ADU Jurisdiction Guide: City of Hayward
Fees and Regulations (August 2022)

ADU-allowed Zones

Having ADU on your property is allowed as long as your lot is zoned for residential use (exceptions may vary) and as long as you have an existing single-family home or a multi-family building. 

Single-unit dwelling:
– One (1) ADU – within the existing space of the property 
– One (1) JADU per lot

Multiple-unit dwelling:
– 25% of existing units or one (1) unit, whichever is greater
– Two (2) detached ADUs

ADU Size Limitations

A local government may, by ordinance, establish minimum and maximum unit size requirements for both attached and detached ADUs. 

However, maximum unit size requirements with one bedroom must be at least 850 square feet and 1,000 square feet for ADUs with more than one bedroom. 

If ADU exceeds the thresholds above, ADUs shall not exceed 50% of the total floor area of the primary dwelling or 1,200 square feet whichever is less

ADU Building Height

16 feet. Per the Building Code, the detached ADU height limit allows for a maximum of 2 floors. ADUs attached to primary structures shall not exceed the height allowed by the underlying zoning district. No limit for conversions within existing, permitted structures.

Minimum Lot Size

No minimum. ADUs greater than 800 square feet are required to provide the minimum open space requirements of the underlying zoning district of the project site.

Maximum Lot Size

The ADU shall not exceed the maximum lot coverage of the underlying zoning district of the project site; however, lot coverage shall not be imposed for attached or detached ADUs less than 800 square-feet.

Setbacks Requirements

  • Front: 20ft
  • Side: 4 feet
  • Rear 4 feet
  • Distance between structures: 6 feet

Parking Space Requirements

  • Attached and detached ADUs will require 1 parking space unless your project qualifies for an exemption from the parking requirements.
    • ½ Mile from Public Transport

Owner Occupancy Requirements


Other Regulations

  • ADUs shall be required to have fire sprinklers if either of the following conditions exist.  1) The existing units have fire sprinklers.  2) There are any active improvements or additions that would require the existing units
  • ADUs require a 1-hour fire-rated wall that extends from the bottom of the footing to the underside of the roof deck to fully separate the existing multi-family dwelling from the repurposed ADU. If the ADU is a conversion under habitable space of the existing multi-family dwelling, the 1-hour fire rating also applies to the floor/ceiling assembly between the units.
  • The City of Hayward has a local green building regulation called the Reach Code. This ordinance prohibits the use of natural gas in newly constructed detached ADUs that are over 400 square feet. This means that water heaters and space conditioning shall utilize heat pumps and cooking appliances shall be all-electric.
  • ADUs shall not be utilized as commercial short-term rentals (i.e. rentals less than 30 days).  
  • All ADUs shall have their own independent address. 
  • Park impact and school district fees are applicable for ADUs that are equal to or greater than 750 square feet. Affordable housing fees are applicable for ADUs that are equal to or greater than 750 square feet if the project involves two or more new units.

ADU Permit Fees

Building Inspection Fees
– $150,000 Valuation for Maverick 392: $1,613.65
– $174,000 Valuation for Maverick 504: $1,783.66
– $200,000 Valuation for Maverick 748: $1,968.15

Fire Inspection Fee: $221

Haz-Mat Inspection Fee: $330 per inspection

Planning/Landscape Inspection Fee: $212

Planning Review Fee: $564 – $688 (may vary according to valuation)

Fire Review Fee: $564 – $688 (may vary according to valuation)

Administrative Fee: $432.98


We hope this quick reference guide helps you out in your ADU project. Part of our service if you build with us is the full service of our in-house permit technician who handle the processing of your permit on your behalf with no mark-ups. 

If you’re interested in building with ADU.Works, please don’t hesitate to book a consultation with us or give us a quick call through our number +1 (650) 227 4810. We’ll gladly discuss the specifications of your permit processing and accommodate any questions you may have. Our team looks forward to hearing from you.

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