Alameda County

Hayward ADU rules

Research summary of local ADU rules on file for Hayward in Alameda County. Not a determination for a specific lot.

Last checked October 23, 2026.

City or county ADU page

Hayward rules on file

Local rules recorded in this project for this jurisdiction. Where a city figure on file is stricter than the state baseline on file, both are shown.

How to apply
All ADU and JADU permits are submitted through the Hayward e-Permit Portal, and you need a registered portal account first. Choose “Residential - Accessory Dwelling Unit (ADU)” for a custom design, or “Residential - Accessory Dwelling Unit (ADU) - Using Pre-Approved ADU Plans” for a plan from the City's ADU Plans Gallery.
Source: City of Hayward, ADU and JADU page (updated June 9, 2026), Submitting an Application, accessed 2026-10-23.

Talk to a planner first
The City asks you to contact a planner, by email or at (510) 583-4216, with the project address and a description of the project to confirm the site can have an ADU and which submittal materials apply.
Source: City of Hayward, ADU and JADU page (updated June 9, 2026), Submitting an Application, accessed 2026-10-23.

What a custom ADU submittal includes
Construction documents (site plan, floor plan, existing and proposed elevations, sections, details and a Title 24 energy report) on 18 x 24 or 24 x 36 inch sheets, all the same size; the City's ADU checklist for your project type (single-family ADU, single-family JADU or multifamily ADU); and an owner authorization form if the applicant is not the owner.
Source: City of Hayward, ADU and JADU page (updated June 9, 2026), Required Submittal Materials: Custom ADU/JADU, accessed 2026-10-23.

Extra item for some junior ADUs
A copy of the property's legal description (from the title report or grant deed) is required only for junior ADUs that share sanitation facilities with the main home.
Source: City of Hayward, ADU and JADU page (updated June 9, 2026), Required Submittal Materials: Property Legal Description, accessed 2026-10-23.

Using a plan from the City's ADU Plans Gallery
Upload the plan set bought from a designer listed in the Hayward ADU Plans Gallery, plus a site-specific site plan and foundation details and the ADU checklist.
Source: City of Hayward, ADU and JADU page (updated June 9, 2026), Required Submittal Materials: “Pre-Approved” ADU, accessed 2026-10-23.

When fees are paid
A plan review fee is due before review starts. Other permit fees are due when the permits are ready to issue. The City's Permit Center Fee Estimator lists specific development fees.
Source: City of Hayward, ADU and JADU page (updated June 9, 2026), Paying Fees, accessed 2026-10-23.

California state rules on file

The statewide baseline recorded from state law and the HCD ADU Handbook.

Detached size cap described in state law
1,200 sq ft. Recorded in this rules file from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Side and rear setback cap for a new ADU
4 ft. Recorded in this rules file from Government Code section 66314, which describes a cap on side and rear setbacks for a new ADU.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Setback for a conversion of an existing structure
No additional setback, as recorded in this rules file from Government Code section 66314 for a conversion of an existing structure.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Minimum lot size
A city may not impose a minimum lot size for an ADU, as recorded in this rules file from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Minimum unit the handbook says cities must allow
At least an 800 sq ft ADU with 4 ft side and rear setbacks. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(3).
Source: HCD ADU Handbook, 66321(b)(3); handbook updated March 2026, accessed 2026-10-16.

Detached height described in the handbook
16 ft, or 18 ft or 20 ft in some cases. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(4).
Source: HCD ADU Handbook, 66321(b)(4); handbook updated March 2026, accessed 2026-10-16.

Permit decision deadline
60 days. Recorded in this rules file from Government Code section 66317(a)(3): the permitting agency must decide on (approve or deny) a completed ADU application within 60 days when an existing single-family or multifamily dwelling is on the lot. Section 66317(a)(1) says the application is considered ministerially, without discretionary review or a hearing.
Source: California Government Code section 66317, 66317(a)(1), (a)(3), accessed 2026-10-17.

Owner-occupancy requirement
None. Recorded in this rules file from Government Code section 66315: a local agency may not impose an owner-occupancy requirement on an ADU. It may require that the property be used for rentals of terms 30 days or longer. The HCD ADU Handbook (updated March 2026) describes the same rule.
Source: California Government Code section 66315, 66315; HCD ADU Handbook updated March 2026, accessed 2026-10-17.

Parking near public transit
No parking standards within one-half mile walking distance of public transit. Recorded in this rules file from Government Code section 66322(a)(1). Section 66322(a) lists several other cases where parking standards may not be imposed.
Source: California Government Code section 66322, 66322(a), accessed 2026-10-17.

Ministerial categories
The HCD ADU Handbook (updated March 2026) states that Government Code section 66323 sets four ministerial categories. This rules file does not restate those four categories.
Source: HCD ADU Handbook, 66323; handbook updated March 2026, accessed 2026-10-16.

Fire Hazard Severity Zones
If your lot is in a Fire Hazard Severity Zone, the CAL FIRE Office of the State Fire Marshal says in Information Bulletin 25-004 (issued March 3, 2025): “Fire Hazard Severity Zones (FHSZs) should not restrict the development of Accessory Dwelling Units (ADUs). However, additional building standards may be necessary, including but not limited to California Fire Code Chapter 49 and California Building Code Chapter 7A.” State ADU law does not itself bar an ADU there. A city or county may still apply its building code, including wildfire-resistant construction (Gov. Code 66314(d)(8)); require side and rear setbacks “sufficient for fire and safety” for a unit converted under 66323(a)(1); and decline parking in setbacks on specific fire and life safety findings (66314(d)(10)(B)). It may also consider public safety when it designates where ADUs may be permitted (66314(a)). Sprinklers can't be required in an ADU or JADU if the primary residence doesn't need them (66314(d)(12), 66323(d)). Some cities and counties still apply their own fire-zone limits. Where this summary has one, it is listed with the local rules. This summary does not look up your lot. Check the CAL FIRE Fire Hazard Severity Zone map viewer linked from the State Fire Marshal's Fire Hazard Severity Zones page: https://experience.arcgis.com/experience/5065c998b4b0462f9ec3c6c226c610a9
Source: CAL FIRE Office of the State Fire Marshal Information Bulletin 25-004, page 4, issued March 3, 2025; Gov. Code 66314, 66323, accessed 2026-10-20.

State baseline on the directory → · State ADU rules on the homepage →

Can I build an ADU in Hayward?

State law sets a baseline for ADUs in Hayward, and the local standards on file are listed on this page. Whether a specific lot can add an ADU depends on zoning, utilities, and other site facts this page does not measure. Confirm with City of Hayward Planning Division, or run a free address summary.

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