They bought an apartment complex in 2014 with an intent of buying another property next door, demolishing both and building something new.

Go to China, visit the tens (I think less than 100) of ghost towns that were built with all the complexes and high rises, and see that about 100 people live in the town.

Plumbers have equipment that is much more heavy-duty than what we own ourselves and are experts in rooting out plumbing lines and ensuring drains flow freely.Electrician - While we do quite a bit of electrical work ourselves, it is important to have an electrician available for more complex work, such as upgrading an electrical box or replacing wiring.Carpet Sales and Installation - Every property we have ever owned has received new carpet at some point during our ownership. 

REO or HUD transactions ad another level of complexity and require their own paperwork, which is extra extensive and hard to understand if you lack the background. 

Self storage is pretty saturated here..My experience has been 4 plexes cost a little more per ft to build than the larger complexes but they command a little more rent.

I then look at the cash on cash return because I think it is a more solid number and more accurate to calculate than an IRR or something more complex with assumptions such as appreciation, etc. 

No property tax issues with common elements, no complex hazard insurance policy to deal with, no common area maintenance issues to deal with.  

Large luxury apartment complexes have been built over the years around the area meaning the rental business is increasing.

The whole process has felt pretty complex to me, but this seems like a big hurdle has been overcome.  

This example is not the only example, but it is the most complex one...which is why I used it.A business loan, personal loan, etc...are other examples of them.