Tree house

A tree house, tree fort or tree shed, is a platform or building constructed around, next to or among the trunk or branches of one or more mature trees while above ground level. Tree houses can be used for recreation, work space, habitation, a hangout space and observation. People occasionally connect ladders or staircases to get up to the platforms.

All great apes build tree platforms or nests as shelter from dangers on the ground, and the habit may have been inherited by humans. While no evidence of prehistoric human-made tree houses has been found, wooden structures would not have survived over time. In contrast, evidence of cave dwellings, rock shelters, and bonfires is detectable, but is notably scarce from before 40,000 years ago. This has led to the speculative hypothesis that archaic humans may have lived in trees until then. The skeletal changes due to the evolution of human bipedalism started at least four million years ago, but early bipedal hominins may still have spent some time in trees and retained some tree-climbing abilities. Early terrestrial bipedalism is supported by evidence such as fossilized bones and footprints (like the Laetoli footprints). According to the savannah hypothesis, this evolution happened as an effect of early humans adapting to life on the ground in savannah environments, partly for more energy-efficient locomotion.^{[citation needed]}

Even today, tree houses are built by some indigenous people in order to escape the danger and adversity on the ground in some parts of the tropics. It has been claimed that the majority of the Korowai clans, a Papuan tribe in the southeast of Irian Jaya, live in tree houses on their isolated territory as protection against a tribe of neighbouring head-hunters, the Citak. The BBC revealed in 2018 that the Korowai had constructed some very high tree houses "for the benefit of overseas programme makers" and did not actually live in them. However, the Korowai people still build tree houses, not elevated but fastened to the trunks of tall trees, to protect occupants and store food away from scavenging animals.

Trees have historically been integrated into the construction of buildings, for example the walls of a chapel, to provide support to a structure built around them. Chêne chapelle is an example of this practice. Modern tree houses are usually built as play areas for children or for leisure purposes, but may also be used as accommodation in hotels or residential applications. In this case, the main part of the structure is built with more typical construction materials. The use of tree houses in this manner is part of a movement towards the practice of "living architecture".

Tree houses may be considered as an option for building eco-friendly houses in forested areas, because unlike more typical forms of housing, they do not require the clearing of trees.^{[citation needed]}

There are numerous techniques to fasten the structure to the tree which seek to minimize tree damage.

The construction of modern tree houses usually starts with the creation of a rigid platform, on which the house will be placed; the platform will lean (possibly on the corners) on the branches. In case there are not enough suitable supports, the methods to support the platform are:

Struts and stilts are used for relieving weights on a lower elevation or straight to the ground; tree houses supported by stilts weigh much less on the tree and help to prevent stress, potential strain, and injury caused by puncture holes. Stilts are typically anchored into the ground with concrete, although new designs such as the "Diamond Pier" speeds installation and are less invasive for the root system. Stilts are considered the easiest method^{[by whom?]} of supporting larger tree houses and can also increase structural support and safety.^{[citation needed]}