Cost and availability of materials are pretty key considerations.
Also weight if you don't have mechanical lifting equipment.
You can get corrugated sheeting down to 0.1mm thick before they galvanize it.
Very light weight and relatively cheap from the far east. You can see it used in W Africa a lot.
Probably worth thinking about shelters in a couple of categories here -
-Pre fabricated components that fit to make a shelter (eg an existing tent)
- A design or idea that can be adapted for use with what is available on site.
(eg a plan for shelter using poles and a tensile sheeting material)
Cheers
FW
