about multifamily valuation/comps

[Zack Ak]

Hi..

I am in NY area. I and my partner- we are currently looking at a property with a 2family structure on it. The property has the zoning to be build up to 7 floors...but we can not find any comps in the area for such a building, since most of the buildings are 2-3 families and some distant coops.  We would appreciate if you can suggest a few ways to value such a building...