Strengthening the interconnections between your tenants and local businesses sets the stage for a stronger community.

Most home inspectors are knowledgeable about the physical property but not as much about multi-family life safety codes (in particular fire protection such as sprinklers, interconnected smoke detectors, wall ratings, egress, etc.)You also might want to obligate the seller to obtain the CO.

the housing and stock market are interconnected in many ways.  

Do fire alarms need to be interconnected between all the apartments in a 3 unit building basically if apartment one sets the alarm off it rings in two and three?

The problem is that none were prepared for cold temps, even though Texas has had colder temps before, and all had issues at the same time, combined with Texas having an independent grid and not being able to bring electricity in from nearby states that weren’t experiencing lack of capacity issues, like Colorado (although @Joe Splitrock aptly pointed out an interconnected grid wouldn’t have solved the problem altogether, but it still seems to have been a contributing factor).

That's only some of the interconnectivity. 

When I started out I thought to myself "I'm going to invest in real estate" as if it's a linear path; this is a business of interconnected webs in 3D!

Electrical needs to be able to handle the load from both suites.smoke alarms through the house need to be interconnected as well as the carbon monoxide alarm.Fire protection between suites and a few ceiling height restrictions. 

These metrics are related and interconnected but are quite different. if you are new to finance and only looking at these things through the lens of someone with say one bank account and a small balance sheet, it's def harder to appreciate the gap between them. 

Attic living spaces can be deadly fire traps: https://wgntv.com/2019/01/30/2-people-killed-in-so...Aside from zoning please make sure that the smoke and CO detectors are interconnected with those in the spaces below and that there is an alternate way out of the space in the event of a fire.