Studio, about 400-450 sq ft
Open living/sleeping, kitchenette, full bath.
ADU Floor Plan Ideas for Massachusetts Homes
Short answer: in Massachusetts a by-right ADU can be up to 900 sq ft or half the main home's floor area, whichever is smaller, so most plans fall between 400 and 900 sq ft.
Sample layouts
One bedroom, about 550-650 sq ft
Separate bedroom, full kitchen, bath, small laundry.
Two bedroom, about 800-900 sq ft
Two bedrooms, one or two baths, full kitchen.
Garage conversion, about 400-500 sq ft
An ADU layout within an existing garage. Explore garage conversion ADUs.
Design tips
- Single-floor living for aging in place
- Separate entrance
- Natural light
- Storage
- Ductless heat pump
FAQ
How big can an ADU be in Massachusetts?
Up to 900 sq ft or half the main home's floor area, whichever is smaller, for a by-right ADU.
Can I use my own floor plan?
Yes. We price your plan or help develop one that fits your lot.
Is a two-bedroom ADU allowed?
Yes, as long as it stays within the size limit and meets code and septic requirements.
Related services and guides
Planning an ADU? Get a free estimate from a licensed MA contractor with $1M insurance. Call (781) 527-9445 or fill out the form.
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General information, not legal advice. Confirm rules with your town.