ADU Regulations in Los Alamitos, California (2026)

Regulations at a glance

Local rules & notes

Sound Transmission Requirement: Common walls and floor/ceiling assemblies between an attached ADU and the primary dwelling must meet a sound transmission rating of STC 50 or higher. Specific Fire Flow Availability: Referral to the Fire Department is required unless specific GPM (Gallons Per Minute) flow rates are met, ranging from 500 to 1,250 GPM depending on the hazard zone. Vapor Retarder for Garage Slabs: Conversions of existing garage slabs require a vapor retarder; if one does not exist, specific approved alternate products like AVM System 700 must be used.

For the official ordinance and latest updates, check your city or county planning department.

Frequently asked questions about ADU regulations in Los Alamitos

• What is the maximum ADU size in Los Alamitos, California?

  In Los Alamitos, the maximum ADU size is typically NaN square feet, depending on whether the unit is attached or detached. California state law allows up to 1,200 sq ft for detached ADUs and 800 sq ft for attached in many jurisdictions; Los Alamitos may follow state defaults or have local limits. Verify with Los Alamitos planning for your specific lot.

• What are the setback requirements for ADUs in Los Alamitos?

  In Los Alamitos, typical setback requirements are 4 feet from the side property line and 4 feet from the rear. These may be reduced to 4 feet under California Government Code § 65852.2 where applicable. Check with Los Alamitos planning for overlay zones or design standards that could affect your site.

• What is the maximum height for an ADU in Los Alamitos?

  In Los Alamitos, the maximum height for an ADU is generally 16 feet. State law often allows up to 16 feet for detached ADUs and up to 25 feet when within 4 feet of the property line in some cases. Confirm with Los Alamitos or county planning for your zone.

• Is ADU approval ministerial in Los Alamitos?

  In Los Alamitos, ADU approval is typically Ministerial (by-right) per Gov Code §65852.2. Ministerial (by-right) review means the city must approve qualifying applications without discretionary review, per California Gov Code § 65852.2. Your project must still meet objective standards; Los Alamitos planning can confirm the exact process.

• Are there parking requirements for ADUs in Los Alamitos?

  In Los Alamitos, parking for ADUs is generally Often waived per state law; check local ordinance. California law often waives parking for ADUs within a half-mile of transit or in certain historic districts. Check with Los Alamitos planning for your address.