Home Addition cost
What a home addition involves, what it runs in each state we build in, and the metro-by-metro guides with live pricing.
What the project involves
A home addition adds finished square footage to your house — a primary suite, a larger kitchen and family room, or a second story. It is new construction attached to an old one: foundation, framing, roof, envelope, mechanical, electrical and finish, plus the tie-in work where new meets existing.
Additions are priced per square foot against the local build rate, with a size factor (small additions cost more per foot than large ones) and multipliers for finish level, site conditions and structural complexity such as second stories or bearing-wall removal.
Across our four states
Live planning ranges from the current pricing version. Land, design and permit fees, utility connections and unusual soils are priced separately.
| State | Priced at | home addition, standard finish |
|---|---|---|
| Washington | Seattle · 1,000 sq ft (exact) | $410K – $560K |
| Idaho | Boise · 1,000 sq ft (exact) | $285K – $385K |
| Montana | Billings · 1,000 sq ft (exact) | $248K – $335K |
| Arizona | Scottsdale · 1,000 sq ft (exact) | $375K – $520K |
Home Addition cost by metro
Metro guides for this project type are being prepared — use the calculator for a live range in your ZIP.
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