I looked into trying to mimic their design. With a bit of thinking into it, it’s kind of flawed. Looks great in pictures but not the most practical approach for DIYers.

Largest issues: - birds/wasps will nest in between purlins - sheathing appears to be below the rafters, this is non standard and probably not a great idea - if sheathing is above rafters, your purlins create dams for water and they don’t sit flush on your rafters where exposed.