As an example, my neighbor added a second story to her home and the contractor gave her an estimate that she agreed to. 

I second the others here - look into adding a CPA to your team.

@Luke Spencer I am not on the management side but I can tell you it took 2+ years to fill 300 units at one of our facilities and the other just hit 300 units in 12/13 months so it really depends on the demographics, and local housing market trend, the more people moving in and out the higher the demand for storage.I think if you're looking at a saturated market then the upfront cash to turn the warehouse into self storage is not a good idea but then again, maybe those operators are on back roads ( low visibility ) and don't push google ads well.

I added value to this property by preserving its original architectural features while modernizing the interior.

What an investor gives up though is tax bene's and the chance ( well at least proforma wise) that you bought at X cap rate and can sell at Y cap rate and there is a big profit that is added on to your returns. 

Direct mail, SMS, door knocking, Facebook ads?"

But I will be honest, the rentals I have been added the last 2 years here in DFW have negative cashflowed.

A client of mine in Maryland added smart home features to their rentals and boosted rents by 12% with minimal investment.

I have yet to have one late charge added to a tenant.   

But, I'd like to focus only on value-adding renovations (for rentals of course).