ADU Regulations in Alpine County, California (2026)

Regulations at a glance

Local rules & notes

Future Date / Pending Vote: The document is dated 'REVISED FURTHER 16 MARCH 2025' and marked 'PENDING VOTE', indicating it is a draft or future-effective document. Strict Parking Requirements: Requires 2 parking spaces for ADUs with 2 or more bedrooms, which exceeds the typical state default of 1 space per unit/bedroom. Detached ADU Size Cap (40% Rule): Applies a 40% of primary residence floor area cap to detached ADUs. State law typically only applies percentage caps to attached ADUs. Large Lot Size Bonus: Allows ADUs up to 1,500 sq ft on lots larger than 2.0 acres, which is larger than the standard 1,200 sq ft state maximum.

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

Frequently asked questions about ADU regulations in Alpine County

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

  In Alpine County, the maximum ADU size is typically 1500 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; Alpine County may follow state defaults or have local limits. Verify with Alpine County planning for your specific lot.

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

  In Alpine 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 Alpine County planning for overlay zones or design standards that could affect your site.

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

  In Alpine 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 Alpine County or county planning for your zone.

• Is ADU approval ministerial in Alpine County?

  In Alpine 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; Alpine County planning can confirm the exact process.

• Are there parking requirements for ADUs in Alpine County?

  In Alpine 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 Alpine County planning for your address.