A Bivouac is a shelter constructed of natural materials. Often utilising a structure of branches to form frame, which is then covered with leaves, ferns and similar for waterproofing and duff (also known as leaflitter) for insulation. Single sided designs allow easy access and the heat of a fire to be reflected into the shelter, whilst full roofed designs have much better heat retention. As a general rule the roof should be at least a foot thick and opaque to bright sunlight. Artificial Bivouacs can be constructed using a variety of available materials from corrugated iron sheeting or plywood, to groundsheets or purpose made Hootchs (Bashas). Although these have the advantage of being speedy to erect and resource efficient they have relativley poor insulative properties and are relatively easily damaged by the myriad of sharp objects usually found in camp.
A hootchie (or Basha) is a simple tent, made from one or two sheets of waterproof fabric and some strong cord. Generally a Basha is made of RipStop Nylon with a re-enforced seam, eyelets and loops or tabs are located along all four sides of the sheet and across the two central lines of symmetry. Usually measuring 6 foot by 8 foot (although much larger sizes can be found) the Basha is an extremely versatile shelter that can be errected in many different ways to suit the particular conditions of the location. (The word also sometimes refers to a special type of bivouac sack.)
There are many different ways to put up a bivouac shelter. The most common method is use one bivouac sheet as the roof of the shelter and a second as the groundsheet. The 'roof' flysheet is suspended along in its ridge line by a cord tied between two trees which are a suitable distance apart. The four corners of the flysheet are then either pegged out or tied down to other trees. Care must be taken to leave a gap between the ground and the sheet to ensure that you can see out and that there is enough air flow to stop condensation.
Storm poles are often used - these are poles made of metal and are used to hold up bivouacs. They are normally extendable and raise the heights of the bivouac. They are often used by fishermen. Hikers often use their extendable Trekking poles for the same purpose.
When making camp in a tropical situation, where sleeping off the ground is desirable, it is a common practice to string up a hammock underneath the bivouac rather than use a groundsheet. scout-o-wiki:Biwak