Backyard Building Feasibility Checklist

1. Your lot

• Lot width and depth, from the survey or the assessor's card. Note whether it is a corner lot or has alley access.
• Lot area in square feet, and the footprint of everything already on it (house, decks, sheds, driveway if your town counts it) for lot coverage.
• Where the main house sits: distance from each lot line, so you know how much rear and side yard is left.
• Slope across the spot you have in mind: level, mild, or steep? A level pad is simplest; steep lots need a licensed review.
• Easements, rights of way, septic field and well locations, wetlands or watercourses, big trees you want to keep.
• Soil: any known fill, wet ground, ledge near the surface, or clay? Unknown is a fair answer; it is flagged, not guessed.

2. Questions for your zoning office

• Is a detached garage, workshop or ADU allowed on my lot in my zoning district, and is it by right, by special permit, or not at all?
• Maximum size for an accessory building or ADU (square feet, or a percentage of the main house), and maximum height to the ridge.
• Front, side and rear setbacks for accessory buildings and for ADUs (they are often different), and the required distance from the main house.
• Maximum lot coverage, and whether driveways and patios count.
• For an ADU: owner-occupancy requirement, parking, minimum lot size, rental rules, any design standards such as matching the main house.
• Is a zoning permit or ADU registration needed before the building permit? Is a certified plot plan required to verify setbacks?
• Ask your building department whether it wants stamped structural drawings for your building, or accepts plans prepared under the code's prescriptive tables. Get the answer in writing.

3. Site hazards that decide the lane

• FEMA flood zone for the parcel (FEMA Map Service Center). Zone X is outside the special flood hazard area; zones A and V are inside it.
• Your town's published design values: ground snow load, wind speed, frost depth. In Massachusetts they are in the state code's town table (780 CMR 51.00 Table R301.2(2)).
• Coastal or shoreline location (Cape Cod and the Islands: wind-borne debris areas; coastal flood zones) and wildland-urban interface, if your town has one.
• Historic district, scenic road, or homeowners' association rules that govern appearance.

4. The building

• What it is for: cars, a shop, a studio, a one-bedroom rental, a parent's home. That sets the building type and the plan family.
• Footprint you can fit after setbacks and coverage, and whether one story or a garage with an apartment above.
• Garage door sizes (8 ft doors keep headers inside the code tables; 9 ft doors are a site-adapted option).
• Utilities: where water, sewer or septic, and electric will come from; whether a separate meter is wanted for an ADU.
• Roof: rafters from the tables, or a truss package from a manufacturer.

5. Documents to have before ordering a site-adapted set

• Survey or certified plot plan (or the best site drawing you have, marked as such).
• Deed or assessor's card with the parcel ID and owner of record.
• FEMA map panel number and zone.
• Any soil report, septic plan or wetlands map that exists for the lot.
• Your town's permit application and checklist for the building type, and any written answer the building department has given you.
• Photos of the spot from the house and from the street.