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Architecture: Boulders support the roof

Granite boulders carry the roof of the Mestizo-Restaurants in a Santiago de Chile city park.(July 2009) Whenever a Restaurant is built in a city-park, bridging the interior and nature on the outside is the order of the day for architects. In a sense it’s all about bringing nature and culture together. And, of course, the architecture should lure visitors inside.

Smiljan Radic solved this task masterfully in the Mestizo-Restaurant in Las-Américas-Park of Santiago de Chile: the roof of the building is cradled on granite boulders the likes of which could be found anywhere in the park.

The static engineering is particularly noteworthy. BusinessStone.com asked the project’s engineers: can boulders support the weight of an entire roof construction? – and what about the danger of faults in the stone?

Luis Soler of Luis Soler Engineering calculates: 50 kg/cm² must be supported by the boulders in Mestizo-Restaurant, that’s not much compared to the 500 kg/cm² which granite is usually meant to support. This particular stone carries the seemingly unfitting name of „Ala de Mosca” („Mosquito wing”) and stems from a quarry in Pirque close by.

Top and bottom of the boulders were honed down and set into the foundation by means of iron round-bars. The same connection was used to steel-mesh-concrete of the roof girders, which is camouflaged by wood grain exterior texture. Possible seismic loads are absorbed by the back of the building.

Keeping with the natural touch, the boulders used have various sizes. Some weigh in at 10 tones. On the other hand, the boulders are visibly formed by man, drawing architect critics to compare this construction with Karyatid where sculptures of women carry the roof of the temple.

Smiljan Radic (Mail)

Bureau Luis Soler (Mail)

Photos: Gonzalo Puga (Mail)

Note: honourable mention is also due to a building where raw stone blocks were implemented in a most unusual manner: seemingly formed by Cyclopes hand is the award winning SGAE building in the Spanish city of Santiago de Compostela. The building was completed in 2002 by the Spanish architects Ensamble Studio.