Anyone heard of building with Hempcrete before?

Hempcrete acts as an insulator and moisture regulator better than concrete, and lacks the brittleness of concrete, meaning it doesn't need traditional expansion joints. It isn't all good though, it's compressive strength is 1/20th of residential concrete meaning it needs more framing and support for vertical load. If you're someone who is very much into the environment, it may be something you want to do as it does use less energy and water to create, and acts as a carbon sink, but will cost 10% more. Other issue is contractors may not be familiar with using it. Hemp-board and hemp-ply are stronger products (then non-hemp equivalents) and I'd prefer a contractor use those as there's not much difference to master than traditional.

Personally I am a fan of ICF foundations, as insulated concrete forms get really good insulation factor on both sides of the basement, easy water proofing and fast build structure -- steel spacers act as rebar reinforcement for a bonus.

Thanks, I asked my architect and he said the contractor would be using hemp but not hempcrete -exactly like you said, they contractor may not have much experience with using Hempcrete blocks. Hopefully the hemp however will do a similar job.