the mill valley house cascades down the side of a steep hill in california

a series of cascading boxes are joined together to form this ‘multicellular house‘ by japanese architect koji tsutsui. perched on a 20-degree slope that overlooks a dense forest in mill valley, california, the mill valley house consists of 10 different rooms that together form a small village on the side of the hill.

the mill valley house cascades down the side of a steep hill in california

images by iwan baan



set over 1,500-square-foot, koji tsutsui & associates minimized the impact of the mill valley house by building it on galvanized steel columns, reducing the home’s footprint and the need for excavation. they also rotated each one of the 10 boxes to best fit the topography of the site, whilst maximizing on natural light. each box is a different room with a series of steps taking you from one space to the next.



there are three bedrooms in total and two bathrooms. the rest of the rooms include a kitchen, lounge area and other shared spaces. the interior is characterized by a mostly white color palette, aside from lightly stained plywood floors and green sofas.



situated on the southern edge of mill valley borders the golden gate national recreation area — one of the bay area’s most popular nature preserves – the home is surrounded by nature. a long staircase connects the house to the parking pad at the street above and once inside large windows allow for maximum natural light and exposure to the arboreal views.


project info


architects: koji tsutsui & associates

name: mill valley house

type: residential

location: mill valley, california

site: 1,500 sq ft

kieron marchese I designboom

aug 08, 2019