“Birch bark has been used in Finland for centuries as a construction material and as material for making small objects like baskets and shoes. One of birch bark’s features is good thermal insulation. The surface is water repellent and it can be gently washed with water. Some components of birch bark also protect it from decomposing.
Finnish architects Teija Losoi, Anne Varsamäki and Ilari Pirttilahti used the technique to build a lightweight sauna – basically a huge traditional birch bark basket turned upside down. The light walls are supported by a wooden structure that is hidden inside two layers of braided birch bark.…”