Fire-rated assemblies are construction elements designed to resist the spread of fire and smoke for a specified period. These assemblies include walls, floors, and ceilings that are built using materials that can withstand high temperatures, helping to protect occupants and property during a fire. The effectiveness of fire-rated assemblies is measured in hours, indicating how long they can maintain their integrity under fire conditions. Common materials used in these assemblies include gypsum board, concrete, and steel, which are often tested and certified to meet specific fire safety standards set by organizations like the National Fire Protection Association (NFPA).