Every building technology is ultimately a compromise. Hundreds of factors weigh in. Faced with similar situations, vastly different cultures will reach the same conclusions: take the thatched roofs of the N. Atlantic Hebrides and those of Jeju Island in the Korea Strait for ex.
Both areas are characterized mostly by strong winds and relatively meager soils. Hence roofs were thatched (which grows amply on poor soils) and built with a low angle (nearly flat) with an oblong shape weighed or tied down with a net of rope to minimize the effect of winds.
Normally the primary purpose of a roof is to shed water but here that job had to take second place: longevity is sacrificed in order to ensure that roofs can survived hurricane or typhoon strength winds. Rain permeates the thatch so in the case of Jeju, they only last 1-2 years.
The short lifespan of a Jeju roof is no problem. Nature has provided it so neatly that the thatch used is best cut in December when agricultural activity is at a nadir. Anyone can help, technically simple, the ropes of an average roof for example take four people one day to make.
Another bonus is that the thatch is perfect in the hot and humid summers with cold winters on Jeju Island: the thatch keeps the summer heat from penetrating into the interior of the home and in winter it isolates the heat from people and stoves.
When the roof is relaid the bad parts are thrown out and the new thatch easily spread over the existing roof. Nothing goes to waste: the old thatch is thrown into the household pigpen where it mixes with manure and is then carted to the fields and gardens to make free fertilizer.
But the final bonus is that the very act of thatching a roof becomes a communal village event where people get together and help each other, strengthening the ropes on your neighbor's house literally strengthens the bonds between your families. This is mostly a lost art today.
The houses of Jeju Island are interesting: clustered together in villages as walled family compounds. The walls are to keep cattle and wind out, for gardening purposes. One house is the the young family and a rear house is given over to the older generation.
The walls are built out of black volcanic rocks with the local red soil as a clay mortar. The gates have three poles: one pole in place means the household is out for little, two means out for the day, three means out for a long period of time.
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Went to look at a possible source of thatching materials. This stand was last harvested by a village about a century ago. Unfortunately the soil here is poor in minerals and having been left to grown wild for so long the material is of quite low quality: not worth the effort.
There used to be a village here, growing rice and herbs and vegetables and foraging for food and materials in the mountains. Today all that remains are some old stone foundations and pieces of pottery. This piece comes from a tea cup ca. 17th-19th century. Unearthed by moles.
Another sign of the village that once were: there was a stand of windmill palms nearby. These trees were used to make the rope that thatchers and carpenters needed to build the mostly round timber roofs. Quick and easy the rope lasts for centuries and can be composted at the end.
Cobble-streets perform an invaluable service during flood events. Studies measured them to have a steady infiltration rate of 65mm/h: this means that an average city slope of asphalt (0mm/h) is a rapid river after 30min of heavy rain while a cobble-street would suck it all up.
However, natural forest soils are incredible sponges and can store unbelievable amounts of water during storm events. But run these soils over with heavy forest machinery for a decade or so and the soils gets so compacted it isn't much more impermeable than a city cobble-street.
Some desert soils are so compacted by millennia of grazing animals, wind and rain that they aren't much more permeable than tarmac. Unless you see it for yourself you have no idea how hard desert soil can get.
The future must be sustainable or there will be no future at all. Agroforestry is the practice of combining slow growth forest (which can take generations to mature) with agriculture, solving many practical ecological, technical problems. In Taiwan, agroforestry is growing.
In in Hualien County a private 6ha butterfly reserve is being used to also grow indigo plants, which were a major cash crop until about a century ago. Underneath the trees indigo plants provide food and shelter for the butterflies: excess indigo leaves are harvested and sold.
Indigo prefers full sun but in hot climates it grows well in shade. In nearby Okinawa indigo is grown with great success in citrus tree orchards, doubling the output of the farms for very little extra labor and investment.
Tsurumi River between Yokohama and Tokyo regularly flooded with devastating results until a new concept was trialed in a huge project started in 1985 and completing in 2003: the Tsurumi River Multipurpose Retarding Basin. Covering 84ha it functions as a flooding control zone.
To call it successful would be an understatement: here's two charts, one of maximum two day rainfall, one of number of flooded buildings. Both cover the same time period. Red line represents the start of construction.
Normally the zone is a park containing a raised stadium and sports facilities as well as nature walks, wildlife etc. During the 2019 mega-typhoon the basin which holds 3.9 million m³ (the equivalent of a power dam) of water received 0.94 million m³, well within its capabilities.
The largest irrigation pond in Japan was hand built in 704 A.D., Manno-Ike, in present day Kagawa Prefecture. Still in use it has been rebuilt many times. It regulates water from scarce rainfall, counters droughts, stops flooding, and makes large scale rice production possible.
Kagawa has a peculiar climate: the southern mountain range blocks monsoon summer rains (when rains are most needed) and the fierce summer sun makes rice production nearly impossible. When rain falls, it rushes down the mountains, floods the plan and exits. Hence ponds were vital.
In the 7th c. Kagawa was famously inhospitable with heat waves, droughts and floods. Manno-Ike was built under the Imperial Governor Michimori-Ason. Today, 14,600 large irrigation ponds (1 for every 65 persons) and 5,000-10,000 small ones, have been hand dug over the centuries.
“The ‘free’ market is, of course, nothing of the kind. It’s unfree in at least two crucial senses: first, in that it’s compulsory; second, in that it’s expensive.”
— John Michael Greer, Dark Age America, 2016
Many believe that, for example, cars must be good because the market favors them, or that traditional building techniques are too expensive and that is why the market disfavors them. The above tweeted map is an illustration of just how "free" the market is to make these calls.
Me everyday: "Let's build human scaled towns."
Twitter replies everyday: "LOL if people wanted that the market would provide it."
Hence this thread.