@Justin Browne Hi Justin. I am a Developer in Nashville and your question is a great one. Building 2 houses on 1 lot in the city is the best (and sometimes only) way to maximize returns. That said here are a few things to remember:
1. Zoning is key. The lot must be zoned R6 or R8 or R10. The "R" stands for residential. The number following indicates the size the lot needs to be to build on. For instance, the most common type of this lot in the city is R6, which means you can put 2 homes on 1 lot but the lot needs to be 6,000 sq ft or more.
2. The size of the home depends on the size of the lot. The height of the house cannot exceed 1.5 times the width, which can be tricky when building narrow homes. Also remember that you have 5ft setbacks on each side of the home which also eats away building space. This is why the "attached HPR" is so popular.
I usually have my hands in something so if you have any more questions feel free to IM me.
