Monty Chong-Walden

There are more and more videos on hempcrete building all the time out there. Here is a place to start looking at a few:
https://hempcretewalls.com/videos/
Where are you based? You are not likely to find any manufactured products for either hempcrete or mycelium in North America. And, neither of these are structural, so you need to figure out the structural part too. There are more and more suppliers of materials around, so you just have to figure out how to get the materials and the labour to do it. It is definitely worth it to build with hempcrete.

Brian Knight,
The R-value of hempcrete is around R2/inch, and sometimes higher, but there is also the thermal mass and heat capacity which leads to a 12 hour or more phase change of temps from outside to inside and vice-versa. The hempcrete builders in England say that their homes will stay at a pretty steady 65F whether hot or cold outside with a 12" thick wall, once the roof, windows and doors are in.
As for air transpiration, the right hempcrete will be dense enough to slow that down, and with s good render on at least one side, it acts as an air barrier and traps the pockets of air inside. It works very well when done with the right details.

The lime binder is key to having a long lasting building, as the Romans have proven with their buildings that can be 2000 years old. The hemp Hurd is good but it can many different bioaggregates, like rice husk, wood, artichoke stalk even! We need to incorporate much more building and many more products to make monolithic biocomposite buildings out of waste forestry and agricultural resources, and create durable, healthy, energy-effixient and carbon sequestering homes.

It continues to gain strength and harden over time (if done correctly) as it slowly absorbs more CO2 from the air. Senini Tecnocanapa in Italy has an unfinished demonstration wall at their plant that has been sitting in the elements for 7 years and it is as hard as stone! There is a little erosion on the top of the wall, but the rest of it is solid and flat. This material is based off historic materials like cob or Adobe that have been shown to stand the tests of time.

To have a decently solid hempcrete wall, it needs to be about 340kg/m3 (21.2 lbs/ft3). To have a decent insulation it needs to be at least 6" thick, so then you are at 10.6 lbs/ft2, which is a little heavy for a  THOW and only about R-14. Maybe better to think about using hemp batt or wood fibre insulation instead.