Was it ever explained how the Ropers came about to becoming the apartment building owners and landlords in the first place? The Ropers are not portrayed as very wealthy people so I really wonder how they managed to buy or build the apartment building. We also know that Mr. Roper is dirt cheap, so an apartment building doesn't appear to be like something that he would buy.

In the case of Mr. Furley, it's easy to explain because the real owner was his brother Bart who is portrayed as a wealthy businessman. In his own admission in the episode where Jack failed his cooking exam, Mr. Furley stated that he has never achieved anything in life and has never been successful.

Other than the fact that he was married, I don't sense any major difference between Roper and Furley. So I wonder if perhaps the apartment building was a result of some kind of inheritance.

I think that Mr Roper worked his whole life and used his retirement money to buy apartment buildings.

There is a good chance he had a rather large bank lone and, and was just getting a decent amount more in rent than he had to pay the bank every month.

What I dont know, is how Roper made a living in The Ropers, because I was pretty sure that he wasnt the landlord there (giving as the neighbor looked down on them)

if you recall in the episode when the relestate lady handed roper a check for x amount of dollars there was no mention of any outstanding debt or loan. he simply put the $ into his new home that he bought on the ropers.