How much does a Kuna ADU cost?

At the same finish level the per-square-foot build cost is essentially identical, because most Treasure Valley contractors work Boise, Meridian, and Kuna out of the same crews — labor and material pricing settle at one regional market. A Standard-finish Kingfisher runs roughly $179k–$222k in Kuna or Boise. Where Kuna differs is the rent ceiling (slightly below the Boise core, which can shift the math on whether you build Essential, Standard, or Premium), Kuna's own permit and zoning specifics (verify the current size cap and Special Use Permit requirement with City of Kuna Planning & Zoning), and lot conditions — Kuna's larger parcels site an ADU more easily but can add utility-trenching cost on deep lots.

The plans physically fit Kuna lots — all six City of Boise pre-approved designs (Goldfinch, Waxwing, Kingfisher, Kestrel, Sandpiper, Osprey) are 695 sq ft or smaller, well under Boise's 900 sq ft ADU cap. But Kuna is a separate jurisdiction with its own Title 5 development code, and there is no formal reciprocity with Boise — your plan set still goes through City of Kuna plan-check, and Kuna's land-use table indicates an ADU may require a Special Use Permit in residential zones. Confirm Kuna's current maximum ADU size and the SUP requirement for your zone before assuming a Boise plan drops in unchanged. Because the drawings are already engineered, they typically move through review faster than a custom design.

What's confirmable from primary sources is the ACHD transportation impact fee — $5,803 per single-family dwelling effective 2026-03-01 (ACHD ordinance No. 254), which applies in Kuna because the city is inside Ada County. Kuna's own building permit and impact-fee schedule isn't surfaced cleanly in published online sources, so pull the current numbers directly from City of Kuna (kunacity.id.gov) or call the Planning & Zoning department before locking your budget. Per-tier dollar amounts depend on building valuation and the live fee schedule. We include all confirmed pass-through fees in the fixed-price contract once your parcel is verified.

The accessible portions of Kuna's Title 5 code don't clearly publish an owner-occupancy rule, so confirm the current requirement with City of Kuna Planning & Zoning for your zone. What's changing statewide: Idaho Senate Bill 1354, effective July 1, 2026, preempts city-level owner-occupancy mandates and some ADU restrictions for cities over 10,000 population. Kuna's population is roughly 31,000 by the county's 2024 estimate, so SB 1354 applies — cities are required to bring local code into compliance by February 1, 2027. Until Kuna revises its code, older provisions may still appear on the books, so verify the live status for your parcel before signing.

Kuna's published code excerpts don't surface a clear maximum ADU square footage, so confirm the current cap with City of Kuna Planning & Zoning. For reference, neighboring Boise raised its ADU cap to 900 sq ft (the lesser of 900 sq ft or 50% of the primary dwelling) in its December 2023 Modern Zoning Code, and Meridian uses the same 900 sq ft limit. All six City of Boise pre-approved plans are 695 sq ft or smaller, so they stay under those caps comfortably — but Kuna sets its own standard, and Idaho SB 1354 (effective July 1, 2026) constrains how restrictive cities over 10,000 population can be. Get Kuna's current number in writing before you finalize a plan.

Kuna's 1-bedroom rents sit at or slightly below the Boise core. Listing aggregators in mid-2026 put the Kuna 1-bedroom figure in roughly the $1,400–$1,620/month range — Apartments.com near $1,421 and Apartment Finder near $1,618 — versus a Boise 1-bedroom baseline around $1,479–$1,503. Kuna's rental-comp base is thinner than Boise's, so these figures move more from listing to listing; treat them as a directional band, not a precise median, and pull live comps for your block. On a $200k Standard-finish Kingfisher, a modestly lower rent ceiling slightly trims gross yield versus Boise, but Kuna's larger lots and strong commuter demand can offset it. Run your specific plan, finish, and rent inputs through the ROI calculator before committing.