The ratio thing doesn’t really work here but you can look into submetering the meter that is supplying the common area.Just a random thought, I’m not sure of your specific situation but say your common area has two lights both of which are fed from the unit 1 breaker box (2 dIfferent circuits).

I'm with you that these are deal breakers for me.

Updating that would be significantly more costly than say a home from 15 years ago that has the wire you need but code requiring that it needs to be updated to say gfi's/afci breakers.

It appears that, other than Mike's tip regarding audible noises from the floor, most major issues with the foundation can be spotted by a careful, naked-eye inspection.As a follow-up, do both of you (or anyone else that joins the thread subsequently) rule out properties at that point or consult first with an expert to see if the issue is a deal breaker? 

Its a 120V circuit.

I have a friend and client that was on the real estate guru circuit for many years.  

Typically two small appliance circuits in a kitchen plus one for the washing machine.

If I use a bank they will want first position - deal breaker for the seller.

Having one unit with a shower only I'm sure won't be a total deal breaker for future rentability.Good luck.

Right now have makeshift wood column providing additional supportElectrical - replace Federal Pacific equipment, replace fuse panels with circuit breaker panels, remove or disable any knob and tube wiringmove air conditioner so can inspect fire escapeschimney -Have a qualified chimney contractor service or repair the chimney(s) as required to assure long term function and safetyOld Roof - have roof contractor inspect and find out cost to replace as its oldSome floor tile in common halls is older 9 inch floor tile of a type commonly containing asbestos - do I need to be concerned?