Estimating additions and ADUs
Prices for additions and ADUs, what drives the cost and how to structure the estimate, for remodeling contractors bidding the work.
An addition is a small new building tied to an old one. Foundation, framing, roofing, every mechanical trade and the finishes go in one bid, plus the work of tying into the existing house. Structure the estimate by phase so nothing falls between trades.
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Room addition prices
Q4 2026 pricing. National figures are the median of 50 metro areas. Ranges are rounded to the nearest $50, or $100 from $5,000 up.
1 story over a basement
$45,700 to $302,100
150 to 1,000 square feet
2 story over a basement
$69,300 to $464,400
150 to 1,000 square feet
Labor and materials
For a typical job, nationally. Labor rates move more from place to place than materials do.
How the estimate is structured
The cost categories an estimate for this work breaks into:
- Project preparation
- Excavation
- Concrete
- Floor framing
- Wall framing
- Roof framing
- Roofing and gutters
- Exterior doors
- Wood windows
- Exterior trim
- Siding and awnings
- Heating, ventilation, air conditioning
- Electrical
- Insulation
- Wall coverings
- Ceiling coverings
- Interior doors
- Interior trim, stairs and accessories
- Floor covering
- Exterior painting
- Interior painting and wallpaper
- Project finalization
What drives the cost
Foundation
A slab, a crawlspace and a full basement price very differently, and slope, soil and access change the excavation.
Size and stories
A second story adds finished area over the same foundation and roof, so the cost per square foot often drops. Stairs and structure add some of it back.
Kitchens and baths
Rooms with plumbing cost the most per square foot. A bedroom addition and an owner's suite with a full bath are different jobs.
Tying into the house
Opening the exterior wall, matching the roofline and siding, and extending heating, cooling, electrical and plumbing. Check whether the panel and the HVAC system can carry the new load.
Finish level
Siding, roofing, windows, flooring and fixtures set the finish. An economy ADU and a luxury one can share a footprint and land far apart on price.
Design, permits and utilities
Plans, engineering, permits and fees vary by jurisdiction. A detached ADU also needs utility runs from the main house.
Building the estimate
Structure it by phase
- Site work and excavation
- Foundation: slab, crawlspace or basement
- Framing: floors, walls and roof
- Roofing, gutters and downspouts
- Windows and exterior doors
- Siding, soffit and fascia
- Plumbing, electrical and HVAC, including the tie-in to existing systems
- Insulation and drywall
- Interior doors, trim, flooring and paint
- Kitchen and bath fixtures, when they're part of the job
Phases make the bid easy to check and easy to schedule, and they match how your subs quote.
Additions and ADUs aren't the same bid
An attached addition shares a wall, a roofline and the house's systems. A detached ADU is a whole small house: its own foundation, roof, kitchen, bath, heating and cooling, plus utility trenching from the main house. An ADU over a garage stacks living space on a new garage.
List what you can't price yet
Engineering, permit fees and utility connection charges often aren't known at bid time. List them as allowances or exclusions so the client knows they're coming.
Addition and ADU templates in Clear Estimates
Templates cover one and two story additions over a basement, owner's suite additions, bathroom additions, and ADUs above a garage or detached, from economy to luxury finish.
Other projects
Each with its own price table, nationally.
Local pricing
Prices for additions and ADUs in each metro area, against the national median.
- New York, NYPrices run 19% above the national median.
- Chicago, ILPrices run 24% above the national median.
- Atlanta, GAPrices run 2% below the national median.
- Washington, DCPrices run 1% above the national median.
- Dallas, TXPrices run 9% below the national median.
- Boston, MAPrices run 17% above the national median.
- Minneapolis, MNPrices run 11% above the national median.
- Detroit, MIPrices run 4% above the national median.
- Seattle, WAPrices run 16% above the national median.
- Pittsburgh, PAPrices run 2% above the national median.
- Los Angeles, CAPrices run 9% above the national median.
- Philadelphia, PAPrices run 11% above the national median.
- Denver, COPrices run 2% below the national median.
- Baltimore, MDPrices run about the national median.
- Miami, FLPrices run 9% below the national median.
- Charlotte, NCPrices run 9% below the national median.
- St. Louis, MOPrices run 3% above the national median.
- Houston, TXPrices run 13% below the national median.
- San Francisco, CAPrices run 24% above the national median.
- Tampa, FLPrices run 13% below the national median.
- Phoenix, AZPrices run 3% below the national median.
- Orlando, FLPrices run 11% below the national median.
- Cincinnati, OHPrices run 4% below the national median.
- Cleveland, OHPrices run 3% below the national median.
- Kansas City, MOPrices run 2% above the national median.
- Columbus, OHPrices run 6% below the national median.
- Indianapolis, INPrices run 6% below the national median.
- Raleigh, NCPrices run 10% below the national median.
- Virginia Beach, VAPrices run 9% below the national median.
- Riverside, CAPrices run 5% above the national median.
- San Diego, CAPrices run 6% above the national median.
- Portland, ORPrices run 6% above the national median.
- San Jose, CAPrices run 21% above the national median.
- San Antonio, TXPrices run 15% below the national median.
- Grand Rapids, MIPrices run 5% below the national median.
- Jacksonville, FLPrices run 12% below the national median.
- New Orleans, LAPrices run 12% below the national median.
- Albany, NYPrices run 1% above the national median.
- Richmond, VAPrices run 9% below the national median.
- Las Vegas, NVPrices run 2% above the national median.
- Providence, RIPrices run 4% above the national median.
- Memphis, TNPrices run 11% below the national median.
- Rochester, NYPrices run 2% above the national median.
- Greenville, SCPrices run 10% below the national median.
- Bridgeport, CTPrices run 10% above the national median.
- Worcester, MAPrices run 10% above the national median.
- Syracuse, NYPrices run 1% below the national median.
- Sacramento, CAPrices run 8% above the national median.
- Nashville, TNPrices run 12% below the national median.
- Milwaukee, WIPrices run 4% above the national median.
Questions
What should a room addition estimate include?
Every phase from site work to finish: excavation and foundation, framing, roofing, windows and doors, siding, plumbing, electrical and HVAC with the tie-in to the house, insulation and drywall, then trim, flooring and paint.
How is an ADU estimate different from an addition?
A detached ADU has everything a small house has: its own foundation and roof, a kitchen and bath, its own heating and cooling, and utility runs from the main house. An addition shares much of that with the house it's attached to.
How do I handle many trades in one estimate?
Break the estimate into phases, each with its own lines and labor. You can check the total and each trade on its own, and drop in a sub's quote where you have one.
Can I start from a template and adjust it?
Yes. Use a template as the starting point and change any line to match the site, the plans and your subs' quotes. The template gets the structure right; your site walk gets the details right.
Estimate additions and ADUs with prices for your area
No contract. No setup fees. Cancel anytime.