The Blasens start their intelligent designs with a detailed study of the site, its northern and southern orientations and seasonal microclimates. They believe in having a “light touch on the land,” as they say, so they often recommend building in the same footprint as a pre-existing home. Then they work around natural landmarks such as saddles in the hillside and major trees. For their own treehouse of a home in Marin County, they focused on framing their view of Mount Tamalpais and displaying the property’s California live oaks, black oaks, and valley oaks. They “edited the landscape,” as Silvina puts it, by removing invasive plants and failing species, then created “rooms”—sitting areas for different times of day and occasion—through hardscape features like crushed stone paths, concrete board-form retaining walls, and diverse garden furniture. Their softscape interventions included the planting of a harmonious spectrum of native and climate-adapted plants such as ceanothus and manzanitas.