ADU Regulations in Fontana, California (2026)

Regulations at a glance

Local rules & notes

Hillside Overlay District (HOD) Fire Restrictions: Due to high fire risk, ADUs in the HOD are limited to 800 sq ft and require an 8-foot building separation (reducible to 5 ft if necessary for an 800 sq ft unit). Front Setback Encroachment: ADUs are permitted in the front setback if adhering to the setback would preclude an 800 sq ft unit. Nonprofit Separate Sale: ADUs developed by a qualified nonprofit corporation may be sold or conveyed separately from the main building to a qualified buyer.

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

Frequently asked questions about ADU regulations in Fontana

• What is the maximum ADU size in Fontana, California?

  In Fontana, the maximum ADU size is typically 1000 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; Fontana may follow state defaults or have local limits. Verify with Fontana planning for your specific lot.

• What are the setback requirements for ADUs in Fontana?

  In Fontana, 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 Fontana planning for overlay zones or design standards that could affect your site.

• What is the maximum height for an ADU in Fontana?

  In Fontana, the maximum height for an ADU is generally 25 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 Fontana or county planning for your zone.

• Is ADU approval ministerial in Fontana?

  In Fontana, 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; Fontana planning can confirm the exact process.

• Are there parking requirements for ADUs in Fontana?

  In Fontana, parking for ADUs is generally false. California law often waives parking for ADUs within a half-mile of transit or in certain historic districts. Check with Fontana planning for your address.