What entities must get involved when building a new home or modifying the exterior of a home?
Code making bodies refer to them as the "Authority Having Jurisdiction" and they could be municipal, county or state depending on where you live.

I had to go to one entity to get a well and septic permit, another one to get an address for my property and a third to get my building permits.

It is an arduous process but is required to ensure safe building methods are used.

Good luck!