Boost in value by turning duplex into triplex

[Chelsea Knapp]

I’m looking at a duplex that is somewhat unique and doesn’t seem too hard to add a 3rd unit to increase cash flow. The one unit has a walk up to the second floor that has a second full bath and a wet bar (sink, stove, fridge) so it already has the basics for an apartment along with a dining area. Those stairs would be easy to block off both units. The wet bar has a pretty decent island already. The building has 3 furnaces as well.

If zoning were possible to allow for the 3rd unit and appropriate updates were made how much value would it add if I were to refinance down the road. Obviously a lot is market dependent but in short I’m looking for people who have experience adding a unit to a duplex and seeing a change in value.