Been following your thread and I must say that you have taken on a big project, but one that will be highly satisfying! Thanks for the details on the thickened perimeter, but wondering if those dimensions are a factor of your local frost depth, building size/height, both, other factors? I like this approach as an alternative to a pole building approach or traditional footing and frost wall method. I'll have my own outbuilding project coming up in another year or so and am getting great ideas from your project and others here on TBN!
The other thing I was wondering about was the channel that you formed in along the edge where the SIP wall was set. What's the purpose for this channel?
Thanks for documenting your project and I love all the pics! Great Job.