ADU Regulations in Belmont, California (2026)

Regulations at a glance

Local rules & notes

Reverse Corner Lot Setbacks: The City attempts to enforce stricter setbacks on reverse corner lots, requiring the ADU not to project beyond the front yard of the adjacent rear lot. HCD declares this invalid as state law caps setbacks at 4 feet. Subjective Design Standards: The City imposes subjective design requirements such as 'compatible façade materials' and 'same color palette'. HCD requires all standards to be objective and verifiable without personal judgment. Distance Between Buildings: The City requires a 5-foot separation between the primary dwelling and detached ADU. HCD states this cannot be applied to statewide exemption ADUs. Multifamily Unit Caps: The City restricts multifamily lots to 1 interior and 2 detached ADUs. HCD clarifies that state law allows up to 25% of existing units as interior ADUs and up to 2 detached (or 8 on existing lots).

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

Frequently asked questions about ADU regulations in Belmont

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

  In Belmont, 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; Belmont may follow state defaults or have local limits. Verify with Belmont planning for your specific lot.

• What are the setback requirements for ADUs in Belmont?

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

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

  In Belmont, 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 Belmont or county planning for your zone.

• Is ADU approval ministerial in Belmont?

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

• Are there parking requirements for ADUs in Belmont?

  In Belmont, 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 Belmont planning for your address.