How Sunnyvale Handles Accessory Structures: A Practical Guide
Sunnyvale maintains 125 local ordinances across all categories, and 9 of those deal specifically with accessory structures. Here is a breakdown of what the city actually requires, what is prohibited, and where Sunnyvale falls on the strict-to-permissive spectrum compared to other cities.
Tiny Homes
Tiny homes on foundations qualify as ADUs in Sunnyvale under state law. Tiny homes on wheels are regulated as RVs and cannot be used as permanent dwellings outside of RV parks or approved JADU setups.
Key details: Foundation tiny home: Treated as ADU. Minimum size: 150 square feet. Tiny home on wheels: Regulated as RV. RV as dwelling: Prohibited on residential lots. State law: HSC 18009.3 and ADU statute.
Contact your local code enforcement office for specific penalty information.
Carport Rules
Carports are permitted in Sunnyvale as accessory structures under Municipal Code Chapter 19.38. Residential carports must meet zoning setbacks, height limits, and building permit requirements when over 120 square feet.
Key details: Code reference: SMC Chapter 19.38. Side setback R-1: 5 feet typical. Permit threshold: Over 120 square feet. Front yard: Usually not allowed. Counts as covered parking: Yes.
Contact your local code enforcement office for specific penalty information.
ADU Owner Occupancy
Under SMC Title 19 and California Government Code 65852.2(a)(8), Sunnyvale does NOT require owner-occupancy for standard ADUs. Owner-occupancy is required only for Junior ADUs (JADUs) under California Government Code 65852.22, with a deed restriction recorded against the property.
Key details: Standard ADU: No owner-occupancy required. JADU Rule: Owner must live in primary OR JADU. State Authority: Gov. Code 65852.2(a)(8); 65852.22. JADU Deed Restriction: Recorded with Santa Clara County. AB 1033 Separate Sale: Not yet adopted.
Failing to record the JADU deed restriction blocks issuance of the Certificate of Occupancy. Violating the JADU owner-occupancy requirement is enforced through deed-restriction enforcement and code-compliance citations under SMC 1.04 starting at $100. The city can also seek injunctive relief and revocation of the Certificate of Occupancy.
The rules around adu owner occupancy in Sunnyvale lean permissive, but that does not mean anything goes.
ADU Impact Fees
Under California Government Code 65852.2(f)(3), Sunnyvale ADUs under 750 square feet are exempt from all city impact fees. ADUs 750 square feet or larger pay impact fees proportional to the primary dwelling. Sunnyvale's own permit and plan-check fees are moderate by Silicon Valley standards.
Key details: Authority: Gov. Code 65852.2(f)(3). Sub-750 sq ft ADU: Exempt from all city impact fees. 750+ sq ft ADU: Proportional impact fees. Permit/Plan Check: ~$3,000-$6,000 (any size). School Fees Authority: Ed. Code 17620 (~$5.17/sq ft).
Sunnyvale cannot legally charge impact fees on a sub-750 sq ft ADU. If fees are charged in error, the homeowner may request a refund through Finance or sue under California Code of Civil Procedure 1085. The Mitigation Fee Act (Gov. Code 66020) allows protest of impact fees within 90 days of payment.
Sunnyvale is more permissive than most cities when it comes to adu impact fees. That said, there are still limits.
ADU Rental Restrictions
Sunnyvale prohibits short-term rentals of ADUs - stays must be 30 days or longer under California Government Code 65852.2(a)(6) and SMC Title 19. Long-term ADU rentals are not subject to local rent control (Sunnyvale has no rent stabilization ordinance) but are subject to statewide AB 1482 just-cause and rent-cap protections.
Key details: Minimum Stay: 30 days (Gov. Code 65852.2(a)(6)). Short-Term Rental: Not allowed for ADUs. Rent Control: None in Sunnyvale. AB 1482: Applies (5%+CPI, just cause). SFH/ADU Exemption: AB 1482 with proper notice.
Operating an ADU as an STR violates SMC Title 19 and Gov. Code 65852.2(a)(6). Code Enforcement issues citations under SMC 1.04 starting at $100, escalating to $200 and $500 per violation; the city actively monitors Airbnb/Vrbo for Sunnyvale listings. AB 1482 violations (illegal rent increases or no-cause evictions) expose landlords to tenant damages of actual harm plus up to 3x rent and attorney fees under Civ. Code 1947.12(j).
ADU Permits
Sunnyvale processes ADU permits ministerially under Sunnyvale Municipal Code Title 19 (Zoning) and California Government Code 65852.2. Sunnyvale was one of the earliest California cities to adopt by-right ADU regulations (2017) and consistently rates as one of the most permissive Silicon Valley jurisdictions. State law requires action within 60 days of a complete application.
Key details: Code Section: SMC Title 19 (Zoning). Review Type: Ministerial (no hearing). Decision Window: 60 days from complete app. Allowed Units: 1 ADU + 1 JADU per SFH lot. Early Adopter: 2017 by-right rules.
Building an ADU without a permit violates SMC Title 16 (Building) and Title 19 (Zoning). Sunnyvale Code Enforcement can issue stop-work orders, administrative citations starting at $100 per violation (SMC 1.04), double permit fees on legalization, and orders to remove unpermitted structures. Unpermitted ADUs commonly block sale and refinancing of the property.
The rules around adu permits in Sunnyvale lean permissive, but that does not mean anything goes.
Shed Rules
Sunnyvale allows backyard sheds up to 120 square feet without a building permit under Municipal Code Chapter 19.38. Sheds must meet setbacks and cannot be used as living space or connected to utilities.
Key details: Permit-free size: Up to 120 square feet. Side setback: 3 feet typical. Height limit: 10 feet. Utilities: No permanent hookups without permit. Habitable use: Prohibited.
Contact your local code enforcement office for specific penalty information.
If you are coming from a city with tighter rules, you will find Sunnyvale gives residents more flexibility on shed rules.
Garage Conversions
Sunnyvale allows garage conversions to ADUs or JADUs under state law. Detached garage ADUs are ministerial. Replacement parking is no longer required under California AB 68 and updated ADU rules.
Key details: Ministerial approval: Yes under state law. Replacement parking: Not required. JADU max: 500 square feet. Expansion allowance: 150 sq ft for egress. Permit required: Yes, building permit.
Contact your local code enforcement office for specific penalty information.
Sunnyvale is more permissive than most cities when it comes to garage conversions. That said, there are still limits.
ADU Rules
Sunnyvale allows ADUs and JADUs on single-family and multifamily lots under California Government Code 65852.2 plus AB 68, 881, and SB 13. AB 1033 now allows ADUs to be sold as separate condos.
Key details: State law: Gov Code 65852.2 plus AB 68, 881, SB 13. Max detached ADU: 1200 square feet. JADU size: Up to 500 square feet. Setbacks: 4 feet side and rear. AB 1033: Condo sale if city opts in.
Contact your local code enforcement office for specific penalty information.
The rules around adu rules in Sunnyvale lean permissive, but that does not mean anything goes.
The Bottom Line
Compared to many U.S. cities, Sunnyvale gives residents more room on accessory structures. 6 of the 9 rules here are rated permissive. But permissive does not mean unregulated. There are still requirements, and the city does enforce them when violations are reported.
All of the above reflects Sunnyvale's municipal code as of our last review. If you need specifics on fines, exemptions, or filing requirements, the detailed ordinance pages linked above have the full breakdown.