Do You Know About Your Walls?
Vol. 20 No. 6
Passive fire protection seldom receives the attention that active fire protection does until a disaster occurs. It's at this point where everyone asks were there firewalls in that building? Back in the early days of rubber tire warehouses and the textile industry, facilities were commonly divided by walls of various types. Even today walls are used in commercial buildings for various reasons. As was discussed in the September-October issue, preparation for fire emergencies can be the deciding factor between whether a fire is halted or allowed to burn the entire building to the ground. In this article we will explore the different types of walls, how to recognize them and what role they play in property conservation and life safety. This will assist the emergency responder as he develops the pre-emergency plan for a facility.
The walls, as described in this article, have a multitude of purposes. Being able to spot the differences between various types of walls is key in determining how long it's expected to last in a fire. This can be critical when the fixed fire protection systems have failed to control a fire or the site has no fixed fire protection. After making an assessment at the scene of a fire that has progressed beyond the capabilities of the automatic sprinkler system, the ability to know where to make a stand in a two million square foot warehouse fire can mean everything.
The term firewall is used quite often to describe a wall that may not have ever been designed and /or constructed to halt a fire's progress. If you are not equipped to understand the differences you could be placing yourself in harm's way during a fire. There have been multiple cases where a fire originated in a sprinklered building equipped with what most people would call firewalls yet the site still suffered a total loss.
The most commonly used wall that most people refer to as a firewall is in reality a fire barrier wall. NFPA 221 defines a fire barrier wall as a wall that is not a firewall, but it does have a fire resistance rating. For instance, a fire barrier wall, which may be a 3-hour concrete barrier wall, does not meet the standard required to be a true firewall. A true firewall typically will be freestanding (not tied into the building structure), parapeted (extended above the roof line) and be afforded "wing walls", end walls to prevent fire from wrapping around the end of the wall. The large openings on true firewalls will typically be afforded 2-3 hour fire doors. Penetrations in true firewalls will typically not be above 3ft from the floor.
There are several problems in regards to true firewalls. These issues should be on the mind of every emergency responder. These problems are lack of operating fire doors, firewall penetrations that have not been properly sealed to prevent the spread of fire through the wall, or totally unprotected openings. This is why not only should pre-emergency plans be developed, but should be revisited on a continuous basis especially in high hazard occupancies. It is not uncommon for facilities to remove walls and make economic decisions without contacting the fire department. What at one time was a true firewall can be something totally different in a year's time. The fire doors should be trip tested on an annual basis, penetrations reviewed and assessed, and the overall structural condition of the wall reviewed.
Some walls are in reality meant to be partitions and are used for the control of smoke as indicated in NFPA 101 and in NFPA 5000. Also, these walls may be intended to allow a certain amount of time for escape and minimal long-term protection from fire. These walls are commonly constructed, if the environment allows, from gypsum board on steel studs.
Fire barrier walls are the most commonly found wall. These walls, are intended to be used in conjunction with the overhead sprinkler system to halt a fire's progress. To be able to identify a fire barrier wall is relatively straightforward. This wall has some of the structural characteristics of a true firewall. However, it will not be free standing, usually has only one 3 hour rated fire door on a large opening, will not be parapeted and could have multiple penetrations all along the wall.
Major property insurance companies use firewalls to estimate a maximum foreseeable loss (MFL) which assists them in knowing how much loss exposure they have in a given fire area. Other types of walls (barriers and partitions) are seldom considered by major insurance companies as having the ability to truly compartmentalize fires in regards to having the ability to halt a fire. This is typical of the insurance industry, which tends to be very conservative in regards to loss estimates.
If you need further guidance on differences between firewalls, fire barrier walls and partitions there is a considerable amount of information in the NFPA Handbook and NFPA 221, or contact this author. o
Jeffrey R. Roberts, CFPS, is a Senior Loss Prevention Consultant with GE Global Asset Protection