The heat transfer properties of Mycelium boards were tested using the hot box method. The hot box method was employed to understand how the material would perform in a wider variety of applications than the previously employed guarded plate method, specifically how the material would perform in domestic thermal insulation applications. In addition to testing the material in boards, as it was manufactured, wall sections were constructed with studs to simulate installation in a home. Moist air movement was found to be a primary mode of heat transfer though the material and tests were conducted both with and without impermeable plastic sheets to understand this effect. Both the mCore material, which has an aspen shavings substrate, and the GIY -grow it yourself- material, which has a hemp chip substrate, were tested, with the GIY material being grown in house. Both materials have similar amounts of mycelium by mass, mycelium being the roots of mushrooms that are grown to bind the substrate material together like glue, forming a material similar to a very loose particle board. All mycelium products were provided by Ecovative.