Preserving Modern Buildings

2030’s hot preservation project:

Interest in historic preservation of modern architecture is fairly recent, really getting going in the U.S. only in the last 25 years or so. This article on the restoration of a Louis Kahn building helps put some of that in perspective.

The distinction between architectural preservation and structural preservation seems to me to be sharper than usual when we talk about modern-building preservation. There are many difficult philosophical and technical questions for the architects: Should experimental details for then-new systems (for example, internal flashing for glass curtain walls) be recreated even if the experiment failed? What do you do if the architect who designed the building was publicly opposed to historic preservation? Should the buildings be upgraded to modern energy codes, even if they’re exempt as designated landmarks, because the logic of construction and energy flow were a large part of their design? If yes, where do you hide insulation in a building with a lot of glass and a minimum of poché space? If preservation philosophy says that interventions should be visually distinguishable from the original building, but the original building has an appearance of minimalist ornamentation, don’t the interventions damage the building?

For engineers, on the other hand, the more recently a building was constructed, the more its structure resembles current-day practice. The newer the building, the less that repair or alteration  work requires special knowledge or techniques and the more it resembles ordinary new-building analysis and design. I often describe our practice as general structural engineering for buildings constructed before 1950. That cut-off date hasn’t changed in a long time, not because modern buildings are uninteresting but because our expertise is focussed on pre-current practice.