**Appendix H**

Additional details about the calculation of Young's modulus and the analysis of the bending test data are described here. Throughout compression testing, the cross-sectional area of the specimen increases. To calculate the compressive stress, ASTM D2166/D2166M-13 states that the cross-sectional area of the specimen used in the equation should account for specimen deformation throughout the test [55]. The ASTM standard contains a formula to estimate the cross-sectional area of a specimen for a given load. This formula was used for one of the specimens that had an initial cross-sectional area of 42.19 cm<sup>2</sup> before the test. The formula estimated a cross-sectional of 168.76 cm<sup>2</sup> after 75% deformation. However, the measured cross-sectional area was 59.58 cm<sup>2</sup> after 75% deformation. Therefore, this formula was not used in the calculations of compressive stresses. Additional details about the calculation of Young's modulus and the analysis of the bending test data are described here. Throughout compression testing, the cross-sectional area of the specimen increases. To calculate the compressive stress, ASTM D2166/D2166M-13 states that the cross-sectional area of the specimen used in the equation should account for specimen deformation throughout the test [55]. The ASTM standard contains a formula to estimate the cross-sectional area of a specimen for a given load. This formula was used for one of the specimens that had an initial cross-sectional area of 42.19 cm2 before the test. The formula estimated a cross-sectional of 168.76 cm2 after 75% deformation. However, the measured cross-sectional area was 59.58 cm2 after 75% deformation. Therefore, this formula was not used in the calculations of compressive

In addition to the load-deflection data, the modulus of elasticity, maximum load, and flexure extension at maximum load were collected from the Instron. However, ASTM D1037-12 contains a specific formula to calculate the modulus of elasticity. The moduli from the Instron reading and the ASTM calculation were slightly different. The modulus calculated by the Instron was higher in most cases. Since the calculation used to find the modulus by the Instron is not known by the authors, the modulus of elasticity calculated from the ASTM standard was kept for data comparison. Following the standard, the slope of the straight-line portion of the load–deflection curve was calculated with a linear regression of the load–deflection curve between 10% and 40% of the maximum load. stresses. In addition to the load-deflection data, the modulus of elasticity, maximum load, and flexure extension at maximum load were collected from the Instron. However, ASTM D1037-12 contains a specific formula to calculate the modulus of elasticity. The moduli from the Instron reading and the ASTM calculation were slightly different. The modulus calculated by the Instron was higher in most cases. Since the calculation used to find the modulus by the Instron is not known by the authors, the modulus of elasticity calculated from the ASTM standard was kept for data comparison. Following the standard, the slope of the straight-line portion of the load–deflection curve was calculated with a linear regression of the load–deflection curve between 10% and 40% of the maximum

The figure below presents how the fracture offset from the center and fracture angle were measured for the analysis of the specimens after the bending tests. load. The figure below presents how the fracture offset from the center and fracture angle were measured for the analysis of the specimens after the bending tests.

**Figure A1.** This abstract diagram shows the measurements used to compare the fracture observed in each specimen under bending to the ideal scenario. A bending specimen is displayed from the top view. The failure of the specimen (i.e., fracture) is shown in blue, whereas the ideal failure scenario is shown as a green dashed line. The two broken halves of the specimens are measured (A, B, C, A′, B′, and C′) to find the location of the specimen's failure. The fracture offset from center (d) represents the distance between the middle of the ideal failure scenario (green point) and the middle of the actual failure location (blue point). The fracture angle is measured by comparing the axes of the ideal and actual failures (α). **Appendix I Figure A1.** This abstract diagram shows the measurements used to compare the fracture observed in each specimen under bending to the ideal scenario. A bending specimen is displayed from the top view. The failure of the specimen (i.e., fracture) is shown in blue, whereas the ideal failure scenario is shown as a green dashed line. The two broken halves of the specimens are measured (A, B, C, A0 , B0 , and C0 ) to find the location of the specimen's failure. The fracture offset from center (d) represents the distance between the middle of the ideal failure scenario (green point) and the middle of the actual failure location (blue point). The fracture angle is measured by comparing the axes of the ideal and actual failures (α).

The evolution of mycelium and contaminant growth in the first batch is briefly described here. During the growth process, the state of the panels placed was visually assessed in a see-through enclosure. Environments were kept closed to limit contamination. Eleven days after inoculation, small amounts of mycelial growth were observed on the specimens. However, grey and green spots, likely contaminants, were seen. Twenty-one days after inoculation, mycelium formed a thin mat over most of the visible specimens'
