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Kurt's avatar

Wow. This is really good. I've got a mountain of general notes on rural housing, but haven't ever put it all together into a coherent essay.

One of the (depressing) things I see everywhere in Hubei is the standard concrete box floor plan (1st fl. center entry/parking/utility, 2nd fl. and higher floors living space)...OK, everyone is allowed to do what they want with floor plans... but with bizarre faux Western referenced architectural details slapped on as decoration. Turned spindle balustrades everywhere, goofy ornate baroque rococo window details, utterly inappropriate dentil and architrave details, concrete fluted columns mixing Doric, Ionic, and Corinthian details in the capitals, columns with no entasis, etc., etc. Sometimes the details are painted gold, and if not gold, some bright color.

All of which is ok if that's what someone wants, but it's a little depressing when there are so many traditional Chinese architectural details that could be applied.

The larger issue is one of building science. The original architectural designs employed materials that, while not necessarily keeping water out, at least allowed drying. Pure lime parging on the exterior of rammed earth/mud brick/masonry unit construction worked remarkably well as it had for a couple thousand years. I'm seeing the old structures that survived now eschewing lime and instead being coated with elastomeric barrier paints that retain moisture, not allowing the buildings to dry.

Cast concrete has specific performance characteristics, one of them being they are reservoir materials, meaning they absorb and retain water. This is fine if you use appropriate sealants that allow vapor movement and drying capability. We have those sealants. The problem is everyone is applying high tech elastomeric barrier sealants thinking they're just going to seal all water out, not understanding that these materials do allow incremental moisture in, but retain the moisture and do not let it dry. The worst are the "vapor barrier sandwich" with sealant on both the exterior and the interior.

Western building methods made this same mistake all through the 90's and early aughts, and now the same thing is happening in China. We know exactly how it works. It doesn't work. Or, more accurately, it retains moisture and in the long term you get remarkable amounts of mold and poor indoor air quality (IAQ). Expect this to be an issue that folks start understanding in the future. I'm seeing it now in urban settings where they glue the fake brick onto concrete substructures, and the fake brick flakes off after a few years because it doesn't allow drying.

(My career was spent in building performance analysis. These new rural buildings are problematic beyond just their lamentable design aesthetic and loss of traditional cultural heritage.)

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Ruby Wang's avatar

This is a great piece thanks Nathan. My father restores 老房子 from Jiangsu, in Hangzhou, and I am trying to make a documentary about the process and his endeavours across 25 years. If you have other insights pls do share

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