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Infrastructure With A Building’s Skin

Once in a while, the topic of plaster in nineteenth century buildings comes up on a project. The short version is that, with a few exceptions, the interior of building walls and partitions were plastered, and most of the time there were plaster, tin, or wood ceilings. Exposed wood roof or upper-floor framing was for barns; exposed brick was for the exterior. The most prominent exceptions are heavy-timber buildings, where the wood was exposed, but often painted to better reflect light. White-painted interiors made the best of the poor lighting of the era, and plaster provided somme real fire-protection. In other words, the modern style of exposed wood framing and exposed brick at building interiors would have looked very strange to our predecessors.

This difference between the modern acceptance of exposed building structure and earlier sensibilities sometimes shows up at building exteriors. The gas-holders I was talking about yesterday were exposed metal, the gas-holder in the picture above, in Troy, New York, hid the metal behind a brick facade. It was built in 1873, so it’s actually newer than the East 14th Street gas-holders from yesterday. Here’s an elevation/section that explains the basics:

The all-metal holders typically grew and shrank vertically as they filled with gas and then discharged it. This allowed the gas inside to stay at a constant pressure. If you put a building-like facade on the holder, having the roof move up and down would look very odd (as well as creating a rainwater problem when the roof dropped below the top of the wall), so instead there was an interior iron shell. The pulley system mounted to the interior piers allowed the shell to move. Here’s a view of the radial trusses of the roof and the pulleys and tracks on the piers below:

In short, this looks from the outside like a building – a slightly odd one, seeing as how it’s round in plan – but it’s actually closer to being a machine. The brick exterior allows it to blend in with its mostly residential neighbors. The fakery was carried further than a simple disguise would indicate: the elevation/section refers to a portico that had been removed before the HAER survey was performed in 1969.

This type of disguise (or fakery, if you prefer) ran into several problems. It was more expensive to build than simply allowing the actual object to be exposed, it required more maintenance, and it eventually ran headlong into the “structural honesty” philosophy.