Eagle · ADU Cost 2026
Updated: May 2026
Eagle ADUs run $115k–$345k+ turnkey in 2026, with most builds landing at the Standard or Premium end of the range. Larger lots, EASD design review, HOA-layered review, and an owner-occupancy rule that still applies — the numbers and the rules below.
An Eagle Idaho ADU costs $115k–$345k turnkey in 2026, but the typical Eagle build lands at the Standard or Premium finish end of the range. Per-sqft labor and materials are similar to Boise — the differentiators are EASD design review for architectural compatibility, HOA-layered review in subdivisions like Banbury and Two Rivers, and the larger lots that often invite a Kestrel 2-bed (695 sq ft, $245k+ turnkey) rather than the smaller plans. Eagle 1BR median rent runs $1,350, 2BR $1,625 per Apartment List / Zumper (May 2026).
Eagle is the most design-reviewed and the most affluent of the four cities surrounding Boise. That combination — larger lots, architectural compatibility requirements, and a buyer pool that expects Premium spec — pushes the cost mix up. Four reasons the same plan you'd build for $185k in Boise might land at $215k–$230k in Eagle.
Eagle's design code requires the ADU's roof pitch, siding profile, window style, and color palette to match the primary residence. That typically means premium lap siding (not vinyl), real trim returns, divided-light windows, and matching stone or stucco accents — Standard finish at the floor, Premium more common.
Eagle lots in Banbury, Two Rivers, Eagle Hills, and the Foothills routinely run a quarter-acre or more. The Kestrel (695 sq ft, 2BR) fits cleanly where it would crowd a Boise infill lot — and once you're at 695 sq ft, the per-unit budget naturally climbs into the $245k–$345k zone.
Eagle's median home value is $700k+ per Zillow ZHVI. Homeowners building an ADU there are typically building for parents, adult children, or premium long-term renters — not the cheapest legal box. Standard-to-Premium finish dominates the bid mix, with Essential rare.
The Eagle Architecture and Site Design Book (EASD) review runs alongside HOA architectural committees in Banbury, Two Rivers, and Eagle Hills. Plan on 4–8 weeks of layered review, and budget for the exterior revisions that come out of it — they're rarely free.
All six of Boise's pre-approved plans fit under Eagle's ~900 sq ft ADU cap, so the same catalog applies — but Eagle's EASD review typically requires exterior modifications to match the primary residence. The per-sqft math below is the same Essential / Standard / Premium model used on /adu-cost-boise; expect Eagle builds to come in 5–10% over those figures once HOA-driven exterior upgrades are priced in.
The most common Eagle pick: the Kestrel (695 sq ft, 2BR) at Premium finish — $300k–$374k turnkey — for multigenerational use or premium long-term rentals where the Eagle rent ceiling supports the spec.
| Plan | Type | Size | Beds | Essential | Standard | Premium |
|---|---|---|---|---|---|---|
| The Goldfinch | Type A | 280 sqft | Studio | $86k–$107k | $102k–$127k | $121k–$151k |
| The Waxwing | Type B | 396 sqft | Studio | $121k–$151k | $144k–$180k | $171k–$213k |
| The Kingfisher | Type C | 491 sqft | 1BR | $150k–$187k | $179k–$223k | $212k–$264k |
| The Kestrel | Type D | 695 sqft | 2BR | $213k–$265k | $253k–$315k | $300k–$374k |
| The Sandpiper | Type G-1 | 396 sqft | Studio | $121k–$151k | $144k–$180k | $171k–$213k |
| The Osprey | Type G-2 | 376 sqft | Studio | $115k–$143k | $137k–$171k | $162k–$202k |
Iron Crest Remodel (Idaho contractor license RCE-6681702) is the licensed builder behind these numbers — service area includes Eagle, with per-project bids reconciled against the City of Eagle and ACHD fee schedules at quote time.
Eagle layers two design-review processes (EASD plus HOA) on top of standard Ada County permitting, and it still enforces owner-occupancy and minimum off-street parking — rules Boise dropped in its 2023 zoning rewrite. Six line items every Eagle ADU budget needs to account for.
Eagle sits inside Ada County Highway District. ACHD's residential transportation impact fee is $5,803 per single-family dwelling unit, effective March 1, 2026 under ACHD ordinance No. 254. ADU-specific reductions, if any, should be confirmed with ACHD directly. Source: ACHD via KIVI TV, 2026-03-01.
Eagle requires ADU designs to comply with one of nine architectural themes in the EASD. Compatible exterior materials, roof pitch, window style, and overall character relative to the primary residence are all in scope. Practical impact: 2–4 weeks of added review and, frequently, exterior revisions before sign-off.
Banbury, Two Rivers, and Eagle Hills each operate their own architectural review committee with covenants that often go beyond city EASD requirements. Typical add: 1–3 weeks per HOA cycle. Submitting to the HOA before the city is the standard sequence so any required revisions land before plan check.
Unlike Boise — which removed its owner-occupancy rule under the 2023 Modern Zoning Code — Eagle still requires the property owner or an immediate family member to occupy either the primary residence or the ADU. Idaho SB 1354 preempts this rule statewide effective July 1, 2026; until Eagle's code is updated, the rule is on the books.
Eagle requires at least one off-street parking space for the ADU, not located in the public right-of-way or required setbacks. This is a real difference from Boise, which eliminated the extra-parking requirement in the 2023 rewrite. Plan the site layout accordingly — a 200 sq ft pad isn't trivial on a tight rear yard.
Eagle publishes per-tier residential permit fees via Resolution 23-01 (PDF on cityofeagle.org). Per-valuation dollar amounts aren't reproduced here — pull the current schedule from the city or call Eagle Building (208-489-8760, building@cityofeagle.org) before locking your budget.
Per-tier permit dollar amounts are available from cityofeagle.org (Resolution 23-01 fee schedule) — pull the current schedule before locking your budget, since the fee resolution dates to early 2023 and may have been revised.
Eagle's premium positioning is a fit for specific use cases — and a poor fit for others. Four scenarios where the EASD review and higher build spec are worth it.
Eagle's owner-occupancy rule is a non-issue if you live on the property. A Kestrel for parents, a Kingfisher for a long-term tenant, or a Sandpiper for a guest house all work cleanly when the homeowner is the principal occupant.
Eagle's larger lots accommodate the 695 sq ft Kestrel without the siting compromises a Boise infill lot forces. Two bedrooms, real living room, single-level for accessibility — the most common Eagle pick for housing aging parents or an adult child.
West Ada School District boundaries through Eagle pull family-renter demand at the 2BR end of the market. A Kestrel detached unit on an Eagle lot rents to a family on a 12-month lease, not a transient nightly tenant.
If you already know what your house looks like and care about matching it, EASD review feels like a sanity check rather than a hurdle. The design-review system rewards homeowners who came in with a clear architectural intent.
Three situations where the Eagle premium isn't worth paying for — and where a sibling Treasure Valley city gets you to the same outcome with less friction.
Eagle's pre-SB 1354 owner-occupancy rule effectively blocks pure investor plays. Until July 1, 2026 (and until Eagle updates its code), Boise is the cleaner path for an investor — no owner-occupancy requirement, larger pre-approved plan catalog, faster permit cycle.
Eagle's positioning pushes the bid mix toward Standard and Premium. If you're solving for the cheapest legal ADU and the math only works at Essential finish, Boise or Meridian gets you to the budget without the design-review premium. See /adu-cost-boise for the Essential-tier numbers.
Layered EASD + HOA review adds 4–8 weeks on top of city plan check. If permit speed is the constraint, Boise's pre-approved program (3–5 weeks per the City) and Meridian's typical 2–3 week cycle both clear faster than Eagle.
ACHD impact fee figures cite the ACHD ordinance No. 254 (effective 2026-03-01). Eagle code references cite Eagle City Code Title 8 via cityofeagle.org. Rent comps from Zumper (May 23, 2026).
Eagle ADUs run $115k–$345k+ turnkey in 2026, with most builds landing at the Standard ($405/sqft) to Premium ($480/sqft) end of the range. The Kestrel (695 sq ft, 2BR) at Premium finish — the most common Eagle configuration — runs roughly $300k–$374k turnkey. Add 5–10% over an equivalent Boise build for HOA-driven exterior upgrades (stone wainscot, premium siding, matching trim) that come out of EASD architectural compatibility review.
Yes — as of May 2026, Eagle City Code Title 8 still requires either the primary residence or the ADU to be owner-occupied by the property owner or an immediate family member. Idaho Senate Bill 1354 preempts city-level owner-occupancy rules statewide effective July 1, 2026, and Eagle has until February 1, 2027 to update its code. Until that update lands, the rule applies. Confirm current status with Eagle Planning (208-489-8760) before relying on the preemption.
Plan on 4–8 weeks of layered design review on top of standard Eagle plan check — 2–4 weeks for EASD compliance review against the Eagle Architecture and Site Design Book, and 1–3 weeks per HOA architectural committee in subdivisions like Banbury, Two Rivers, and Eagle Hills. The practical sequence is HOA first, then city EASD review, then standard plan check. Revisions are common at each step.
Not plug-and-play. Eagle does not have a formal reciprocity agreement with Boise, and EASD architectural compatibility review effectively prevents using a Boise pre-approved plan as-drawn — even a well-detailed Kestrel typically needs exterior re-skinning (siding profile, roof pitch matching, trim color, window style) to satisfy compatibility with the primary residence. The interior plan can carry over; the exterior almost always needs Eagle-specific work. Confirm requirements with Eagle Planning before assuming reuse.
Median Eagle 1BR rent is $1,350/month per Zumper (May 23, 2026), with 2BR at $1,625/month. Zumper notes Eagle 1BR rents up 22% year-over-year and 2BR up 8%. Other sources (RentCafe, ApartmentList) put the figures higher — RentCafe at $1,561 and ApartmentList north of $1,800 — reflecting Eagle's larger single-family rental mix. For long-term-rental ROI math on a finished Eagle ADU, the realistic 1BR achievable is $1,400–$1,800 depending on neighborhood and finish.
Three reasons. First, EASD architectural compatibility pushes the exterior package toward higher-grade siding, real trim returns, and matching roof details — that's a real materials premium over a Nampa Standard finish. Second, Eagle's larger lots invite larger plans (Kestrel territory) where Nampa's 500 sq ft cap forces studios. Third, the buyer pool in Eagle expects Premium finish at the rent ceiling Eagle commands — a $1,150 Nampa 1BR doesn't justify a Premium spec; a $1,800 Eagle 1BR usually does.
Sibling city cost pages, the Eagle service-area deep-dive, and the tools and plans homeowners use most when scoping an Eagle ADU build.
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Start with a free lot check — EASD compatibility notes, HOA-review sequencing for Banbury, Two Rivers, or Eagle Hills, and the right cost path for your goals. Or call (208) 297-2036.
