This was 2015 so although it didn't cash flow, the other unit offset my mortgage by quite a bit.

You are hopefully getting good cash flow, appreciation, mortgage paydown and tax benefits.   

Many likely have coverage for their mortgage balance or from many years ago.

That will determine if you could sell it and use the money to buy a single family home or would need to take out a mortgage. 

It's the concept of buying the debt attached to the mortgage rather than buying the house. 

It is nearly impossible to follow NYC's requirements and run a proper housing business.

In 2007, my wife was in the mortgage business. 

However, it’s important to ensure that the deed is properly recorded with the county recorder’s office to make the transfer official.

In 1972 the 30 year mortgage interest rate was 7%.

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.