Zoning alone does not make a property a two-unit. What actually exists on the ground, and whether each unit can legally function as a dwelling, is what decides it. Jeb's read holds up in practice: a property with two real dwellings on one lot is a two-unit even without an R2 label, and an R2-zoned lot with a single structure is still a one-unit property. For conforming purposes, Fannie Mae and Freddie Mac look at the property's actual characteristics, assessed through the appraisal's highest and best use analysis: separate utility meters, a unique address for each unit, and whether each unit can be legally rented. Zoning still matters as a floor. The two-unit use has to be legal (or legal non-conforming) for the property to be eligible, and legal rentability itself flows from zoning. So R2 zoning plus two legitimate dwellings generally gets you there, while the zoning label by itself does not carry the day. Where it gets genuinely murky is a separately built structure like a detached ADU. Whether that counts as a second unit or as a one-unit property with an ADU depends heavily on how the appraiser writes up the property and how title is recorded, and different files can come out differently. Agency guidance on ADUs keeps evolving, so if you are looking at a specific property, sort out how it will be classified before you write the offer. That is the kind of thing we dig into on the free Roadmap conversation (about 20 minutes).