Each side may add up to about $3000-4000 each. 

My logic is that maybe a pattern of new building permits in an area might indicate a hot market. 

Interesting  idea but I'm always leery of 100% mortgages...but im always on the conservative side of things.

Top/bottom duplexes are not preferred to side by side because of noise, water damage, access.

I invest in southside flips mostly and looking for a cheap personal living situation in one of the nice north side neighborhoods, since coach houses are sometimes pretty heavily beaten up in the nicer neighborhoods it could be a project I could afford and take off the hands of someone while giving me prime location, then eventually a rental single family unit type property when I move into something bigger. 

Also as a side note, I'd always recommend doing a conventional instead of FHA if you can.

Right now the market is still hot.

I am a newly licensed Real Estate agent in the state of Iowa. I am working under the Keller Williams Realty Greater Quad Cities office. I look forward to connecting with other agents as well in addition to investors. ...

Oh yeah, we also renovated every square inch, including a new roof, HVAC, hot water heater, windows, waterproofed the basement, What was the outcome?

I would recommend you leave yourself some room in the numbers when you go to refinance out of the HML and have some extra cash on the side just in case.