Marin Horizon School

The expansion of Marin Horizon School, a Montessori school located in unincorporated Mill Valley, California, offers much-needed classroom space and defines the central outdoor space on the campus. The new 14,000 square foot structure provides new classrooms for the 4th through 8th grades, including specialized science, art and music classrooms.

Instead of siting the new building in the center of the campus, it replaces a temporary building at the northwest corner of the site with its south elevation aligned with other existing school buildings. The back of the building is embedded into the hillside to reduce the visual scale of the project to the adjacent residential neighborhood. The new building along with the new amphitheater on the west edge of the site help frame the playground space and provide a large outdoor gathering space for the school.

Taking advantage of the temperate climate in the region, the circulation to the building is outdoors which reduces the amount of energy used to condition the indoor space. This configuration also offers glazing on two sides of the classrooms, improving the amount of natural daylight and the overall quality of the spaces. The long overhangs on the south elevation block direct sunlight and heat gain into the classrooms and provide the circulation areas with shelter from the sun and elements. A covered deck space on the east end of the second floor houses lockers and is a favorite informal gathering space for the students.

The two story building provides new 4th and 5th grade classrooms on the ground floor adjacent to the new music and science classrooms. The middle school, comprised of 6th, 7th and 8th grades, is on the second floor, which overlooks the playground and creek to the south and faces the hillside to the north. A resource room complete with a teacher preparation area is located on the third floor and is connected to all the other classrooms by way of an open stairway and elevator.

The music and science wing is designed in concrete masonry. As such, it serves the acoustic isolation needs and provides the bulk of the seismic support, allowing the classrooms to have large, offset and playful, glass window openings.


Project Type


Mill Valley,