Structure Height Limits: Castro Valley vs Hayward
How do structure height limits rules compare between Castro Valley, CA and Hayward, CA?
Castro Valley and Hayward have similar restriction levels.
Castro Valley, CA
Alameda County
Alameda County limits residential structure heights to 30-35 feet in most R-1 zones under Title 17, with stricter limits in hillside overlays. ADUs are capped at 16-18 feet per state law.
View full Castro Valley rules →Hayward, CA
Alameda County
Hayward limits single-family residential structures to 30 feet and 2 stories in most RS zones. Downtown and mixed-use districts permit taller buildings per the Hayward Downtown Specific Plan.
View full Hayward rules →Key Facts Comparison
| Fact | Castro Valley | Hayward |
|---|---|---|
| R-1 height limit | 30 feet / 2.5 stories typical | - |
| Hillside zones | Often 25 feet maximum | - |
| Detached ADU | 16 feet (state law) | - |
| Measured from | Average natural grade | - |
| Rooftop equipment | May exceed with conditions | - |
| RS max | - | 30 ft and 2 stories |
| Accessory | - | 15 ft typical |
| ADU | - | 16 ft baseline state law |
| Downtown | - | Up to 105 ft+ |
| Airport zone | - | FAA Part 77 limits |
Highlighted rows indicate differences between cities.
Castro Valley FAQ
Does a basement count toward height?
Generally no if it is below average natural grade, but a daylight basement that extends above grade on downslope sides may count as a story depending on exposure.
Can I add a second story to my Castro Valley home?
Yes if the finished structure stays within the zone height limit and does not violate hillside overlay restrictions. A building permit and often design review are required.
Hayward FAQ
How tall can I build my ADU?
State law baseline is 16 feet, with 18-25 feet allowed near transit or for two-story additions per AB 2221 and SB 897.
Do rooftop HVAC units count toward height?
Mechanical equipment can exceed the limit if properly screened and in line with specific zoning exceptions.
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