The Forbidden City Beijing - Some Construction Insights

The forbidden city in Beijing is a massive walled compound of some 960 x 750 metres containing over 900 buildings.  It is the centre of the ancient capital and was built between the early 1400's and completed two hundred years later.

It's main attractions now for tourists are the series of palace buildings which are wooden structures in the main with the wood covered in what we might call a gesso, presumably a clay based plaster which conceals the wood and allows for decoration.

The wood used for the massive beams and columns is Phoebe zhennan, a member of the Lauraceae family (as is Camphor Laurel, Cinnamomum camphora also a Chinese tree revered in China, introduced to Australia in the 1840's and now officially a weed species in many regions because it is so invasive). Phoebe zhennan is endemic to China and now a protected and valued species threatened by habitat loss.

I was intrigued to see 'into' one of these columns via a hole in the plaster into which no doubt thousands of fingers have probed.  It indicates the problems of cladding wood, which is seasonally unstable, with a plaster which presumably is a dimensionally stable coating. The maintainance is bound to be an ongoing chore because the wood is continually changing dimension and cracking the plaster.