Ridge House

Project Description

This remote 18-acre property in Sonoma County provides little naturally flat, buildable area. Though it complicates construction, the dynamic topography affords both expansive vistas and seclusion. Manzanita groves and pine-forested hillsides encircle a small plateau where the Ridge House and accompanying pool nest within their private panorama.

The owners are a growing family of five who enlisted the architect to create a unique perch to host their extended family. They requested three private guest areas, each with a separate entrance, en–suite bathroom, and outdoor terrace. To accommodate the separate suites, the building is composed of three distinct volumes.

Natural landscape and topography drive the design of this compact, sculptural guesthouse offering a deeply contextual solution. The site leads the form, and the building becomes part of the terrain. These volumes step down with the grade progressively, nesting into the natural contours so that the mass of the building is softened into the hillside. A continuous, multi-gabled roof joins the units into a coherent whole while its peaks and valleys echo the hills beyond.

Design Challenge

This project required a building that is resilient in the face of significant, adverse environmental demands, while embracing and framing the beauty that same environment has to offer. To strike the right balance, Mork Ulnes turned to the qualities of the primary material used in the construction of the building. Concrete is an inherently heavy material, yet its structural properties can enable incredible lightness. The design celebrates the material's contradictory qualities; one frontage of the Ridge House feels rooted and massive while the opposite is slender and soaring. From the shared perspective of the adjacent plateau, the three volumes are solid, concrete prisms. Upon entering and passing through a compressed, concrete threshold, the space expands and gives way to total openness and continuity with the landscape. The slim floor slabs, rooted in the hillside, float over the steep ground below and loft each bedroom into its own private plane of view. Diagonal roof ridges form elegant, folded planes that orient the space outward and upward to the picturesque hilltops in the distance. Glazed enclosures inscribe the conditioned spaces to enhance this spatial and material contrast: lightness alongside heaviness, allowing the concrete planes to remain the definitive architectural element. The pared-down design was able to dedicate little space for plenums or ducting because combined radiant heating and cooling presented an apropos, sustainable solution for thermal comfort. The hydronic system powered by a heat pump working synchronously with the building's thermal mass forms an ideal pairing of systems and creates a desirable environment year round with low energy loads.

Physical Context

Given the regional ecology and desire for a robust, lasting building, there was great concern about using fire-resistant building materials, especially at the roof. In response, concrete was chosen as the primary building material. The concrete’s organic tactility and inherent ruggedness root it into the rocky hillside. It's board-formed texture recalls the greyed wood siding on the property's main house. The building shell’s thermal mass and siting strategy capitalize on passive cooling and heating strategies. The house is situated to shield from solar exposure during the most intense summer months. Orienting the solid concrete frontages towards the summer sun–path creates a thermal buffer against solar heat gain during the day and shades the indoor-outdoor living spaces during this critical time. As the concrete is blasted by the sun throughout the day, it stores up heat to release when the temperature drops in the evenings. With the wild, untouched California hillsides comes the constant risk of wildfire. As the project was nearing completion, the 2017 Nuns Wildfire engulfed the property. The surrounding forests were devastated, the main house was significantly damaged, but the all-concrete guesthouse was unscathed. The natural landscape will take more than a decade to fully recover, but in the meantime, Ridge House will offer a refuge providing dramatic, peaceful spaces within its elemental shell.