Two Detached ADUs in Hayward (AB 956, 2027)
Plan Two ADUs in Hayward: Free Site Assessment
Hayward ADU rules today (2026)
From January 1, 2027, state law (AB 956) requires cities, including Hayward, to approve up to two detached ADUs on a lot with a single-family home. Hayward’s ADU checklists rely on state law, and the ADU ordinance the state has on file for the city dates from 2017. Here is what that means for your project.
- Units allowed now: one ADU plus one JADU on a single-family lot (city ADU checklist, revised April 2024).
- Sizes (new construction): 850 sq ft for a studio or one bedroom, 1,000 sq ft for two or more bedrooms. Above that, the lesser of 50% of the main house or 1,200 sq ft. JADUs are up to 500 sq ft; conversions have no limit.
- Height: 16 ft for a detached ADU, or 18 ft within a half mile of transit. Attached ADUs follow the zoning district.
- Setbacks: 4 ft side, street-side and rear. Front setback follows the district.
- Separation: the checklist asks for 5 ft from other structures.
- Fire separation: attached ADUs need a 1-hour fire-rated wall and no interior door to the main house. Detached ADUs must meet the residential code’s fire separation distance.
- Process: apply through Hayward’s e-Permit Portal, where review status is posted.
- Pre-approved plans: the Hayward ADU Plans Gallery. You submit the purchased plan set with a site plan and foundation details.
State review of Hayward's ADU rules
On October 8, 2025, HCD sent Hayward a technical assistance letter. It noted that the most recent Hayward ADU ordinance on file is from 2017, that it may be outdated and out of step with state law, and that an ordinance that does not comply is “null and void.” In that case, state ADU standards apply. The city’s response was due November 7, 2025. We did not find a newer adopted Hayward ordinance. In plain terms: where Hayward’s local rules conflict with state ADU law, the state standards control. Where local rules are stricter than state law, state law applies.
Recent Axiom work
Professional photos from a recent Axiom Renovation full remodel and addition in Los Gatos.
What changes on January 1, 2027
AB 956 raises the number of detached ADUs Hayward must approve on a single-family lot from one to two, both new construction. Each may be limited to 800 sq ft of living space, local height limits can still apply, and side and rear setbacks can be no more than 4 ft. Where two detached ADUs are built, a JADU on the same lot does not have to be approved. The law also includes protections for owners in homeowners associations.
Hayward’s current checklist allows one ADU. AB 956 adds a second detached unit. Hayward’s new-construction sizes of 850 to 1,200 sq ft are above the 800 sq ft each unit may be held to in a two-unit project. The 5 ft separation in the checklist will matter when two units and a house share one lot, and any local rule that conflicts with state law gives way to state standards. Hayward will need to update its ADU rules, and we will confirm the current requirements as it does.
Planning two detached ADUs on a Hayward lot
- Sprinklers: an ADU needs sprinklers if the main house has them or the work triggers them.
- Energy rules: Hayward’s Reach Code applies to new ADUs, so plan the electrical design early.
- Electrical: two ADUs usually need a load calculation and often a service upgrade.
- Addresses: each ADU gets its own address.
- Fire, water and sewer: Hayward’s ADU page has a Fire Department checklist and water and sewer handouts. We review them for each lot.
- Use and sale: ADUs cannot be sold separately, and rentals must be longer than 30 days.
Building ADUs in Hayward with Axiom
See our Hayward ADU builder page and our Hayward service area, read the AB 956 overview, or compare nearby Castro Valley and Union City.
Process
Our ADU Process
Step 1
Initial Consultation
We begin with a thorough initial consultation to understand your needs, assess your space, and discuss your vision, budget, and timeline.
Step 2
Planning and Design
At Axiom Renovation, we understand that the planning and design phase of an ADU project is crucial to its success. Our dedicated project managers will work closely with you to understand your goals, design ideas and budget for the project.
Step 3
Material Selection
We guide you through selecting high-quality materials that fit your design and budget, ensuring durability and aesthetic appeal.
Step 4
Demolition and Preparation
Careful demolition and preparation work are performed to ready the space for construction, minimizing disruptions and ensuring a clean work environment.
Step 5
Construction and Installation
Our skilled craftsmen handle the construction phase, including obtaining permits, scheduling appointments, and the actual construction and installation with precision, building the new space according to the approved design.
Step 6
Electrical and Plumbing Work
Licensed professionals conduct all electrical and plumbing work, ensuring everything is up to code and seamlessly integrated into the new ADU.
Step 7
Painting and Finishing
We pay close attention to detail during the painting and finishing stage, ensuring all surfaces are properly prepared and beautifully finished.
Step 8
Fixture and Appliance Installation
We expertly install all fixtures and appliances, ensuring they function correctly and fit perfectly with the overall design.
Step 9
Final Touches and Clean-Up
Final touches are added, and a thorough clean-up is performed, leaving your new space pristine and ready for use.
Step 10
Final Walkthrough and Client Satisfaction
We conduct a final walkthrough with you to ensure every detail meets your expectations and address any remaining concerns, ensuring your complete satisfaction.
Hayward Two-ADU FAQ
Can I build two detached ADUs in Hayward?
From January 1, 2027, AB 956 requires Hayward to approve up to two detached, new-construction ADUs on a single-family lot that meets objective standards. Today Hayward’s checklist allows one ADU plus one JADU.
How large can each ADU be in Hayward?
Today a new ADU can be 850 sq ft for a studio or one bedroom, 1,000 sq ft for two or more bedrooms, and in some cases up to 1,200 sq ft. Under AB 956, the city may limit each of two detached ADUs to 800 sq ft of living space.
Does Hayward have its own ADU ordinance?
The ordinance HCD has on file for Hayward is from 2017, and HCD warned in October 2025 that it may be outdated. Hayward’s checklists cite state law. Where local rules conflict with state ADU law, state standards apply.
How tall can a detached ADU be in Hayward?
16 ft, or 18 ft within a half mile of transit.
Does a Hayward ADU need fire sprinklers?
Only if the main house has sprinklers or the work triggers them. Detached ADUs must also meet the residential code’s fire separation distance.
Who builds two-ADU projects in Hayward?
Axiom Renovation designs, permits and builds ADUs in Hayward and is planning two-unit projects for 2027. Call 408-702-2022, Monday to Friday, 9 am to 5 pm.
Sources: AB 956 (Quirk-Silva), signed September 29, 2026, effective January 1, 2027, as summarized by Brownstein Hyatt Farber Schreck and California YIMBY; Hayward ADU page; Hayward SFR ADU checklist; HCD letter, October 8, 2025. This page is general information, not legal advice. Local rules change; we confirm current requirements with the city for every project.