Lehmsteine (clay blocks) are unfired masonry units made from clay, sand, and natural fibres. They are typically used for non-load-bearing interior walls and partitions, though denser formats can serve in load-bearing applications. Because they are air-dried rather than kiln-fired, their production requires very little energy and results in a much lower embodied carbon footprint compared to conventional bricks or concrete blocks.
Clay blocks are vapour-permeable and hygroscopic, helping regulate indoor humidity and contributing to a balanced indoor climate. They also provide thermal mass, storing heat and releasing it gradually. At the end of their life, Lehmsteine can be broken down and fully recycled into new clay products or returned to the earth, making them a circular, non-toxic building material with long-term environmental benefits.
