Now add inflationary pressure in one direction, and recessionary wage suppression in the other. 

In large part much of this information has been suppressed, by design.

But I doubt he’s suppressing 50% of his cost.

Demand is suppressed by the dearth of lending.

There is no active fire suppression system that is cheaper then good old fashioned water.

I am nervous about things like not being up to code or having to install fire suppressant systems...

The contractor commented that while the elevators and sprinklers are grandfathered in, if I had to extend them in any way the grandfathering would be lost and I would have to replace them all with new code-compliant systems.If you got a new tenant that was perfect but required additional fire suppression, would you want to replace the whole system for them or would you let the space go vacant?

There are "poor" landlords and slumlords in all sizes of properties.That said, in our experience, there is the no-mans-land of small multi-unit properties (5 - 20 units, say) where financing will be commercial and, if not a converted house, the property will have the commercial systems one expects to find in larger buildings (fire alarm and suppression, security doors, common boiler, common laundry, etc).  

@Nick SabatWe still have to manually test smoke detectors twice a year (insurance purposes), but in bigger buildings are experimenting with being able to tie into the alarm and suppression system to get alerts and check status.We may have a deep retrofit renovation ahead of us this summer (depends how things go at auction in a couple of weeks and our velocity with all the other projects) where I plan to install a "smart" panel which will allow us to remotely monitor and control individual circuits.

Being a person who finds suppression of violence a tedious daily annoyance- these issue you brought up ranks just under waiting for my daughters captor for things to do.