Of course not.

The problem will come when you want to change the status of the house to sell it.

If you want to sell it as a single family home (more valuable) you'll need to get the certificate of occupancy changed.

If you want to live in it as a single-family but resell as a multifamily, your buyer will wonder what you've done with the two extra kitchens, and will ask that you reinstall them before he/she buys.

Ali
Alison Rogers
author, "Diary of a Real Estate Rookie"
Insider Real Estate Tips with a Twist of Humor: http://tinyurl.com/2ag28z

Usually no. The answer lies in examining the building's Certificate of Occupancy (CO)

In my experience, you almost always need a permit, it's not about load bearing walls or electrical upgrades. if you're doing remodeling, they want to know what you plan. It's a good idea to simply go down to your local code enforcement department and ask and expect to pay a fee for the permit related to the cost of the improvements you plan to make.
This is a much better route than what could happen if you don't: Your neighbor gets annoyed with all the hammering, calls the code dept. on you, and you get a huge investigation fee on top of the original permit cost you should have paid to begin with! Good luck with your remodeling plans, sounds interesting!

Brendan Murphy
Broker, CRS, GRI, ePro
Raving Real Estate
Laramie, WY 82070

Gail, Thanks for your answer. A follow up question -- do I only need permits if I am changing internal structural elements? E.g., if my engineer and architect come up with plans that don't involve touching any load bearing walls or beams, may I still need a permit?

There is nothing to stop you from a single family occupying a a multi-family dwelling, no matter how many units there are.