On-site self storage for multifamily

[Oliver Sparks]

I know that some people use different algorithms and demographic research to tell whether or not certain locations would be good for self-storage.  However, I'm curious to know whether multi-family investors have any luck building on-site self storage units even when there are other storage units in the area (less than a half-mile away).  I'm about to close on a multi-family property that has room to build some storage units across the parking lot, but I'm unsure how to know how justifiable of an investment this would be.  In this case it would be weighing the convenience factor of it being nearby, vs. there being some just down the road.  Thoughts?