Permitting plans, can I do them myself?

[Ashton Sharp]

I'm doing a two car garage conversion into an apartment, all of the zoning is there, I'm wondering if I have to hire a contractor or an engineer/architect to do all of the drawings i.e. Site plan, energy plan, floor plan, structural plan, and so forth. Is there a place I can go to get any of these that might already exist such as a structural plan? Any help is appreciated!