth-Lake Sunapee region since 1997.
read moreNew Hampshire is known for its strong tradition of local governance and individual property rights, making it a distinctive state for accessory dwelling unit (ADU) development. In 2017, New Hampshire passed RSA 674:71-73, a landmark state law that requires municipalities to allow ADUs as a matter of right in single-family residential zones. This legislation was a significant step forward, ensuring that homeowners across the state have the legal foundation to build ADUs on their properties. However, local municipalities still retain the authority to regulate certain aspects of ADU construction, which means experienced ADU contractors in New Hampshire must be well-versed in both state law and local zoning ordinances.
While state law provides a baseline, towns and cities such as Manchester, Concord, Nashua, and Portsmouth each have their own specific requirements that ADU contractors must navigate. These can include restrictions on the size of the ADU relative to the primary dwelling, owner-occupancy requirements, setback rules, and parking regulations. In many New Hampshire municipalities, an ADU cannot exceed 750 square feet or 30% of the existing home's floor area, whichever is greater. Contractors must also ensure compliance with the New Hampshire State Building Code, which is based on the International Residential Code (IRC), along with local amendments that may apply.
Professional ADU contractors in New Hampshire offer a comprehensive range of services tailored to the state's specific climate and regulatory environment. Given New Hampshire's cold winters and significant snowfall, contractors must prioritize proper insulation, energy-efficient windows, and robust heating systems. Common ADU types built in the state include:
Working with a knowledgeable ADU contractor in New Hampshire is essential for successfully navigating the permitting process. Contractors typically assist homeowners with site assessments, architectural drawings, permit applications, and inspections. Because New Hampshire's municipalities handle permitting independently, timelines can vary significantly from town to town. Hiring a contractor with local experience can help streamline approvals and avoid costly delays.
New Hampshire's tight housing market and growing demand for affordable rental units make ADUs an increasingly attractive investment. Homeowners can generate rental income, house aging family members, or increase overall property value. With the state's supportive legal framework under RSA 674:71-73 and a growing network of skilled ADU contractors, now is an excellent time for New Hampshire residents to explore adding an accessory dwelling unit to their property.