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Heat and dust: Casa Caldera by DUST Architects

AR House 2016 finalist: an ‘off-grid’ home in Arizona defers to the land and the light

On the fireplace ledge of the Casa Caldera is the bleached skull of a javelina. The client of the 100m2 house found the remains on a walk around his property, about 20 miles from the border of Mexico in the San Rafael Valley. The skull reflects the lawless beauty of this landscape: the remoteness, heat, and aridity.

Driving to the house, two hours south of Tucson, is a trek that ancient Native American cultures must have experienced, save for the US Border Patrol SUV parked on a parked slope. For miles, the only sights are rolling hills dotted with oak and cottonwood trees and grassland bounded by distant mountains.

Conceived and constructed by DUST, a Tucson-based design build firm founded in 2007 by Cade Hayes and Jesús Robles, Casa Caldera doesn’t emerge from this landscape until you are almost upon it, through a gnarled grove of trees. Set into a hill, the rectangular, flat-roofed, one-storey structure is made of a board-formed concrete blended with a lightweight volcanic aggregate called scoria. Because the client was adamant that he wanted mass and no air conditioning or electricity (in the end, the architects had to wire the house and connect it to a portable PV array for insurance purposes), Hayes and Robles struggled to arrive at a scheme. ‘It was scary as we had the architecture and the construction liability,’ says Robles. ‘We were held to the fire to make this thing perform for human comfort. You’re in Arizona, dude!’

‘From the start, the theme of the house was vulnerability’

The architects found their solution in the zaguán, an urban prototype that spread north across Mexico’s border. Its defining feature is a wide central hall – the zaguán – that connects the entrance with a rear courtyard, a terrific means of natural cross ventilation. For Casa Caldera, DUST fabricated weathered, bifold steel doors with leather-wrapped handles at either end of the zaguán, which can be closed off or opened to control the temperature. ‘We had originally designed sliding doors, but after seeing the walls there was an intuitive feeling that you can’t attach anything to this, it needs to be pure,’ says Hayes. He adds that rented board forms cut down on waste and provided the rough, imperfect texture to the scoria that he and Robles wanted. Its shimmering, silvery surface changes with the light.

Site plan

Site plan

The architects partly wrapped the zaguán in termite and rot-proof reclaimed sassafras wood. To the north of the corridor is a living room/kitchen enclosed with a custom steel-framed window wall with a transom and floor-level steel kicks that open out into the zaguán to help circulate air. The private southern volume contains two bedrooms and a bathroom. For shade, operable windows are set back into the 450mm-thick, insulated and rebar-reinforced scoria.

Casa Caldera’s owner grew up visiting his grandparents’ ranch in the San Rafael Valley, and the desire to have a retreat here was partly sentimental. When the ranch was divided and sold, he purchased roughly 50 acres. A wine-maker by trade, he maintains a small vineyard on the property and hopes to hunt quail and return to another passion, falconry. ‘It was a long process,’ says the client. ‘I talked to a lot of different architects. I thought about containers for a while.’ The far-flung location and the client’s tight budget and off-the-grid demands were a deterrent to designers, until he met Paul Weiner, a respected architect and builder in Tucson, who passed the project on to Hayes and Robles. The two had been renting office space from Weiner and working with him on various projects. ‘Paul is one of our elders that we lean on and learn from,’ says Robles.

The skull reflects the lawless beauty of this landscape: the remoteness, heat, and aridity

Hayes grew up in New Mexico, Robles was born in Fort Huachuca, Arizona. Friends since their days at Texas Tech College of Architecture, the pair have a brotherly rapport. When Casa Caldera’s client approached them, the architects had what amounts to a smash hit with their first built project, an award-winning 400m2 rammed-earth house in Tucson – an unusual feat of craft and sensitivity.

Hayes and Robles could be seen as the newest generation of the ‘Arizona school’, a phrase coined about 15 years ago by Reed Kroloff, an architect and former director of Cranbrook Academy of Art and Art Museum. Kroloff identified a lineage of architects in the state who designed and continue to design in deference to the land and light, with a scrappy industriousness, and in honour of Arizona’s complex cultural traditions. These include Frank Lloyd Wright, Al Beadle, Paolo Soleri, Will Bruder, Jack DeBartolo Jr and his son Jack DeBartolo 3, Wendell Burnette, Judith Chafee, brothers Eddie and Neal Jones, and Rick Joy – for whom Hayes and Robles used to work. ‘The Arizonistas can bow to a dramatic site or abstract an environment in a provocative pose – both are legitimate and dramatic additions to the landscape if they’re done well,’ wrote Lawrence W Cheek in the May 2002 issue of Architecture.

Casa Caldera is an example of the former. From the start, the theme of the house was vulnerability. The valley was formed by calderas, volcanic craters that created the canyons where Apaches once roamed and now ‘the narcos are using’, says Robles. ‘The land here seems important, in reading it and relating to it.’ Protecting the house from the shadow of that subculture, as well as migrant traffic, was DUST’s first consideration. It determined the house siting: low enough not to be seen from a southern forest road, but high enough to have a view of the horizon. The steel doors and horizontal steel louvres on the windows add a subtle layer of fortification. A tradition of defensive architecture here – from the elements and from attack.

‘For miles, the only sights are rolling hills dotted with oak and cottonwood trees and grassland bounded by distant mountains’

Next, the architects had to determine a cost-effective and strong building material. While adobe might have been cheaper, it wasn’t as streamlined as scoria, which was used for the 800mm footers and the walls and could be poured with a three to five-person crew (adobe would have required concrete footers and a team of 10 to 12). The drama of the structure’s location hit home once construction started. What should have taken six months took two years. A broken scoria mixer was a setback. There’s only one, developed by the scoria aggregate creator Paul Schwam. Hayes and Robles described a harrowing scene of dumping buckets of the mixture by hand until they negotiated to have the machine fixed. Then there was the problem of getting supplies and contractors to such a remote location. Robles recalled seeing their first concrete shipment pass by, heading to Mexico. A map reading something like ‘turn at the cows, take a left at the windmill’ wasn’t always interpreted correctly. In the end, the architects say the prolonged construction was to their and the client’s benefit. ‘We really got to question each moment. It stretched us,’ says Robles.

Part of that was figuring out power and water. The house is fed by a natural well. A septic system has a leech field that will benefit vegetation. The standing seam roof funnels water to trees to shade the house, and a propane tank heats water. While he’s only come to Casa Caldera a few times, the client is happy with the results and hopes to make his visits longer. ‘It’s nice to see how the light comes through the openings at different times of the day and year,’ he says.

Architect: DUST - Cade Hayes, Jesús Robles

Carpenter: Jay Ritchey

Concrete and mason: Agustin Valdez, Ben Gallegos

Photographs: John Wagner 

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