Home Additions in Sunnyvale, CA
Get a Free Sunnyvale Addition Consultation
When Sunnyvale Design Review Applies
Sunnyvale design review triggers: any new home; first-story additions over 50% of existing floor area; any new second-story floor area; new or changed second-story decks or balconies; new, moved or enlarged second-story windows other than street-facing; and major front-elevation or porch changes. One-story projects are decided by staff without notice. Two-story projects and second-story additions get public notice with a 14-day comment period, and the on-site posting must show a streetscape elevation with the houses on each side. Projects over the floor-area threshold go to a Planning Commission hearing. Sunnyvale adopted new single-family objective design standards in July 2026, so we confirm the current floor-area figures with the Permit Center for your lot.
Addition Work
Second Stories in Eichler Neighborhoods
Eichlers and single-story districts: Sunnyvale has roughly a thousand Eichler homes in tracts built from 1949 to 1968, including Fairbrae, Rancho Verde, and Fairorchard and Fairwood in Cherry Chase. The City publishes Eichler Design Guidelines, and owner-initiated Single-Story (S) Combining Districts limit homes to one floor, 17 feet and 45% floor area ratio.
If your street is in a Single-Story Combining District, such as the Dartshire-Devonshire Eichler overlay, a second story is not allowed, and additions must stay single-story under 17 feet.
Other Sunnyvale Rules
- Trees: a protected tree is 38 inches or more in circumference at 4½ feet (one trunk of 38 inches or all trunks totaling 113 inches). Removal needs a permit.
- Heritage housing: in the Heritage Housing district, demolition needs Heritage Preservation Commission approval; Taaffe-Frances and Murphy Station have their own guidelines.
- School fees: Sunnyvale School District requires a Certificate of Compliance before the permit is issued.
City Hall, 456 W. Olive Avenue, 2nd floor (north entrance), Sunnyvale, CA 94086
Building Safety (408) 730-7444 · Planning (408) 730-7440
Weekdays 8 a.m. to noon and 1 to 5 p.m. Applications, uploads, payments and inspections run through E-OneStop Online Services. Building inspections: online or (408) 730-7790; the general contractor schedules and attends every inspection.
Explore More
Other Sunnyvale services: Bathrooms · Kitchens · New Homes · Sunnyvale ADU builder · Sunnyvale overview
Same service nearby: Santa Clara · Mountain View · Cupertino
Sunnyvale Home Additions FAQ
Does a second-story addition need design review in Sunnyvale?
Yes. Any new second-story floor area triggers design review with a 14-day public comment period.
Can I add a second story in an Eichler neighborhood?
Not in a Single-Story Combining District; elsewhere, with design review.
Does a single-story addition need notice?
One-story projects are decided by staff without notice, unless they exceed 50% of existing floor area or other triggers.
Are trees protected?
Trees 38 inches or more in circumference need a removal permit.