Backyard ADU 320 sq ft
Plan a guest cottage, home office or rental ADU of around 320 sq ft in your backyard, with exact measurements and drawings to bring to your building department.
Design my ADU
01
A small shed or studio without plumbing may be exempt from a permit in many places (often under 120–200 sq ft). Once it has a kitchen and bathroom for living, it is an ADU and needs a building permit and zoning approval.
02
Fit a kitchenette, bathroom and sleeping area in feet and inches, try a loft under a gable roof and furnish with real dimensions.
03
Enter your lot size and see footprint, lot coverage and setbacks from property lines directly in the sketch.
04
With the paid version you get a site plan, floor plan, elevations with grade line and a section with ridge height, printed to scale.
THE RULES AT A GLANCE
Typical limits for detached ADUs – your city's zoning code and state ADU law decide.
Many cities allow detached ADUs from about 600 to 1,200 sq ft, often capped by a share of the main house or lot coverage.
Detached ADUs are often limited to around 16 ft with 4–5 ft side and rear setbacks. California sets statewide minimums.
A studio or office without kitchen may count as an accessory structure. With kitchen and bathroom for living it is an ADU and needs a permit.
Water, sewer and power connections need separate permits. HOA covenants may add their own limits.
THREE WAYS TO USE 320 sq ft
Starting points you can redraw in feet and inches and furnish with real dimensions.
Kitchenette, accessible bathroom and a loft above, keeping the main floor open for living.
Kitchenette, bathroom and a flexible space – office by day, guest room by night.
Open space, large windows to the yard, storage wall and half bath.
FROM SKETCH TO SITE
Enter your lot, try volume and roof shape and see setbacks from property lines.
Fit kitchen, bathroom and sleeping area with real furniture.
Site plan, floor plan, elevations and section printed to scale.
Check zoning and HOA, apply for the building permit and book inspections.
THE DRAWING SET
Four drawings straight from your model – with the same dimensions everywhere.
Position on the lot with setbacks to property lines.
Rooms, fixtures, doors and windows.
All four sides with grade line and materials.
Ceiling height, ridge height and roof pitch.
Illustrations are simplified examples. ADU rules vary by state, county, city and HOA.