ADU CONSTRUCTION in Massachusetts — ADD SPACE, ADD VALUE
Accessory Dwelling Units are one of the smartest investments a Massachusetts homeowner can make. Boston Smart Plastering builds in-law suites, basement apartments, garage conversions, and detached backyard cottages — fully permitted, beautifully finished, and built to last.
EVERY ADU TYPE - BUILT RIGHT
An Accessory Dwelling Unit (ADU) is a self-contained residential space on the same lot as your primary home. It can be attached to the main house, built above a garage, converted from an existing basement, or constructed as a separate backyard cottage.
In Massachusetts, ADUs have exploded in popularity — and for good reason. They generate rental income, provide private space for aging parents or adult children, and add significant resale value to your property. Recent changes to Massachusetts zoning law have made ADU permitting easier than ever for most homeowners.
Boston Smart Plastering manages every phase of your ADU project — from initial design consultation and permit applications through framing, insulation, drywall, flooring, kitchenette installation, bathroom work, and final painting. One contractor, start to finish.
📋 MASSACHUSETTS ADU LAW — WHAT YOU NEED TO KNOW
As of 2024, Massachusetts law (the Affordable Homes Act) requires most municipalities to allow ADUs by-right on single-family lots — meaning no special permit or town meeting vote is required in many communities. Key points:
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ADUs up to 900 sq ft are allowed by-right in most MA communities
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Owner-occupancy requirements have been significantly relaxed
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No minimum parking requirements for ADUs near transit
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Separate metering and rental are permitted
We stay current on local zoning bylaws across Greater Boston and will advise you on exactly what's permitted on your specific property — for free, as part of your estimate.
BASEMENT ADU / APARTMENT
Convert your unfinished basement into a fully self-contained apartment with a separate entrance, kitchen, bathroom, bedroom, and living space. The most popular and cost-effective ADU option in Greater Boston.
GARAGE CONVERSION ADU
Transform an attached or detached garage into a beautiful living space. We handle insulation, framing, drywall, flooring, plumbing rough-in, electrical, and all finishes — turning dead space into rental income.
DETACHED BACKYARD COTTAGE
A fully independent structure built in your backyard — separate foundation, utilities, and entrance. The premium ADU option that maximizes privacy and rental value on larger lots.
ATTACHED IN-LAW SUITE
An addition or conversion attached to your existing home — connected internally but with a private entrance. Ideal for multigenerational families who want proximity with independence.
ABOVE-GARAGE ADU
Build above an existing detached garage to create a private apartment with natural light and separate access. Common in Boston's dense neighborhoods where lot space is limited.
INTERIOR CONVERSION ADU
Convert unused interior space — attics, large bonus rooms, or oversized primary suites — into a separate dwelling unit with minimal impact on your home's exterior.
frequently asked questions
ADU costs vary significantly by type. A basement conversion typically runs $80,000–$150,000. A garage conversion ranges from $60,000–$120,000. A detached backyard cottage can cost $180,000–$350,000+. We provide a detailed estimate after visiting your property and assessing your specific situation.
Yes — all ADU construction requires building permits, and most projects also require electrical and plumbing permits. Under the 2024 Massachusetts ADU law, many communities must now allow ADUs by-right on single-family lots, significantly streamlining the approval process. We handle all permit applications for you.
Most ADU projects take 3–6 months from permit approval to Certificate of Occupancy. The permitting process itself typically takes 4–8 weeks depending on your municipality. We'll give you a realistic schedule at your free consultation.
Yes. Massachusetts law allows ADUs to be rented as long-term rentals. Short-term rental rules (Airbnb, VRBO) vary by municipality — some Boston-area communities allow it, others restrict it. We'll help you understand the rules for your specific town.
Under the 2024 Massachusetts ADU law, owner-occupancy requirements have been significantly relaxed for many communities. The specific rules depend on your municipality. We stay current on local bylaws across Greater Boston and will advise you at your free consultation.
LET'S TALK ABOUT YOUR PROPERTY
READY TO GET STARTED?
Contact Boston Smart Plastering for a free ADU consultation. We'll visit your property, assess your options, and give you an honest picture of costs, timelines, and returns — no obligation.