Mountainside House | Hill Thalis Architecture + Urban Projects

Sited on a beautiful mountainside two hours south of Sydney, Australia, this house surveys an extraordinarily varied landscape; a dramatic sandstone escarpment to the north; a steep, forested valley to the northwest, and broad, agricultural plains and the coastal horizon to the east. A slim form is placed so that its long axis is oriented to the moment on the horizon where land meets water. The site's steeply sloping topography is modified by a series of landscaped terraces that create a place for the more pure geometric form of the building to rest, and provide level, sheltered outdoor spaces that anchor the building into the mountainside and offer respite from the strong northwesterly winds. To the east the house is suspended, hovering above the more open landscape of the distant farms, townships and coastline. Day-to-day life in the house is characterised by movement between the contrasting intimacy and drama of these two conditions. The envelope of the house is a series of frames that offer focused encounters with distinct landscape elements. The frames take their scale cues from their particular outlook and make a series of habitable edges to the surrounding garden, terraces and landscape. These threshold spaces are considered as ‘rooms’ having equal importance to those within the house itself. From the interior of the house these spaces also conceal sliding doors and shutters that allow the house to draw in or exclude a changeable series of longitudinal and diagonal landscape vistas in response to light, mood and weather. Shutters and screens provide bushfire protection, but are more generously conceived as devices to adjust the house’s microclimate. The depth of the thresholds allows many of the doors to remain open during rainfall so that the house is constantly filled with the sounds and scents of the surrounding bush. The house is designed for four adults to occupy fulltime, but a small library room can be extended to form a large dormitory to accommodate family and friends in holiday periods. Self sufficient in terms of water and waste, the property provides multiple energy sources for heating to minimize power usage. A muscular concrete and blockwork shell structurally anchors the cantilevers and provides bushfire protection. Within, burnished plaster subverts the weight of the concrete, glancing light and reflected views along walls. Limed plywood blade trusses amplify early eastern and late western light captured through venting clerestory windows. Plywood and timber finishes line bedrooms to soften the enclosure of these contained spaces of retreat. Externally, recycled Australian hardwood and brickwork leaven the concrete shell with integrally muted, richly textured and weathered natural finishes. Regeneration and weed control has reinstated the bushland fringes of the site, while closer to the house brightly coloured and perfumed cultural plantings are beginning to spill over the terrace walls. The client’s family has made a series of dry stone walls from boulders collected during construction, gently formalising pathways and stopping points along the site’s northern edge.