Section 302 requires that buildings with more than one occupancy type be separated by fire-rated walls, floors, and doors based on the hazard levels of adjacent occupancies. Hazardous occupancies including laboratories, warehouses, and manufacturing areas require 1-hour to 4-hour separations from other occupancies depending on the specific hazard. Office occupancies require minimal separation from educational or business uses but need 1-hour separation from hazardous uses. Residential occupancies require 2-hour separation from commercial uses and 4-hour separation from hazardous occupancies. The fire-resistance rating is determined by identifying the most hazardous occupancy and requiring appropriate separation. Openings in separating walls must be protected with fire-rated doors. Ductwork crossing occupancy separations must include fire dampers. Sprinkler systems may be required in separated areas to reduce fire spread risk.