When does a vehicle become subject to building codes?

[mark handler]

Thanks Mark, but that thread appeared to be more about a modular like this, that is towed to a site and placed on jacks for longer term (>180 days) use:
View attachment 9588

My question is, would you require the same kind of permit and plan check for a short term trailer, like this movie location restroom vehicle?
View attachment 9589

IMPO
You would not Enforce what is in the trailer. You would enforce the Utility connections.
Side Note, there is no Accessibility, for the Disabled on Photo provided.
Unless the ramp is a part of the Trailer, the ramp needs to be permitted.

 

[mark handler]

I believe the city building official is not applying that code section properly
3103.1 General

The provisions of Sections 3103.1 through 3103.4 shall apply to structures erected for a period of less than 180 days....

3103.1 "... Shall apply to structures erected for a period of less than 180 days...."
IMPO, You are not erecting the Prefab trailer.