@Michael C Williams is correct in that many places in San Francisco convert the ground level garage and storage areas into legal dwelling spaces (ADUs), but IMHO these are not the best properties to hold long term as it changes the classification of a property from a SFH to a multi unit.

By 2021 I had 33 rentals and 135 storage units.Acceleration (for me) required a shift in my mindset, money, and a good market. 

We focus on self storage, MF, student housing, mineral rights, government lease, industrial, and avoid retail and office.

They owe money to you for  back rent, court costs, up to the date of when you get possession of apartment per the court, and maybe storage costs if they left personal belongings.. list it all in the security deposit statement.You'll need to file a separate court action in small claims court but I'd try you might get lucky, worst that will happen is they don't show, it cost you probably 50 bucks to file.

Comml- Self Storage, because that's what I do. 

Self storage in a warehouse this climate controlled.

Texas law does not address storage of security deposits so the landlord if free to do whatever they see fit. 

My question has to do with having some storage for us at the rental property.

Going to look at a 15 unit mobile home park tomorrow. 4/15 pads occupied (@ $235/mo), plus one storage unit rented @ $290/mo plus one farm house rented @425/mo.

While turning over a vacant rental property, I noticed that the lower storage pan in the fridge, along with the shelf support, was broken.