California Onsen House

Axonometric View of Site
This project is a take on Japanese design for California living. It is an addition to an existing single family home for a family of 3.

On a small lot, the addition is conceived around connection to outdoor space to maximize spatial quality. It also manifests two unconventional user requirements: A japanese hot tub room, “Onsen”, on the ground floor and split level, tatami-like, bedrooms on the upper floors.



View of garden from the Sitting Room, with the Onsen in the background

Ground Floor Plan
The kitchen on the ground floor serves the dining room on the second floor with a dumbwaiter. This is a practical feature with an eye for aging in place.

Second Floor Plan
There is a roof deck outside the Dining Room and another outside Bedroom 1. With the Breezeway on the ground floor, these interlocking outdoor spaces are meant to orient the compact interior spaces towards more expanded light and views

Third Floor Plan
Bedroom 3 will have a view of the San Francisco Bay. The bathrooms on the 2nd and 3rd floor are both “decomposed” bathrooms, with the sink and vanity separated from the lavatory and shower. This not only takes advantage of the hallway circulation space for floor area, but also allows more than one person to use each “bathroom set” at a time. One answer to sleepovers and morning rush bustles.

View of Dining Room
Carefully placed large accordion doors/windows on either side of the dining room expand view and brings the outdoors in.
The dumbwaiter from the ground floor kitchen is tucked right outside the left wall.


View of Bedroom 1
The split level design allows access from a lower floor level, with a built-in desk on the right. While around the corner, the higher level leads to the vanity and central stair.

View of 2nd Floor Roof Decks
The built-in desk in Bedroom 1 projects from the main massing as a cantilevered volume.
There is an exterior stair for ease of bringing up supplies for a container vegetable garden up to the roof deck.

View of Roof Deck outside Dining Room
Overhangs are carefully sized to East Bay solar angles at different times of the year. The Dining Roof Deck will be warm and sunny during winter, cool and comfortable during summer.

View of Street Facade
The vanity component of the “decomposed” 2nd & 3rd floor bathrooms are allowed more openness due to separation from the private functions. They are expressed as cantilever volumes with views to lush city trees.

View of Exterior
The flexible outdoor spaces, roof overhangs, charred wood siding, expression of geometry through windows, fence, guardrails is a take on Japanese design for California living.