Printable checklist
ADU Feasibility: The Questions Worth Investigating First
Property questions you can start answering today
The lot
- Find your plot plan or survey, where are the property lines and existing structures?
- Note roughly how much yard sits beyond your house on each side, is there obvious room for a detached unit, or is conversion the realistic path?
- Is the property on town sewer or a septic system? (Your deed file, water bill, or board of health records will say.)
- If septic: locate any records of the system's design, age, and bedroom capacity.
- Any wetlands, streams, or steep slopes near where a unit might go?
- How would construction equipment reach the build area, and what would it cross to get there?
Structures you might convert
- Garage: measure ceiling height, look at the slab (cracks, slope, dampness), and note what the garage would stop storing.
- Basement: measure floor-to-joist height, note any water history through a full year of seasons, and identify where a separate entrance could go.
- Attic or wing of the house: is there a sensible separate-entrance option?
- For any conversion: where are the furnace, water heater, and electrical panel, and would they share space with the unit?
Household questions that shape the design
Who and how
- Who will live in the unit first, and honestly, who might live there in ten years?
- If it's for a parent: what does aging-friendly mean for them, zero-step entry, one-floor living, bathroom safety?
- How much privacy separation does your household actually want, separate entrance orientation, sound isolation, shared yard or divided?
- Laundry in the unit, shared, or both?
- Parking: where would one more car realistically go?
Questions for your town
Ask the building department
- Does the town have an updated ADU bylaw since the 2025 state law, and what does it require today?
- What dimensional standards (setbacks, height, coverage) apply to my district?
- Does the town use site plan review for ADUs?
- Any short-term rental restrictions on ADUs, if that ever matters to you?
- For septic properties: does the board of health have my system's records, and what would an added unit trigger?
Documents and measurements to gather
The feasibility folder
- Plot plan / survey
- Septic records (if applicable)
- Rough floor plan or sketch of spaces you'd convert, with ceiling heights
- Photos: the candidate space or yard area, electrical panel, mechanicals, any water evidence
- Your notes from the building-department conversation
- A one-paragraph statement of what the ADU is for
Worked through the list?
Bring us your feasibility folder, or just your questions. A real person will review what you've got and tell you what the realistic next step looks like. You can also try our quick ADU questionnaire first.
Tell us what you’re considering. A real person will review your request, and we will not sell or distribute your project information.