Rooming House Lease Advice Needed

[Scott Donahue]

In the process of transitioning from SFR to Mixed Use Commercial! Just purchased a value add 16 unit rooming house with 3 commercial spaces. The property has about $50k in deferred maintenance, but surprisingly, a 90% occupancy rate. None of the tenants have leases in place and all are paying below market rents, in cash, to an onsite property manager who stays for free. I plan on SLOWLY raising rents to slightly below market rates as the rooms turn over. Same with the commercial space. My question is on the rooming rooms (yes, I know it's redundant): Does anyone have experience with leases in medium (if that is a thing) term rentals? Most of the tenants are week to week, but have lived in the property for years. I would like to get leases in place for numerous reasons, but I've never heard of such a thing for week to week renters. Any help here would be outstanding!