Eagle ADU Guide

ADUs permitted up to 700 square feet or 50% of primary dwelling square footage, whichever is less.

Investor implication: Eagle's 700 sqft cap is lower than Boise's 900 sqft post-ZOA25-000013 standard. On larger primary dwellings (1,400+ sqft), the 50% rule becomes the binding constraint. Underwrite ADU rent per sqft carefully—smaller units command higher per-sqft rents but absolute rent ceiling is lower.

In A (Agricultural) and A-R (Agricultural-Residential) zones, total structure footprint including ADU is capped at 10% of lot area.

Investor implication: This is the most-underestimated constraint on Eagle Foothills land plays. On a 2-acre A-zoned parcel (87,120 sqft), total footprint is capped at 8,712 sqft. A 3,000 sqft primary dwelling + 700 sqft ADU = 3,700 sqft footprint, leaving 5,012 sqft for garage, shop, barn, or other structures. Buyers routinely miss this and over-scope accessory buildings.

Owner-occupancy of either the primary dwelling or the ADU is required.

Investor implication: This requirement is in effect until July 1, 2026, when Idaho SB 1354 supersedes it. Cities over 10,000 population (Eagle qualifies) must remove owner-occupancy requirements at that point. Between now and July 1, 2026, ADU plays require owner-occupant underwriting or a hold-until-July strategy.

Cities over 10,000 population must allow at least one ADU per lot, may not impose owner-occupancy requirements, and may not impose blanket square-footage bans. HOAs may not add new ADU restrictions without written consent of all members; existing HOA bans remain enforceable.

Investor implication: Eagle's owner-occupancy requirement is superseded on July 1, 2026. The 700 sqft cap and the A/A-R 10% footprint cap are not blanket bans and remain enforceable. ADU plays acquired before July 1 with owner-occupant underwriting can pivot to dual-rental on July 1.