It was meant (I guess) as a DIY project and really it's a shed so the process is similar and the 100 square foot print is usually the largest structure you can build (in a lot of jurisdictions) without a permit/inspections/code.
I mean, just because you're technically exempt doesn't mean that building codes don't matter. It's still generally a pretty good starting point for how to build a safe structure that you shouldn't deviate from just for the heck of it.
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It was meant (I guess) as a DIY project and really it's a shed so the process is similar and the 100 square foot print is usually the largest structure you can build (in a lot of jurisdictions) without a permit/inspections/code.