ADU Construction in Waltham MA — In-Law Suites, Garage Conversions & More
Boston Smart Plastering builds accessory dwelling units throughout Waltham, MA. Waltham is a large and diverse city 10 miles west of Boston on the Charles River — known for its mix of historic neighborhoods, active commercial corridors, and significant renovation and construction activity. Boston Smart Plastering serves Waltham homeowners and businesses across all 14 of our service trades. Whether you want a basement apartment, garage conversion, attached in-law suite, or detached backyard cottage, we manage every phase from permits to final finishes.
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ADUs are one of the smartest investments Waltham homeowners can make. Waltham's housing ranges from 19th and early 20th century multi-families near Moody Street and Central Square to mid-century single-family homes throughout residential neighborhoods to newer construction near the Route 128 tech corridor. This diversity creates consistent demand across all of Boston Smart Plastering's service categories. Under Massachusetts ADU law, most single-family properties in Middlesex County can now add an ADU by-right. Boston Smart Plastering handles the full build — design, permitting, construction, and Certificate of Occupancy. Waltham is 10 miles west of Boston along the Charles River, accessible via Route 20 and I-95/Route 128, a core part of our Middlesex County service area.
Frequently asked questions
How much does it cost to build an ADU in Waltham MA?
ADU costs in Waltham vary by type. A basement conversion typically runs $80,000–$150,000. A detached cottage can cost $180,000–$350,000+. We provide a detailed estimate after visiting your Waltham property.
Do I need a permit for an ADU in Waltham MA?
Yes — all ADU construction requires building permits. Under the 2024 Massachusetts ADU law, most Waltham properties can add an ADU by-right. We handle all permit applications for Middlesex County on your behalf.