I've done it for single-family residential.

Quote from @Chris Seveney: Quote from @Alejandro Galaviz: Quote from @Don Konipol: There has always been many questions as to if one needs to be licensed to engage in COMMERCIAL mortgage brokering/origination or RESIDENTIAL INVESTMENT property mortgages.  

Quote from @Jaycee Greene: Quote from @Mark Daniels: I know in residential lending you can get a HELOC to borrow a down payment to buy another property.

My wife and want to move away from the traditional ownership of small residential properties.

@Sushil Gupta    Fannie/Freddie will only allow you to have 10 financed residential properties IF looking to finance  a new investment property.

Residential buyers have been paying retail prices despite rising interest rates. 

Consult eviction attorney regarding commercial; I'm specifically a residential PM and commercial usually has different rules because of the nature of the investment and occupancy (tenant doesn't [usually] live there)

In the nine situations specified, lenders may not enforce due-on-sale provisions in real property loans “secured by a lien on residential real property containing less than five dwelling units, including a lien on the stock allocated to a dwelling unit in a cooperative housing corporation, or on a residential manufactured home.”The reason the act was passed was that with mortgage rates approached 20% in 1981 - 1982 certain state legislatures were passing bills that declared due on sale clauses invalid.  

. · New residential units cannot exceed 1,750 square feet each. // Setbacks & Spacing · A minimum 4-foot setback is required from side and rear property lines. // Tenant Protection & Restrictions · If a home on the lot had tenants in the past 5 years, SB-684 still applies, but you cannot demolish or alter the existing structure.

Since you're owner-occupying the duplex, most lenders won’t allow you to put the property into an LLC while you have a residential mortgage, as it could violate loan terms.