"They were the only builder who walked our lot before quoting. Pricing held all the way through."
Marcus & Lena
Eagle, ID · Kingfisher 491 detached
Cost · Transparent Pricing
Know your Boise ADU number before you call
Real Boise build pricing for 2026, modeled by square footage and finish level. Drop in your inputs and see a defensible range in under a minute.
Cost Calculator
Model your ADU build
Drag the slider, pick a finish level, see a real Boise build range.
600 sq ft
280 (studio)900 (2-bed)
Estimated total build
$219,000–$272,000
Estimated financing
~$1,460/mo
Based on 80% LTV at typical Idaho construction-loan rates. Subject to lender terms and final scope.
Estimate includes site work, foundation, framing, MEP, finish, and permits. Excludes lot prep on unusual sites and utility upgrades.
Optional: get this estimate by email
Want this estimate plus a real fixed-price quote?
We'll send your numbers and follow up within 24 hours with a quote on your specific lot. No spam, no list, one human reply.
Reference table
Build ranges by plan + finish
Same math the calculator uses, laid out for quick scanning. All ranges are total fixed-price build cost in 2026 Treasure Valley dollars.
| Plan | Sqft | Essential ($340/sqft) | Standard ($405/sqft) | Premium ($480/sqft) |
|---|---|---|---|---|
| Goldfinch | 280 | $86,000–$107,000 | $102,000–$127,000 | $121,000–$151,000 |
| Waxwing / Sandpiper | 396 | $121,000–$151,000 | $144,000–$180,000 | $171,000–$213,000 |
| Kingfisher | 491 | $150,000–$187,000 | $179,000–$223,000 | $212,000–$264,000 |
| Kestrel | 695 | $213,000–$265,000 | $253,000–$315,000 | $300,000–$374,000 |
Ranges include site work, foundation, framing, MEP, finish, and permits. Excludes lot prep on unusual sites and utility upgrades.
New · Investor tool
Want yield math too? The ROI Calculator models gross yield, monthly cash flow after debt service, payback, and 10-year cash-on-cash on top of the build cost.
Reviews
Real Idaho homeowners, real builds.
"Permits, design, build — one team handled it. We rented to a long-term tenant the week we got the C of O."
Sara K.
North End, Boise · Kestrel 695 detached
"Turned the back of our garage into a real apartment for my dad. Thoughtful at every step."
The Williams family
Meridian, ID · Garage conversion
Reviews from completed Boise / Treasure Valley builds. Full names and project references available on request.
Licensed · Bonded · Insured · Idaho-Based
- Licensed & Insured (DBA partnership)
- Boise Building Permit Office filings
- Boise pre-approved plan specialists
What's included
Everything in our fixed price
The estimate above bakes in everything below. The exclusions are the few things outside our control — you'll see them spelled out the same way in your final fixed-price contract.
Included
- Site work + foundation
- Framing, sheathing, roofing
- Electrical, plumbing, HVAC
- Insulation, drywall, flooring
- Cabinets, counters, fixtures
- Boise / Treasure Valley permits
Not included
- Land cost (you already own the lot)
- Utility line upgrades to the property
- Excessive site prep on steep or rocky lots
- Furniture, appliances beyond standard kitchen
FAQ
Cost questions
How accurate is this estimate?
It's a planning range — typically within 10–15% of the final fixed price for most Boise lots. Actual price depends on lot conditions (slope, soil, utility distance), final finish picks, and current material pricing.
What's the difference between Essential, Standard, and Premium?
Essential is durable builder-grade — vinyl plank, laminate counters, builder-grade fixtures. Standard adds quartz, LVP, mid-range fixtures, tile bath. Premium adds tile floors, designer cabinets, upgraded windows, hardwoods.
Why does cost-per-square-foot drop on bigger ADUs?
Fixed costs (foundation, kitchen, bathroom, permits) get spread over more square feet. A 280 sq ft Goldfinch and a 695 sq ft Kestrel both have one kitchen and one bathroom — but the Kestrel divides those costs over 2.5× the area.
Are pre-approved plans cheaper to build?
Construction cost is similar — what you save is design fee ($8–15k) and permitting time (4–8 weeks). The pre-approved plans are also designed to be efficient to build, so labor is often slightly lower too.
Can I finance this against my existing home equity?
Most Boise homeowners use a HELOC, a cash-out refi, or a construction loan. We've worked with lenders who specifically finance ADU builds. We can introduce you to a couple if it helps.
Want a property-specific number?
The calculator gives you a planning range. For a real fixed-price quote, send us your address and what you're hoping to build — we'll come back within 24 hours.