Basements (if they have them), roof, attic, crawlspace, exterior, and all mechanicals are where all the unseen costs are not in the kitchen, bathroom, etc.

You tried getting a roofing job from Bob Prisco aka Bob Stevens, or you tried getting a roofing job from Elliott Taylor?

Flooring, Drywall, refinish basement, roof, gutters, tuck point around house, and one full bathroom gut all had to be completed. 

I believe right now it is although prices are going through the roof.

You asked about buying older properties and the biggest issues I have found is that roofs need to be replaced, HVAC needs servicing/replaced, and sometimes there are foundational issues (not super common). 

This is a typical roof drain.

What is a storm rips through and trashes the roof, BUT the condo project does not have enough insurance coverage to fix it, the value of the all the units in the project just went down. or, even if they are able to fix it but  the coverage premium doubles so the HOA has to double the monthly HOA dues but half the complex can not afford it? 

I live in Georgia and the hurricane destroyed the roof.

Until you spend 20k on paint and some new kitchen appliances, but the roof and foundation are still shot and the 100k ARV is more like 70k in reality.

If a major expense comes about (i.e. roofing repair, hvac, etc) we would split that as well.