Summary of Caldwell City Code Title 10 Article 12 (ADU regulations · 2025 update; owner-occupancy removed; 900 sqft / 2BR cap) as it applies in Caldwell. Reference: https://library.municode.com/id/caldwell.
Code evolves continuously. Verify at the official source (https://library.municode.com/id/caldwell) before any development decision.
Applicable code
Code references active as of publication. Verify current standards at the official source before any development decision.
Cities with populations over 10,000 must allow at least one accessory dwelling unit per single-family lot. Local governments may not require owner occupancy of either the primary dwelling or the ADU. Local governments may not impose blanket square-footage prohibitions on ADUs. Homeowners associations may not adopt new restrictions on ADUs without written consent of all members; existing HOA restrictions remain enforceable.
Caldwell has no explicit local ADU ordinance codified in Chapter 10 (Zoning Regulations). The city relies on Idaho SB 1354 state preemption. Local administrative standards for ADU size, setbacks, and parking are administered by the Building Safety Division but are not codified in municipal code. Verify all local standards in writing with Building Safety Division before development.
Verify at Caldwell Building Safety Division Administrative Standards →Renew analysis
State law guarantees at least one ADU per lot in Caldwell as of July 1, 2026. No owner-occupancy requirement means investors can hold both units as rentals. Existing HOA bans remain enforceable — verify CC&Rs before acquisition. New subdivisions platted after July 2026 cannot prohibit ADUs without unanimous consent.
Caldwell's ADU framework relies on state preemption rather than detailed local code. Investors must verify size caps, setback requirements, and parking standards directly with the Building Safety Division before underwriting. Lack of explicit local code creates uncertainty — confirm all standards in writing before LOI.