I've built several single family homes and duplexes but nothing bigger. I've got a multi-family site available that is zoned for up to 18 units per acre. First unit at 6,000 each, additional at 2,200 square feet. So 8 units would need 21,400 SF. If I build two 4-plexs (townhouse style) per 21,400 SF, I don't need to have a sprinkler system. I would build 2 bed/1.5 baths or 3 bed/2 baths. These would be rental units so the finishing would be pretty basic. Would building one 8-plex with a sprinkler system be cheaper than building two 4-plexes with no sprinklers? The 4-plexes have to be townhouse style, while the 8-plexes could be townhouse style or garden style. The townhouse style would be 2 or 3 beds and the garden style can be 1, 2 or 3 beds.

I could also go bigger and build 16, 20, 24, etc. units per building. 16 units will require 39,000 SF of land. How much cheaper per unit would it be compared to an 8 plex? How much cheaper per unit would be 24 units? Should I stick with 2 story buildings or go up to 3 stories?

8-plexes would be easier to sell in the future since more buyers would be able to afford them.

What is the optimal number of units where I can maximize economies of scale?