Garage firewall

I have searched for information regarding the installation of a firewall between the garage and living area. I have inspected a home built in 1900 which an attached garage was added onto. The wall is covered with chip board to the bottom of the garage rafters. Above the rafters is the roof of the existing structure - minus shigles. NONE of the local city or county folks will give me a straight answer. In my mind this is not a legal firewall. The property is located in NE Nebraska. Anyone have any thoughts?

often seen on older properties
lucky to see anything on the garage separation

regardless of age or location
the best an inspector can do is note the deficiency, advise safety enhancement upgrade to current standards and move on, it’s the purchasers decision to follow the advice or not

were builders even using gypsum board in your area back then?

Ditto what Barry said… report, recommend, move on.