Service · Somerville, MA · Massachusetts
ADU design & permit drawings in Massachusetts
Since February 2025, Massachusetts allows accessory dwelling units by right in single-family zoning districts. We design and draw basement, attic, garage and detached ADUs ready for permit.
ADU types we design
- Basement ADUs with code-compliant egress
- Attic and dormer ADUs
- Garage conversions
- Detached backyard ADUs
Our ADU process
- Feasibility check: zoning, lot, existing building
- Site visit and existing-conditions measurement
- ADU layout and design
- Permit drawing set and building department follow-up
Under the Massachusetts Affordable Homes Act, a protected-use ADU can be up to 900 square feet or half the gross floor area of the main house, whichever is smaller. Each town may still apply reasonable local regulations, and every ADU needs a building permit. Read our ADU guide for Massachusetts.
FAQ
Questions
Can I build an ADU in my basement?
Often yes, if ceiling height, egress and fire separation can meet code. We verify this on site before design.