Boston's Premier
ADU Builder

In Boston, ADUs are typically limited to a maximum of 900 square feet or 50% of the primary dwelling's square footage, whichever is smaller. The minimum size is generally 190 square feet, as required by building codes for habitable spaces. These restrictions ensure that the ADU remains accessory to the main dwelling while still providing adequate living space. Height restrictions vary by zoning district and are measured differently for attached versus detached ADUs.

Building an ADU in Boston typically requires several permits: a Building Permit from the Inspectional Services Department (ISD), a Zoning Relief permit if your project requires variances, electrical, plumbing, and mechanical permits for respective systems, and possibly a Historic District Commission approval if your property is in a designated historic district. Some projects may also require Conservation Commission approval if near wetlands. Our team handles all permit applications as part of our comprehensive service.

Setback requirements for ADUs in Boston vary by zoning district but typically include: front yard setbacks of 10-20 feet, side yard setbacks of 5-15 feet, and rear yard setbacks of 20-30 feet. Corner lots have special considerations. Attached ADUs follow the same setbacks as the main house, while detached ADUs often have different requirements. Existing non-conforming structures (like garages) being converted may be eligible for special provisions if not expanding the footprint.

Yes, you can build ADUs in Boston's historic districts, but with additional oversight. Projects require Historic District Commission (HDC) approval focusing on exterior appearance, materials, and compatibility with neighborhood character. The review process adds 1-3 months to the timeline. ADUs that aren't visible from public ways have higher approval rates. We have extensive experience working with Boston's historic commissions and can guide your project through this process.

Yes, Boston requires that the property owner live in either the main dwelling or the ADU. This owner-occupancy requirement is designed to ensure that ADUs serve the community by housing residents rather than becoming purely investment properties. The owner can choose which unit to occupy and can change between units over time. This requirement must be maintained for the life of the ADU permit.

The permitting timeline for ADUs in Boston typically ranges from 3-8 months, depending on project complexity and whether zoning relief is required. Simple projects that conform to all zoning requirements may take 3-4 months, while projects requiring variances or special permits can take 6-8 months. Historic district reviews add additional time. We work proactively with city departments to minimize delays and keep your project moving forward.

We offer comprehensive ADU design options including detached units (standalone structures), attached additions, basement conversions, garage conversions, and attic conversions. Each type can be customized with studio, one-bedroom, or two-bedroom layouts. Our designs prioritize functionality, natural light, and compliance with Boston building codes while complementing your existing home's architecture.

Our design team specializes in creating ADUs that complement Boston's diverse architectural styles, from Victorian and Colonial to modern designs. We analyze your existing home's materials, proportions, rooflines, and design elements to create a cohesive appearance. We also consider neighborhood character guidelines and historic district requirements to ensure your ADU enhances rather than detracts from the area's aesthetic.

Absolutely! We work closely with you to design layouts that meet your specific needs and maximize functionality within Boston's size constraints. Whether you're optimizing for rental income, creating accessible space for aging family members, or establishing a home office with living quarters, we customize every aspect of the interior design including kitchen layouts, bathroom configurations, storage solutions, and living spaces.

We can incorporate various accessibility features into your ADU design, including step-free entrances, wider doorways, accessible bathroom layouts, and universal design principles. While ADUs aren't required to meet full ADA compliance, thoughtful accessibility design can make your ADU suitable for aging in place or accommodating family members with mobility needs. These features also increase the rental market appeal of your unit.

Yes, our design process includes detailed 3D renderings and virtual walkthroughs so you can visualize your ADU before construction begins. These tools help you understand spatial relationships, test different layout options, select finishes, and make informed decisions about your project. We also use these renderings for permitting submissions and neighborhood presentations when required.

We incorporate numerous sustainable design features including high-performance insulation, energy-efficient windows and doors, LED lighting systems, ENERGY STAR appliances, low-flow plumbing fixtures, and sustainable building materials. We can also design for solar panel installation, electric vehicle charging, and smart home systems. These features reduce environmental impact, lower utility costs, and increase your ADU's long-term value.

Construction timelines vary based on ADU type and complexity. Basement and garage conversions typically take 2-4 months, attached ADUs take 3-5 months, and detached new construction takes 4-7 months. These timelines assume permits are in place and don't include design and permitting phases. Weather, material availability, and change orders can affect schedules. We provide detailed timeline estimates during project planning.

We minimize disruption through careful planning and clear communication. For detached ADUs, most work occurs away from your main living areas. For conversions and additions, we coordinate work schedules around your routine, provide advance notice of noisy activities, and arrange temporary accommodations for utilities when needed. Our project managers maintain daily communication and help you prepare for each phase of construction.

ADUs require complete electrical, plumbing, and HVAC systems. Depending on your setup, utilities can be extended from your main house or installed as separate connections. We coordinate all utility work with city departments and utility companies, including meter installations if separate billing is desired. Internet, cable, and security systems can also be integrated during construction.

Yes, we manage all required inspections throughout construction, including foundation, framing, electrical, plumbing, insulation, and final occupancy inspections. Our team coordinates with Boston building inspectors, addresses any issues that arise, and ensures all work meets code requirements. We don't consider the project complete until you receive your certificate of occupancy.

We provide comprehensive warranties including a one-year workmanship warranty on all construction, manufacturer warranties on appliances and fixtures, and extended warranties on major systems like HVAC and roofing. We also offer ongoing maintenance support and emergency service for the first year. Our commitment to quality means we stand behind our work long after project completion.

Our quality control process includes regular site inspections by project managers, photo documentation of work progress, third-party inspections at key milestones, and final walkthroughs with homeowners before completion. We use detailed checklists, maintain clean and organized job sites, and address any concerns immediately. Our reputation depends on delivering exceptional quality on every project.

ADU costs in Boston vary significantly based on type, size, and finishes. Basement conversions typically range from $80,000-$150,000, garage conversions $100,000-$200,000, attached ADUs $150,000-$250,000, and detached new construction $200,000-$400,000. These estimates include design, permits, and construction but may vary based on site conditions, material selections, and project complexity.

Common financing options include home equity loans, home equity lines of credit (HELOC), cash-out refinancing, construction loans, and personal loans. Some lenders offer specialized ADU financing programs with favorable terms. The potential rental income from your ADU can help qualify you for larger loan amounts. We work with several preferred lenders who understand ADU projects and can provide competitive rates.

Boston ADUs typically generate $1,500-$3,500 monthly rental income depending on size, location, and amenities. With proper financing, many ADUs achieve positive cash flow immediately and full cost recovery within 8-15 years. Properties near universities, downtown, or public transit command higher rents. The exact payback period depends on your construction costs, financing terms, and local rental market conditions.

ADUs can provide several tax benefits including depreciation deductions for the rental portion of your property, deductions for maintenance and repairs, interest deductions on ADU-related loans, and potential home office deductions if used for business. You may also benefit from capital gains advantages when selling. Consult with a tax professional to understand how an ADU fits into your specific financial situation.

Yes, we provide fixed-price contracts for most ADU projects, protecting you from cost overruns and giving you budget certainty. Our detailed estimates include all anticipated costs for design, permits, construction, and standard finishes. We only recommend change orders for improvements you request during construction. This approach eliminates surprise costs and helps you plan your financing accurately.

Well-designed ADUs typically increase property values by $75,000-$200,000 in Boston, often recovering 70-90% of construction costs in added value. The exact increase depends on neighborhood characteristics, ADU quality, local market conditions, and comparable sales. Beyond immediate value, ADUs provide ongoing rental income and increased housing flexibility, making properties more attractive to future buyers.