Soil has been traditionally used to cover roofs in different parts of the world. In arid climates, either very hot or very cold, it regulates the inside temperature, due to heavy thermal mass. In Scandinavia, the earth to cover roofs was taken with grass, so as to hold the soil and give cohesion to it through their roots. This method gave also more thermal mass and allowed the inside temperature to be more even.

In Nordic countries but also in the Himalayas regions, waterproofing was done long ago with the bark of birch trees. The bark peeled from the tree was very thin and I was applied in several layers to get a waterproof effect. Nowadays, waterproofing is done with PVC or bitumen sheets.

Green roofs are today a modern development of the technique of covered earth. Green roofs, also known as vegetated roof covers or eco-roofs are multi-beneficial structural components that help to mitigate the effects of urbanization on water quality by filtering, absorbing or detaining rainfall.