Research and its conclusions
The Samorost project is not based on visions, but on real, proven data. The mycocomposite has undergone a series of laboratory tests according to Czech and European standards, which tested its mechanical properties, behaviour when on fire and reaction to humidity and weather conditions.
The aim was to find out if mycelium-based material could realistically replace polystyrene and where its limits are.
The compressive strength is 1.96 kN at 10% deformation, or approximately 180 kPa. The material is more durable than both conventional and stabilized expanded polystyrene, but weaker than extruded polystyrene.
The bending tensile strength is comparable to cork. Mycocomposite is stronger than polystyrene, but is not designed for supporting structures, such as beams or girders.
The fragility, i.e. the internal cohesion of the material, is 100 kPa, which corresponds to façade polystyrene 70F.
Flame tests confirmed it was in class E. The material does not drip or spit out hot drops when burning, it smoulders slower than wood and provides a longer time to evacuate.
Thermal humidity behaviour and vapour permeability were also important areas. Tests in the climatic double chamber at UCEEB CTU proved that mycocomposite meets the standard requirements for thermal protection of buildings. Insulation that is 16 cm thick has a heat transfer coefficient of 0.3 W, which corresponds to the requirements for external walls. With a greater thickness, it is possible to achieve the standard of both a low-energy and passive building.
At the same time, we verified the weather resistance. Long-term exposure to outdoor conditions has shown that, without additional protection, mycocomposite is not suitable for direct use outdoors.
The conclusion of the research is clear. In most common applications, mycocomposite can replace polystyrene for insulation of perimeter walls, roofs, floors and interiors. It offers comparable or better technical parameters, improved fire behaviour and a major environmental advantage, is made from waste and is fully biodegradable.
In addition, we know exactly where its boundaries are. It is this combination of performance and clearly defined limits that moves Samorost from experiment to practice.
Mechanical properties
Compressive strength test
What was tested:
How much pressure can the material withstand before it begins to deform?
How the test was performed:
On a 10 cm cube, the pressure was gradually increased until it deformed by 10 percent. The compressive strength test was carried out at the Faculty of Civil Engineering CTU in Prague according to CSN EN 826.
What this means in practice:
To deform the mycocomposite cube by 1 cm, the press had to exert a force of 1.96 kN. This is equivalent to approximately 196 kg.
In other words, a person weighing 200 kilos could stand on a cube and the material would only deform a centimetre.
The result:
Mycocomposite is more durable than both conventional and stabilized expanded polystyrene. Only extruded polystyrene shows better results.
Bending tensile strength test
What was tested:
How the material behaves when a load is placed in the middle, i.e. whether it bends, cracks or springs.
How the test was performed:
A 4 × 4 × 16 cm beam was supported at both ends and gradually pressurized in the middle until it cracked. The bending tensile strength test was carried out at the Faculty of Civil Engineering CTU in Prague in accordance with the CSN EN 15534-1 +A1 standard.
What this means in practice:
This test simulates a situation where the material acts as a beam or girder.
Mycocomposite is stronger than polystyrene and its properties are comparable to cork. However, it is not intended for supporting beams or structures that must bear a heavy load. It is less strong than wooden materials. Thanks to its low weight, however, it is self-supporting, i.e. it holds its shape without support.
Fragility test
What was tested:
How strongly the material holds together inside. How much force is needed for the material to tear.
How the test was performed:
A 42 x 400 x 600 mm plate was loaded to determine how much force was needed for a “tear” inside the structure.
What this means in practice:
Mycocomposite burns, as does wood, but wood burns easily and quickly, while mycocomposite gradually smoulders and loses its structural integrity more slowly.
Unlike polystyrene, it does not drip or spit out hot drops. This is a fundamental difference in terms of fire safety. This allows more time and less risk of secondary fire spreading during evacuation.
Thermal-humidity behaviour test and vapour permeability
What was tested:
How the material behaves in real operation of a building, i.e. when it is warm and humid inside and there is frost, rain or increased humidity outside.
The test focused on three fundamental questions:
- how well the material thermally insulates;
- whether moisture condenses in it;
- how it reacts to long-term temperature differences between the interior and exterior.
How the test was performed:
Testing was carried out in accordance with the CSN 730540-2:2011 standard at the UCEEB CTU in Prague.
On one side of the wall, the “indoor environment” was set at 22 °C and normal humidity.
On the other side there was an outdoor climate.
The test was carried out gradually:
- it started at 22 °C and 50% relative humidity;
- the outdoor area was then cooled to −3 °C at 70% humidity;
- subsequently, the temperature dropped to −15 °C.
Such conditions correspond to the winter season in Central Europe.
Two structural wall compositions were tested. One with a chitosan finish on the panels, the other with a classic diffusion-open composition similar to wooden buildings, i.e. paper-based insulation and a jute vapour brake. The walls were exposed to these conditions for a month.
What this means in practice:
The results of testing proved that mycocomposite is a fully functional insulation material suitable for Czech climatic conditions. With a thickness of 16 cm, it reaches a heat transfer coefficient of 0.3 W/m²K, the value required by the standard for ordinary houses. At a thickness of 24 cm it corresponds to the standard of a low-energy house and at 27 to 41 cm it enables the parameters of a passive building with minimal heating costs to be achieved.
The material thus functions as fully-fledged thermal insulation in Czech climatic conditions.
Thermal-humidity behaviour test and vapour permeability
What was tested:
How the material reacts to the long-term effects of rain, humidity and temperature changes.
How the test was performed:
The panels were exposed to the outdoor environment without a protective layer for two months. We conducted the testing using our own experiment.
What this means in practice:
Without additional protection, mycocomposite is not suitable for direct use outdoors. After two months of exposure to climatic conditions, there was a surface attack by fungi and mould. There was no deep structural damage, but a protective layer is required for outdoor applications.
Safety for health
An expert opinion by RNDr. Jaroslav Klán, CSc., confirms that mycocomposite is not toxic to humans or animals.
The material does not release harmful substances or spores causing allergies and is not detrimental to health during production and use.
Laboratory tests have shown that mycocomposite:
- has excellent insulating properties;
- is self-supporting and lightweight, yet strong;
- has a naturally hydrophobic surface;
- exhibits more favorable behavior during a fire than conventional polystyrene, does not drip or spit out hot drops;
- is made from waste raw materials and is fully degradable;
- is harmless to health;
- has an original and aesthetically valuable surface structure.