This project added a detached two-story, 983 sq ft, 3-bed / 3-bath ADU to a tenanted single-family property in San Jose, a layout that drives the strongest rental returns in this part of San Jose.
The project is also structured for a future condominium conversion under California’s AB 1033 framework, with the ADU built on its own independent utility connections from day one — so the main house and the ADU can later be separated into two individually titled, individually salable condominium units.
Because the main house was tenant-occupied throughout the build, the site plan and phasing had to work around their continued daily use. Front-yard utility lines were trenched and backfilled early in the schedule so tenant parking access could be maintained without setting up a temporary parking area. Construction fencing was phased and relocated as the build progressed, with safety protocols and scheduled-visit procedures established up front.
Hardie Board Vertical Siding
Quartz Countertops
Grey Shaker Cabinetry
Split HVAC System
Rooftop Solar
Luxury Vinyl Plank Flooring
Built Condo-Ready Utilities
"Progress has been much faster than I expected. Thanks to the whole Apex team — their construction crew has been genuinely reliable from start to finish."
Can I build a two-story ADU in California?
In most cases, yes. California state law makes ADU approval ministerial — meaning by-right, not discretionary — and explicitly permits two-story builds on most single-family lots. Detached ADUs can reach 18 feet near transit, 20 feet if needed to match the main house's roof pitch, and up to 25 feet in some configurations. Cities can set design and setback standards but cannot deny a two-story ADU on height alone.
The practical limits come from your specific lot. Setbacks, second-story privacy rules, daylight planes, fire access, and tree protection can all shape what a second story looks like in plan — and on smaller lots, the upstairs footprint may end up smaller than the downstairs.
A feasibility study early in the process is the cleanest way to confirm what your lot can support.
How much longer does a two-story ADU take to build than a single-story?
Plan for roughly 4–8 additional weeks on the construction side, and possibly more on the permit side.
The build is longer because a second story adds:
- Framing, sheathing, insulation, drywall, and finishing labor for an entire upper floor
- More substantial structural engineering (heavier loads, more shear walls)
- Additional inspections at each phase
- Scaffolding for siding and exterior work at height
What should I know about building a two-story ADU in San Jose?
San Jose allows two-story detached ADUs up to 25 feet tall on most single-family lots, and the city's ADU program is one of the more streamlined in the Bay Area. A few specifics shape design more on a two-story than a single-story:
- Privacy windows.
- Second-floor balconies and decks.
- Front-door placement.
- Solar and fire access.
Our 983 sq ft 3B3B in San Jose 95117 was designed around all of these from day one.
You’ve seen what’s possible—now let Apex Homes handle the details. From initial concept to precision construction, we build custom homes tailored perfectly to your lifestyle and future goals.
