I found the information on my city's website, under codes and regulations.

If you want to do larger deal, check out Section 42 of the Code with a 401C3

To become a member, you must pledge to a strict Code of Ethics and Standards of Practice. 7.

My friend invests in C class properties in the zip code of 44310, that rent fast and I believe rents are good based on what I've learned from BP.I'm looking to partner with my friend and start off small to build the business/iron out the quirks.  

I only use foam in high-end houses and when it's required to meet energy codes (for example, a house I just built in Georgia, the roof was framed with 2x4s instead of 2x6s, and the only way to get the required R-30 was to use spray foam).

Even Though (crawl space vents) are still a code requirement in most areas, I don't believe they are the way to go. 

Did you find that there were any unique obstacles to building modular homes other than the obvious building code, zoning etc. that you encountered in SoCal that you wouldn't elsewhere?

So many glitches in bad code these days.

Call code enforcement. 

@Keith Nelson the answer to your question lies with answering two more questions: (1) how much do you know about taxation in relation to rental real estate; and (2) how much time are you willing to put into researching the tax code to ensure your return is compliant with the regs?