Idaho’s New ADU Law Expands Housing Options as Cities Update Zoning Rules
Idaho has introduced new statewide zoning requirements designed to make accessory dwelling units (ADUs) easier to build in qualifying residential areas. Senate Bill 1354 took effect on July 1, 2026, limiting the ability of covered cities to prohibit ADUs and establishing standards for their approval.
The law is part of a broader set of housing measures aimed at expanding residential options as communities address affordability and growth. Cities, including Coeur d’Alene, are reviewing their local regulations to determine how existing zoning rules must change to comply with the new requirements.
What the New ADU Law Means for Homeowners
An accessory dwelling unit is a secondary residential unit located on the same lot as a primary single-family home. It may be created within an existing house, attached to the main dwelling, or built as a separate structure.
ADUs can provide housing for family members or tenants and may offer homeowners an additional source of rental income, subject to applicable laws and restrictions.
Under SB 1354, covered cities must allow qualifying ADUs in residential areas rather than prohibit them outright. The law also requires compliant projects to receive administrative approval when they meet established land-use requirements, without discretionary approval processes.
These changes are intended to reduce certain zoning barriers while retaining applicable building, safety, and land-use standards.
Key Provisions of Senate Bill 1354
The legislation establishes several requirements for local governments:
- ADU eligibility: Covered cities cannot ban ADUs in residential zoning areas and must allow qualifying internal and detached units on eligible lots.
- Size standards: Cities cannot impose ADU size limits below the minimum thresholds established by state law.
- Parking requirements: The law restricts mandatory off-street and guest parking for ADUs, subject to applicable statutory provisions.
- Setbacks and height: The legislation limits certain setback and height restrictions that could prevent otherwise qualifying ADUs from being built.
- Administrative approval: Projects that meet established land-use requirements must be approved administratively rather than subjected to discretionary approval.
- Homeowners associations: The law also changes how certain HOA restrictions on ADUs may be adopted or enforced, while retaining distinctions for existing property covenants and reasonable rules.
The exact requirements depend on the statutory provisions and circumstances of the property. Homeowners should not assume that every lot can accommodate an ADU without additional review.
Coeur d’Alene Reviews Its Local Regulations
Coeur d’Alene has been examining how the new state requirements affect its municipal code.
During a workshop reported by the Coeur d’Alene Press on October 14, city officials discussed questions surrounding SB 1354, including ADU size limits and parking requirements.
The city’s existing code lists a maximum ADU size of 800 square feet and a limit of 75% of the primary dwelling’s floor area, excluding the garage. The new state law restricts cities from setting ADU size limits below its statutory thresholds, creating a need to reconcile existing local provisions with state requirements.
The law also addresses parking and other development standards, although certain exceptions may apply. Local officials must determine how the state requirements interact with existing regulations and the circumstances of individual properties.
The review illustrates why homeowners should check the current rules with their local planning department rather than relying exclusively on older municipal code language.
Other Idaho Housing Reforms
SB 1354 is part of a wider set of Idaho housing measures, but several related reforms were enacted through separate legislation.
Other measures address starter-home subdivisions and the siting of manufactured homes in residential areas. These laws have their own requirements and implementation processes.
The distinction matters because the rules governing smaller subdivisions, manufactured housing, and accessory dwelling units are not identical. Property owners and developers should identify the applicable statute before making decisions about a proposed project.
What Buyers, Sellers, and Investors Should Know
For homeowners, an ADU may provide a way to accommodate relatives, create additional living space, or generate rental income. However, the feasibility of a project depends on the lot, construction costs, utility connections, building codes, and the property’s applicable restrictions.
For buyers, properties with the potential to accommodate an ADU may offer additional flexibility. Prospective purchasers should verify zoning eligibility and estimated development costs before assigning value to a potential second unit.
Developers and investors should also monitor local implementation. Changes to zoning requirements can expand the range of eligible projects, but they do not eliminate construction expenses or guarantee that a project will be financially viable.
What Happens Next?
Cities are reviewing their comprehensive plans and land-use regulations to align local requirements with Idaho’s new ADU law. Coeur d’Alene’s review highlights the practical questions that can arise when state legislation changes existing local standards.
Anyone considering an ADU or purchasing property for that purpose should contact the relevant planning department and review the current state requirements before beginning construction or making a financial commitment.