First Day Cottages are kind of a different look, though. I'm not real informed about construction, so I could be wrong about the following, but this is my understanding of their construction. The structure is a kind of modified post and beam, but made of built-up dimensional lumber. David Howard, the architect/owner, invented the process. The sheathing wood is then applied to the exterior, leaving it exposed to the interior walls. The wiring is done from the exterior. No sheetrock is necessary. It's also a process that leaves fewer spaces for air leaks, so it's touted as wasting much less fuel for heating. The interior look is almost rustic, but some people choose to sheetrock in some spaces for a more formal look. Much different from any modular I've ever seen.
Since I detest trends and fads, especially those coming from HGTV stars who think they invented something because they use an idea ad nauseum, I cringe to say the following. But here it is. The look is pretty much like shiplap walls, although I'm not certain whether the actual joints in the sheathing are shiplap. What I do know is First Day Cottage has been doing it since long before a certain overexposed HGTV star has.