How to Comp Multi Family MFR

[Mya Toohey]

I have a property that I am running a CMA on, and theres nothing comparable to what the finished product would be. It is a duplex that would have an addition done on top with the layout mirrored. Each unit is a 1/1, around 500 SF, and there are only duplexes in the immediate area, whereas I would be a fourplex. The duplexes in the area are 1700-2000 SF roughly between the 2 units. How would I find my ARV in this situation? Thanks!