The DIY Net Zero ADU

With a modicum of construction skills you and one or two friends can have a very high quality, durable, and energy efficient shell that meets local U.S. codes for your area.  Using normal hand held carpentry and construction tools (no cranes, forklifts, or heavy machinery) you can assemble a 320 square foot shell in just a few days.  The addition of exterior and interior finishes, and if you choose, a bath, and/or kitchen, can then be completed at your own pace by having a "dried in" space to work in but it will still much faster than traditional building techniques. You should be able to easily complete a basic unit (no kitchen or bath) in less than 12* days with two people.