We priced 38 ADU designs line by line in the LEVA configurator in October 2026. They cost $44,109 to $122,501 to build, with a median of $79,354, about $133 per sq ft. Materials are about two thirds of the total and labor one third; land, a contractor's markup and financing are not included.
If you are pricing an accessory dwelling unit, the estimates you find online are all over the place, and few of them show where the money actually goes. So we took the numbers from our own tool instead: 38 ADU designs priced line by line in the LEVA ADU configurator in October 2026, from a 288 sq ft studio to a 1,040 sq ft three-bedroom unit, each with a full bill of materials and labor for a specific size, roof and city.
The short answer
- The 38 budgets run from $44,109 to $122,501. The median is $79,354, or about $133 per square foot.
- Materials make up about two thirds of the total, labor about one third.
- These are budgets for the building itself, with labor at local trade rates. Land, a general contractor's markup and financing are not included.
| Size | Designs | Median total | Median cost per sq ft | Median work hours |
|---|---|---|---|---|
| Under 450 sq ft | 12 | $58,200 | $157 | 750 |
| 450 to 700 sq ft | 10 | $75,900 | $140 | 1,020 |
| 700 sq ft and up | 16 | $95,400 | $123 | 1,300 |
What drives ADU construction cost
1. Size, but not in a straight line
A bigger ADU costs more in total, yet less per square foot. In our set the small units came out at a median of $157 per sq ft and the large ones at $123. The reason is simple: every unit needs a kitchen, a bathroom, a service connection, a foundation edge and a permit, whether it has 300 or 900 square feet. Those fixed pieces weigh more on a small floor area.
2. Bedrooms, bathrooms and the kitchen
Wet rooms are where plumbing, tile, fixtures and ventilation pile up. The studios in our set had a median budget of $58,172, the one-bedroom units $77,906 and the two-bedroom units $94,307. A second bathroom is one of the biggest single jumps you can make.
3. The choices inside the same footprint
Three of the designs share the same 16 x 24 ft footprint and the same gable roof, and their budgets still range from $44,109 to $60,564. Windows and doors, cladding, insulation, finishes, heating and local prices all move the total. This is why a price per square foot is only a starting point: two ADUs of the same size can be $15,000 apart.
4. Foundation and site
A slab on grade, piers or a crawl space, the slope of the lot and how far the water, sewer and power lines have to run all change the base of the budget. Excavation and trenching are real line items, not rounding errors.
5. Soft costs
Site survey and soil testing, engineering and documentation, zoning approval, building and trade permits, impact fees, utility connections and tap fees, inspections, sales tax on materials, a contingency reserve and waste removal. The LEVA budget lists each of these as its own line so none of them is forgotten. What they cost depends heavily on your city, so check them with your local building department.
6. Who does the work
Labor is about a third of the budget, and a mid-size ADU takes roughly a thousand work hours. Every task you take on yourself comes straight off that part of the bill.
An itemized example
Take the 20 x 30 ft one-bedroom unit in San Diego, CA: 600 sq ft with a gable roof. Its budget is $83,792, of which $56,317 is materials and $27,474 is labor, about 1,038 work hours, or roughly $140 per sq ft.
In the configurator that total is not one number but a bill grouped the way the building goes up:
- site and soft costs (survey, permits, fees, connections, inspections)
- excavation and foundation
- floor structure
- wall framing, sheathing, insulation and membranes
- windows and doors
- exterior cladding and trim
- roof structure, underlay, covering and flashing
- interior walls and ceilings
- electrical, heating and cooling, water and drainage
- kitchen, bathroom and finishes
Every line has a quantity, a unit and a price, down to the screws, tapes and sealants that hold the visible parts together. You can open this exact design here: 20 x 30 ft ADU in San Diego.
Five ways to bring the cost down
- Keep the shape simple. A plain rectangle under one roof line needs less framing, flashing and labor than a plan with jogs and corners.
- Put the wet rooms back to back. A kitchen and bathroom that share a wall share the plumbing runs too.
- Use standard window and door sizes, and fewer, well-placed openings rather than many small ones.
- Do the finishing work yourself. Painting, flooring, trim and fixture installation are the easiest hours to take off a third of the budget that is labor.
- Price it before you commit. Change one thing at a time and watch the total, then ask for quotes on the big packages (foundation, roofing, electrical) against the itemized list instead of a lump sum.
Price your own ADU
Every number above comes from the LEVA ADU configurator. Change the size, layout, roof, windows and finishes, set your location, and the itemized budget follows every change, line by line. All 38 reference designs are listed in a table at the bottom of the ADU page, each one a click away from opening in 3D.
How these figures were made: 38 reference designs priced in the LEVA ADU configurator in October 2026, with material and labor prices of that month. They are budgets, not bids. A contractor's markup, land, financing and unusual site conditions are not included.
