Boise adu construction pricing per square foot
ADU Construction cost per square foot in Boise, Idaho in 2026.
Low
$151,500
Average
$227,300
High
$303,000
Boise crews quote about $255 – $505 per square foot.
Multiply local unit rates by your real measurements.
What drives adu construction prices in Boise
Local labor, permitting and climate move Boise prices away from the national average.
Labor market
Licensed trade labor in Boise runs about 101% of the national average, and the best crews book out fastest in spring and early summer.
Permits
Most Boise, ID projects that change structure, electrical, plumbing or mechanical systems need a permit from the local building department; cosmetic work usually does not.
Climate
Idaho weather drives material choices here, so ask contractors what they install most often in Boise and why.
Boise unit pricing by material
Ways to lower your Boise price
- Use pre-approved ADU plans where your city offers them — saves months and design fees.
- Detach only if required; attached and conversion ADUs cost far less.
- Collect three written bids on an identical scope — spreads of 20–40% are normal.
- Book in the off-season and stay flexible on the start date to save 5–15%.
- Bundle nearby work into one mobilization so you only pay setup and travel once.
- Ask what the contractor would change to cut 10% without hurting durability.
Boise questions
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