One of the main purposes of a fire protection system is to contain the fire, in the event that one should occur. In a building, there are various systems as well as structures in place to help minimize the spread of flames including firewalls and fire barriers. Although both structures help contain a fire while providing protection to the building occupants, there are important differences between a firewall and a fire barrier. According to the International Building Code (IBC) Chapter 7 and the National Fire Protection Association (NFPA) 221:
Firewalls – are exterior wall that extends continuously from the base of the building all the way to the roof. They are designed to remain standing even if the adjacent structure collapses. To do so, firewalls are built thicker than normal walls with significant structural stability under fire conditions. Sometimes buttresses or pilasters may also be required in order to provide adequate lateral stability. Firewalls will typically have a 3 to 4-hour fire-resistance rating.
Fire Barriers – are interior walls that extend from the floor‐to‐floor or floor‐to‐roof, including concealed and interstitial spaces. They are designed to sub‐divide portions of the building, and can be supported by structures, such as roofs, columns or floors. All support structures should have a fire-resistant rating no less than that of the fire barrier they support. Fire barriers restrict the initial flow of heat within the area of origin, which provides building occupants with adequate time to evacuate to safe areas. These walls will typically have a 2 to 3‐hour fire‐resistance rating.
So what is the difference between firewalls and fire barriers? Basically, firewalls are thick exterior walls with a higher fire-resistance rating, while fire barriers are interior walls with a lower fire-resistance rating. Both structures are important to a building’s fire protection system as they are designed to help contain the fire to one location as well as allowing occupants to evacuate safely. So making sure they are both properly maintained according to IBC and/or NFPA’s codes and standards is critical to the integrity of the building, and more importantly, the safety of those occupying it. This is why it is important to recognize the difference between firewalls and fire barriers. If any damage is done to the wall, no matter how insignificant it might seem, that hole or crack in the wall is enough to allow fire to pass through and ultimately put the lives of those in the building at risk.