Spruce's advice is good.
In most cases, replacing electrical, plumbing, insulation, or even wall surface (plaster/sheetrock) doesn't require submitting a comprehensive plan (a sketch will do); you'll just have to make sure it's "to code" before each phase of inspection.
However, any structural changes -- removing and adding walls, moving or changing the sizes of doors or windows -- may require submitting plans that have been reviewed by a structural engineer.
Remember that there will be several required inspections including but not limited to: rough mechanical (including plumbing, electrical, HVAC); structural; insulation; wallboard nailing (before taping/mudding!); final mechanical; final inspection. Any violations noted during an inspection must be corrected (and possibly reinspected) before work can progress. After a successful final inspection you will be issued an "occupancy permit" -- this is an official document that informs future buyers or tenants that the work was completed satisfactorily according to code.
The above inspections must be done in phases as the job progresses. For example, you can't do a rough plumbing inspection after the sheetrock is up. And you can't do a structural inspection before the plumbing, wiring, and HVAC are complete; the inspector wants to see that the structure hasn't been compromised by the other trades. In many areas you'll have to call different departments/inspectors depending on the system being inspected.
Last edited by Fencepost; 09-21-2011 at 01:32 PM.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.