@Jeffrey Evans what you're really looking for from what I can tell is horizontal income streams.  

Horizontal income streams are your friend.     

That number only assumes horizontal addition, so adding an other floor would make the number higher.

Southern California resists this and is more orientated as a horizontal / automobile dependent city.There is probably not a crash on the horizon for your market.  

Definitely start small, with what is called "horizontal investing" - several multi-family buildings, up to 4 units.

Don't forget the horizontal development necessary: roads, sewer lines, electrical service, and data/internet running to each unit.  

Both methods are commonly used when a foundation company fixes a horizontal crack in a concrete basement wall.  

Once you figure out what you can build you figure out your ballpark cost per unit or totals for vertical construction, horizontal costs, holding costs, interest, commissions, closing costs, ect ect and an estimated sales price per unit or total. 

We are ready to break ground with horizontal construction today.

See language below along with pictures:"Horizontal cracking on East side of basement.