How to Get an ADU Permit in Sunnyvale

Why Build an ADU in Sunnyvale?

As housing costs soar across the Bay Area, homeowners in Sunnyvale are increasingly turning to Accessory Dwelling Units (ADUs) as a way to expand livable space, create passive income, and boost long-term property value. Sunnyvale supports ADU construction through local ordinances that align with California’s state laws, making it easier than ever to legally build or convert a structure into an ADU.

What Is an ADU?

An Accessory Dwelling Unit (ADU) is a self-contained residential unit located on the same property as a primary home. In Sunnyvale, ADUs can take multiple forms:

Detached ADUs (backyard cottages)
Attached ADUs (built onto the main house)
Garage conversions
Junior ADUs (JADUs) — smaller units under 500 sq. ft., usually built within the main home

Sunnyvale ADU Zoning & Building Requirements (2025)

Sunnyvale follows California state laws (like SB 9, SB 13, AB 68) and also applies local standards that are favorable to homeowners.

Requirement	Standard
Zoning	Allowed on all R-1 (Single-Family) and R-2 lots
Max Size	Up to 1,200 sq. ft. for detached units
Height Limits	16 ft. (detached), up to 25 ft. for some attached ADUs
Setbacks	4 ft. side and rear setbacks
Parking	Not required if within ½ mile of public transit
Garage Conversions	Fully legal, no extra parking required
Fire Sprinklers	Not required if not needed for primary residence

Step-by-Step Guide: How to Get an ADU Permit in Sunnyvale

1. Determine Eligibility

Check if your property is:

Zoned R-1 or R-2
Has an existing primary residence
Has room for required setbacks and access

2. Choose Your ADU Type

Decide on the best fit for your needs:

Garage conversion (lowest cost, fastest approval)
Detached backyard unit (more privacy)
Attached addition (connects to primary home)
Junior ADU (minimal upgrades inside the existing home)

3. Hire an ADU Designer or Architect

Your plans must comply with:

California Building Code
Energy Code (Title 24)
Accessibility standards (if required)
Fire safety and egress

A professional designer can prepare:

Site plan
Floor plan
Elevations
Structural calculations
Title 24 documentation

4. Submit Permit Application

Submit your plans and application to the Sunnyvale Building Division. You may need:

ADU application form
Architectural drawings
Site plan with measurements
Title 24 report
Owner’s affidavit
Application fee payment

Sunnyvale offers electronic plan submission via its online portal.

5. City Plan Review (60-Day Timeline)

By California law, your application must be reviewed within 60 days. The City will:

Review zoning and building compliance
Request corrections (if needed)
Approve or conditionally approve the permit

6. Pay Permit Fees

Estimated Costs:

Fee Type	Estimated Cost
Building Permit	$1,500 – $4,000
Plan Review Fee	$1,000 – $2,500
School Impact Fees	~$3.50 per sq. ft. (over 500 sq. ft.)
Sewer/Utility Connection	May vary depending on scope
Total (typical range)	$3,500 – $12,000+

7. Begin Construction & Schedule Inspections

After the permit is issued, your contractor can begin building. Be sure to schedule:

Foundation inspection
Framing & rough plumbing
Insulation inspection
Final walk-through

8. Final Approval & Certificate of Occupancy

Once inspections are complete and compliant, Sunnyvale will issue a Certificate of Occupancy—your ADU is now legally habitable and rentable.

Benefits of Building an ADU in Sunnyvale

✅ Affordable housing solution for aging parents, adult children, or renters
✅ Rental income potential in a high-demand market
✅ Increases property value without requiring lot subdivision
✅ Flexible design options: Convert your garage or build a custom unit
✅ Complies with state mandates to expedite ADU development

Common Mistakes to Avoid

❌ Submitting incomplete plans
❌ Assuming old garages are code-compliant
❌ Not factoring in energy compliance costs
❌ Overlooking utility connection fees
❌ Hiring unlicensed contractors

FAQ

How long does it take to get an ADU permit in Sunnyvale?

By law, the city must approve or deny a complete application within 60 days.

Can I convert my garage into an ADU in Sunnyvale?

Yes. Detached garage conversions are legal in Bakersfield if the structure is sound and meets current code.

Are ADUs allowed on duplex or multi-family lots?e address or utility hookup?

Yes. You can build multiple ADUs, depending on the lot size and existing structures.

Do I need fire sprinklers in my ADU?

Only if they are required for the main home or if the ADU exceeds a certain size (check with the building department).

Do I need separate utilities for the ADU?

No, but separate connections are optional and may be required in some cases depending on your design.