Where can I find the California building codes for firewalls between town homes? While moving my daughter's new bed upstairs, I put a hole within...

While moving my daughter's new bed upstairs, I put a hole within the drywall, and while I was replacing the drywall, I found that in that is no firewall separating my town home from my neighbors townhome. (A firewall is a wall made of brick or cinderblock that is used as a buffer to protect homes from fire.) I would resembling to find out if they are manditory in San Diego, CA, because they are fund home.... Where can I find out?
Customer used diffuser on glasstop to simmer soup....
Answers:    Firewalls can also be made with 5/8" Firerock, fire resistant Drywall.
Yes the building code does require a firewall between unit.