Did you know that clay can also be used to create a lightweight, thermally insulating building material? Light clay is a composite material made from clay and various organic fibres, such as straw, hemp shives, or reeds. The fibres reduce the overall density of the material, while the clay binder helps regulate indoor humidity and keeps the fibres dry. The result is a breathable, low-carbon, and insulating material that is particularly suitable for infill structures and building envelopes, and can also function as additional insulation.
Light clay always requires a separate load-bearing (typically timber) frame. It can be compacted on site between formwork within the structural frame or prefabricated into elements and blocks of different sizes. On the interior side, light clay can be finished with clay plaster, resulting in an excellent hygrothermal wall assembly. On the exterior side, a thick wind protection layer is recommended.
The course takes place at the Fiskars Circular House – an experimental environment for building techniques and materials currently under development, where Aalto University’s Wood Construction Experimental House (relocated from Otaniemi) and a straw bale garage are also located.
During the course, we will combine hands-on work with a short theoretical introduction:
– The material principles of light clay and fibre–clay interactions
– Properties of different fibre materials
– Optimisation of mix proportions for insulation performance and material stability
– Preparation, mixing techniques, and testing of light clay
– Formwork methods and layer-by-layer compaction
In the course, we will construct both a site-compacted light clay wall and light clay blocks.
The course is led by Johanna Hyrkäs: architect, professional clay builder, and researcher in clay construction at Aalto University.
Address: Isokiskontie 16, 10470 Fiskars