Recent development trends largely look for possibilities of a wider use of natural materials and local resources. In this perspective, the use of organic rich lake sediment – sapropel – as a binding material in line with other environmentally friendly filling materials can be considered as a challenge. Sapropel itself is a valuable resource with multiple areas of application, for example, medicine, veterinary, agriculture, livestock farming, balneology, cosmetic applications, construction, and its application options have been widely studied in the 20th century in the Baltic countries, Ukraine and Russia. Birch wood fibre and sanding dust, hemp shives, ‘Aerosil’ are used as a filler and three types of sapropel are used as a binder in making composites. After material preparation and curing, physical and mechanical properties - density, thermal conductivity, compressive and flexural strength, were determined and compared to the data in the literature, and the opportunities to use them in the ecological construction were considered. The obtained results give insight into possibilities to use sapropel as a raw material, which can be considered as prospective material for construction materials and design products.