I live here and want a house in mountain somewhere but can never make the numbers work. 

Had my sister-in-law come live with is a little over a year in as a house hack.

Yes, sharing our actual costs,  we need more housing but also letting people get past some of the big unknowns.   

If you have just one long-term tenant in your house hack duplex, and you're taking a $30,000 guru course on making money from assisted living or storage facilities or on running a syndication - it is probably not deductible under Section 162. 

Because we are in house with our development deals I am not counting on someone else's ability to find a good development deal.

Over a decade ago a friend and I bought a house together.

Purchase price: $505,000 Cash invested: $55,000 Sold our first condo and used the equity as down payment and for a couple upgrades on this this single family primary residence / house hack.

I cannot see how build two, say, 1200 sq ft houses with two roofs, two foundations, presumable about 25-30% more windows and siding is going to be cheaper a duplex that might have a little extra fireblocking and soundproofing.Now, maybe your GC is thinking that detached homes tend to get higher rent than comparably sized and finished duplexes.  

They typically do not add value to the house, so when the buyers are looking at comparables, none of them sit there and say...well every other house sold for $200,000, but my gosh this one has solar panels....let's pay $240,000 for this one.Maybe one day, maybe someplace, but NOT today in NJ I expect.Only way I would even look at solar panels is if it is for your forever house, and you have enough land to install them on the ground, not on the roof....so maybe if you have 1-5 acres or more. 

He renovated a property for me in Dania Beach last year and is currently doing my friend's house in Fort Lauderdale.