Hayward | ADUs and SB 9
Hayward ADUs, Junior ADUs and SB 9 Two-Unit Projects
An accessory dwelling unit (ADU) is a second, smaller home on a lot with a house or apartment building, with its own kitchen, bathroom and sleeping area. A junior ADU is a unit of 500 square feet or less inside a house. SB 9 is the 2021 state law that lets an owner build two main homes on a single-family lot. Hayward's code has one ADU sentence and one SB 9 row in its use table, both pointing to state law, and City checklists set the details. This page reads the checklists against the statutes. See the Hayward overview for the whole guide.
Hayward ADUs and SB 9 in six facts
- The Hayward ADU section, 10-1.2741, refers to state law for ADU rules and sets no City standards of its own. Source: HMC 10-1.2741
- The City checklist allows a new detached ADU of up to 1,200 square feet of interior livable space, 16 feet tall, or 18 feet near major transit. Source: Hayward SFR ADU Checklist
- State law requires a decision on a complete ADU application within 60 days when a home already exists on the lot. Source: Gov. Code 66317
- No impact fee may be charged on an ADU of 750 square feet of interior livable space or less. Source: Gov. Code 66311.5
- A two-unit SB 9 development is permitted only in the RL district, with 4 foot side and rear setbacks and a 30 foot height limit. Source: HMC 10-1.202; SB 9 checklist
- The City deposit for an SB 9 application is $4,000 without a tentative map and $6,000 with one. Source: FY 2026-27 Master Fee Schedule
Hayward Applies State ADU Law Directly
Hayward added ADU sections in 2017; the code's note says "Ordinance 17-16, adopted November 7, 2017, adding Sections 10-1.2740 through 10-1.2747." Ordinance 24-01 of January 23, 2024 cut them back to one sentence. Section 10-1.2741 now reads: "This Section provides reference to the regulations for Accessory Dwelling Units provided in Government Code Sections 65852.2 and 65852.22, as amended from time to time." Sections 10-1.2742 to 10-1.2747 are "Reserved."
Those two Government Code numbers are out of date. The state ADU rules now sit in Government Code 66314 and the sections after it, added by SB 477 in 2024, and the current law table in the Legislature's database has no Section 65852.2 or 65852.22. The City's own ADU checklist uses the new numbers: ADUs are allowed "pursuant to State law" in "Government Code Sections 66314 through 66332." Read the code's reference as a pointer to the current state sections.
The use tables permit ADUs in every residential district, and Table 10-1.802 permits them in all six commercial districts, "Where primary use is residential." The City's ADU page, updated June 9, 2026, says every ADU and junior ADU permit goes through the Hayward e-Permit Portal and "All projects are reviewed for compliance with applicable California State Codes and California State Law." Owners can use a custom design or a pre-approved plan set bought from a designer in "Hayward's ADU Plans Gallery," and add a site plan and site-specific foundation details.
ADU Sizes, Heights and Setbacks
| Type | Size | Height | Setbacks |
|---|---|---|---|
| Converted ADU (inside existing space) | No size limit in the checklist; state law allows 150 sq ft added for entry | Within existing space | None for existing permitted structures |
| Detached new ADU | Up to 1,200 sq ft interior livable space (checklist); at least 800 sq ft must be allowed | 16 ft, or 18 ft within one-half mile of a major transit stop | 4 ft side and rear; front by the zone; 5 ft from other structures |
| Attached ADU | 50% of the main home (checklist); the state floor is 850 or 1,000 sq ft | Zone height limit (checklist); state law: 25 ft or the zone limit, whichever is lower | 4 ft side and rear |
| Junior ADU | No larger than 500 sq ft inside the home | Inside the home | Inside the home |
Source: City of Hayward Single-Family Residential ADU Checklist, updated April 2026; Government Code 66321 and 66323.
The checklist says a project that answers yes or not applicable to every question "is eligible for ministerial ADU review by staff," a review against fixed rules with no hearing. Newly built ADUs must keep 4 feet from side and rear lines, follow the zone's front yard, and stay 5 feet from other structures. The checklist sets no size limit for an ADU converted from an existing, permitted structure. Height is measured "from grade to the highest point of the roof for flat roof" and to the midpoint of the highest gable for a pitched roof.
Building rules come with the checklist too. An attached ADU needs a 1-hour fire rated wall from "the bottom of the footing to the underside of the roof deck," and no door may connect it to the main house. Fire sprinklers are required only if the main house has them or other work on the house would require them. The ADU needs its own heat source, may share a water heater that is sized for both units, and may drain through the main house's sewer line.
The zoning code adds one spacing rule. Section 10-1.204(n) says detached homes on one lot must be "setback at least 10 feet from each other," and "The separation for ADUs may be reduced to 5 feet." Accessory buildings other than ADUs are capped at 14 feet and one story in Table 10-1.203; ADUs follow the checklist heights.
Process, Fees and Utilities
- Deadlines. Government Code 66317 requires the City to say whether an application is complete within 15 business days, and to approve or deny it "within 60 days" of a complete application when a home already exists on the lot. If it does not act, "the application shall be deemed approved."
- Fee timing. The ADU page says "A Plan Review Fee is due prior to project review. All other permits fees are due when the permits are ready for issuance."
- Zoning fee. The FY 2026-27 fee schedule lists a Zoning Conformance Permit for ADUs at $498 and a housing plan review fee of $158 for ADUs.
- Park and school fees. The fee schedule lists a $3,379 park impact fee for an "ADU that is 750+ s.f." The checklist says park and school fees apply to ADUs that are "equal or" greater than 750 square feet.
- Traffic fee. Section 10-30.15(h) says "No fee is applicable for remodeling, adding to an existing unit, or adding an accessory dwelling unit (ADU)."
- Sewer. The fee schedule lists the sewer connection charge for an ADU at $5,825 each from September 1, 2026, "where applicable." The checklist says utility charges "apply to all ADUs."
- Address. "All ADUs shall have their own independent address," at $340 each under the fee schedule.
- Rentals. The checklist bars commercial short-term rentals of less than 30 days. State law in Government Code 66315 bars an owner-occupancy rule for ADUs.
Junior ADUs follow Government Code 66333: one per lot, inside the walls of the house, with a separate entrance and a recorded deed restriction against selling it apart from the house. The owner must live on the property if the junior ADU shares a bathroom with the house. The City asks for the property legal description "Only required for JADUs that share sanitation facilities with the primary residence," which is the case that triggers that rule.
SB 9 Two-Unit Projects in RL
| Topic | Rule |
|---|---|
| Where | RL district only |
| Homes | Two units; with a lot split, two units per lot, counting ADUs |
| Setbacks | 4 ft interior side and rear; 15 ft front, or 20 ft for an attached garage; 10 ft street side; 5 ft from other buildings |
| Height and design | 30 ft; second floor massing under 10-1.205(a); 50 facade design points |
| Parking | 1 space per unit, none within one-half mile walking distance of a major transit stop or high-quality transit corridor, or near car share |
| Size floor | Standards give way if they would prevent two 800 sq ft units |
| Rentals | No short-term rentals of less than 30 days |
Source: Hayward Municipal Code Table 10-1.202; City of Hayward SB 9 Eligibility and Checklist, updated March 2025; Government Code 65852.21.
Table 10-1.202 lists "Two-Unit Development" as permitted in RL only, "As provided in Government Code Sections 66411.7 and 65852.21." The City has no SB 9 ordinance; its SB 9 checklist lists the "eligibility requirements and objective development standards for ministerial approval." The objective standards apply "unless the standards below preclude the development of two (2) 800 square-foot units" on the property, which repeats the size floor in Government Code 65852.21.
The design rules come from the RL district. New SB 9 homes must meet the second story massing rule in Section 10-1.205(a), which caps a second floor at 80 percent of the first floor on a house of 3,000 square feet or less, and must earn 50 facade design points from Table 10-1.205.1, such as 30 points for a covered porch at each entry or 20 for windows covering 20 percent of the front. Height is 30 feet.
The checklist screens the site. The project may not demolish or alter rent-restricted housing, housing under "any form of rent or price control," housing taken off the rental market under the Ellis Act in the past 15 years, or housing "occupied by a tenant in the last three years." Hayward's rent ordinance covers many older rentals, so check the City's rent review database, which the checklist links. Sites on prime farmland, wetlands, conservation land or protected habitat are barred. Sites in a very high fire zone, a hazardous waste site, an earthquake fault zone, a FEMA flood zone or a floodway must meet added conditions, such as "a no-rise certificate" for a floodway.
With a lot split, the checklist limits each parcel to two housing units, and "an Accessory Dwelling Unit is considered a housing unit." Without a split, a lot may hold the two SB 9 homes plus ADUs. The lots and subdivisions page covers the split itself.
Where City Documents and State Law Differ
- ADU count. The checklist says a house lot is "limited to one" detached or attached ADU and one junior ADU. Government Code 66323(a) requires approval of "any combination" of a converted ADU and junior ADU inside existing space plus one new detached ADU of up to 800 square feet. The statute controls.
- Attached ADU size. The checklist caps an attached ADU at 50 percent of the main home. Government Code 66321 bars a maximum below 850 square feet, or 1,000 for more than one bedroom, and any rule that blocks an 800 square foot ADU with 4 foot setbacks.
- The 750 square foot line. The checklist and the "750+ s.f." fee row charge park fees at 750 square feet. Government Code 66311.5 bars impact fees on an ADU of "750 square feet of interior livable space or less" and requires fees above that to be proportionate to the main home. The statute controls.
- Utility charges. The checklist says utility charges "apply to all ADUs." Under Government Code 66311.5(d), an ADU created inside existing space under 66323(a)(1) needs no new utility connection and no connection fee unless it was built with a new house.
- SB 9 approval. The City SB 9 page labels the plan type "Requires Planning Commission Approval" and says applications "typically take three to five months." Government Code 65852.21 requires review "without discretionary review or a hearing" and a decision within 60 days of a complete application.
- Old statute numbers. Section 10-1.2741 cites Government Code 65852.2 and 65852.22; the state rules now sit in 66314 and the sections after it.
Best For
- ✓ House lots with room for a detached ADU of 800 square feet with 4 foot side and rear setbacks.
- ✓ Garage conversions, which need no setbacks and no size limit under the checklist.
- ✓ RL lots with no tenant in three years, for two SB 9 homes plus ADUs.
Usually Fails When
- ✕ The SB 9 lot is outside RL or had a tenant in the last three years.
- ✕ The ADU plan treats the unit as a rental of less than 30 days.
- ✕ A detached ADU is designed over 1,200 square feet or above 16 feet away from transit.
What To Verify Before Spending Money
- → Whether the lot is within one-half mile of a major transit stop, for ADU height and SB 9 parking.
- → The rent review status of any existing home, for the SB 9 tenant test.
- → How the City applies the 750 square foot fee line to your ADU size.
Where to Go Next
Related on VanPlex: the Hayward overview, the California ADU law page and the SB 9 page.
Frequently Asked Questions
Does Hayward have its own ADU ordinance?
How big can an ADU be in Hayward?
How many ADUs can I build on a Hayward house lot?
Do I pay park fees on a Hayward ADU?
Can I sell a Hayward ADU separately from the house?
Does a Hayward ADU need its own address and meter?
Can I build two homes on my Hayward lot under SB 9?
Does SB 9 need Planning Commission approval in Hayward?
Does an SB 9 project in Hayward need a historic report?
Is a Hayward ADU covered by rent stabilization?
Official sources (checked October 2026)
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