Concrete Trees

I recently found myself in a local community center where my daughter takes dancing lessons. I was pleasantly surprised to find an iconic architectural element in a place I wouldn’t have expected it. Something akin to a concrete tree.

Jerusalem architecture circa the 1960’s celebrated the wonders of reinforced concrete and created some amazing details. In this case, an entire ceiling or roof held aloft by a single central column. The engineering logic is obvious. Trees rise from a single central column and spread their canopy outwards, providing protection. So why can’t a building?

The most famous Jerusalem installation of this detail is in the Israel museum.

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In this example, the central column not only provides structural support, but it provides a centralized location for mechanical, electric and plumbing elements to move vertically. The centralized structural system is celebrated by placing a ring of glass around the edge of the room separating the walls from the ceiling, thereby making it clear that the roof is supported by the central trunk and not the surrounding walls.

Tree-like morphology is present in many buildings, especially skyscrapers. Tall buildings are typically designed around a heavy condensed core with structural supports branching out towards a façade that is made of relatively thin, lightweight cladding. The structural core will frequently house the elevator shafts, stairwells, utility shafts, and (in Israel at least) security rooms. However, due to the scale of these buildings, the arboreal inspiration goes unrecognized.

As I waited for my daughter’s dance recital to begin, I admired the architect’s strategic use of this detail. Sure, it holds up the roof, but it also does so much more.

The space covered by this cantilevered roof is the entrance hall to the community center. It’s an in-between space, the meeting of inside and out. The natural light flooding in from all directions provides for ample warm light, not as bright as outside, but lighter than the ensuing hallways and rooms. The central column offers a focal point, providing orientation; and together with the stairs even anchors a vertical transition.

Very often designers are afraid of structure. Columns get hidden in walls, extensive and expensive efforts are made to eliminate columns. But every now and then a designer remembers that the structural elements are also crayons in his pencil box.