ADU Regulations in Imperial County, California (2026)

Regulations at a glance

Local rules & notes

Minimum Lot Size Restriction: The ordinance imposes a minimum lot size of 9,000 sq ft in R-1 zones and 20,000 sq ft in Agricultural zones to permit an ADU, which is highly restrictive. Primary Dwelling Minimum Size: An ADU is not allowed unless the principal dwelling on the lot contains a minimum gross area of at least 1,000 square feet. Detached ADU Size Limit (Percentage): The ordinance applies a 50% size limit (relative to primary residence) to all second residential units, including detached ones, which contradicts the standard 1,200 sq ft allowance.

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

Frequently asked questions about ADU regulations in Imperial County

• What is the maximum ADU size in Imperial County, California?

  In Imperial County, the maximum ADU size is typically 1200 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; Imperial County may follow state defaults or have local limits. Verify with Imperial County planning for your specific lot.

• What are the setback requirements for ADUs in Imperial County?

  In Imperial County, typical setback requirements are 5 feet from the side property line and 5 feet from the rear. These may be reduced to 4 feet under California Government Code § 65852.2 where applicable. Check with Imperial County planning for overlay zones or design standards that could affect your site.

• What is the maximum height for an ADU in Imperial County?

  In Imperial County, 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 Imperial County or county planning for your zone.

• Is ADU approval ministerial in Imperial County?

  In Imperial County, 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; Imperial County planning can confirm the exact process.

• Are there parking requirements for ADUs in Imperial County?

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