ADU Regulations in San Luis Obispo County, California (2026)
Summary from local ordinance data. Verify with city planning for your specific lot.
Regulations at a glance
| Rule | Value |
|---|---|
| Max ADU Size | 1000 sq ft |
| Side Setback | 4 ft |
| Rear Setback | 4 ft |
| Max Height | 16 ft |
| Approval Type | Ministerial (by-right) per Gov Code §65852.2 |
| Parking Requirements | false |
Local rules & notes
Lot Coverage Exclusion: A significant incentive where the first 800 square feet of an ADU is not counted toward the property's maximum lot coverage ratio. Director's Size Exception: The Director has discretionary authority to increase the maximum allowable size of an ADU to 1,200 square feet. Guest Quarters Conversion: Specific provisions allow for the conversion of legally established guest quarters into ADUs, though only one ADU or guest quarter is allowed per property.
For the official ordinance and latest updates, check your city or county planning department.
Frequently asked questions about ADU regulations in San Luis Obispo County
What is the maximum ADU size in San Luis Obispo County, California?
In San Luis Obispo County, 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; San Luis Obispo County may follow state defaults or have local limits. Verify with San Luis Obispo County planning for your specific lot.
What are the setback requirements for ADUs in San Luis Obispo County?
In San Luis Obispo County, 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 San Luis Obispo County planning for overlay zones or design standards that could affect your site.
What is the maximum height for an ADU in San Luis Obispo County?
In San Luis Obispo 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 San Luis Obispo County or county planning for your zone.
Is ADU approval ministerial in San Luis Obispo County?
In San Luis Obispo 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; San Luis Obispo County planning can confirm the exact process.
Are there parking requirements for ADUs in San Luis Obispo County?
In San Luis Obispo County, 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 San Luis Obispo County planning for your address.
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