Caution needed with strip mall fires


By Capt. Charles Bailey
Montgomery County (Md.) Fire and Rescue Service
Founder of TinHelmet.com


Photo Tod Parker/PhotoTac.com
Firefighters tackle a strip mall fire in Indianapolis in June.

Modern life presents firefighters with an amazing array of problems that include synthetic materials, engineered trusses and lightweight construction. Fires in strip malls have all of these features.

The average fire department is well equipped to manage a fire in one or two rooms of a residential structure. These are the fires that we fight on a daily basis, the fires that we train for and the fires that our SOPs are designed around.

But when a department is faced with a fire in a strip mall, the fight changes because the buildings are different, and they are not situations that we deal with on a regular basis.

This discussion hopes to highlight why strip mall fires are more dangerous than residential fires. It should also provide a framework for a shared understanding of the objectives and priorities with the hope that knowing these things will allow crews and commanders to operate more safely and effectively.
 
There are a few obvious reasons why the strip mall is different. First, it's typically a structure with masonry walls that hold up but are also supported by a lightweight steel bar joist roof. This roof support, when not exposed directly to the occupied space below, is concealed above one, sometimes many, suspended ceilings. This void space between the occupied space and the roof assembly allows fire, heat and smoke to grow sometimes for hours before anything is detected. 

Heat exposure
Having an undetected fire, even if it is smoldering, means the lightweight metal roof assembly is exposed to high heat for extended periods of time before the fire department arrives. With the relatively low heat of deformity for this type and arrangement of steel, it is not long before the joists can expand and push the walls, causing the roof to come crashing down.

The collapse happens because as the steel is heated it tends to expand. Given a steel beam of 100' length it is possible for that beam to expand as much as 1 foot when exposed to 1,000 F heat (1.). When the steel begins to expand, it is also softened and how that softened piece of steel behaves depends on what kinds of loads it is carrying. The deformity can occur in multiple directions simultaneously.

Faced with a fire in the upper voids of a strip mall, it is possible to delay or prevent the collapse by cooling the steel roof assembly. This cooling is accomplished by placing large volumes of water into the void space and onto the steel. Cooling the steel cannot undo the deformity that has already occurred but it can "freeze" the steel into place, slowing or stopping the collapse.

In many parts of the country, however, there are still older strip stores of various construction types. Because these structures tend to be wood frame buildings using dimensional lumber, the risk of catastrophic collapse decreases because the wooden roof assembly tends to burn away as opposed to collapsing. But because these structures are older it is likely that they have seen multiple renovations. This means that crews in these instances will have to penetrate multiple layers of suspended ceilings to access the void space, and there is still a significant void space for fire to travel through.

I remember being dispatched for a building fire at a strip center of older construction, when I was the officer on the engine. On arrival, we noticed a small fire in one corner of the building where the electrical service entered. After securing the electricity, we knocked down the visible fire. I noticed multiple suspended ceilings, and as we pulled them down we extinguished more and more fire.

After a few minutes, I thought we had it all. I walked outside and told command that we had the fire knocked, whereupon he told me to look back over my shoulder. There was fire shooting 40 feet into the air. I hung my head in shame and went back to work. After the fire, we noticed that we had to remove a total of seven different layers of ceiling to gain access to where the fire was burning. This was certainly a lesson learned. 

Combustible materials
The second major thing that sets strip mall fires apart from fires in residential structures is that you are dealing with a less compartmentalized space. Most strip malls house commercial occupancies, which have large open show rooms. The nearly constant presence of large amounts of combustible materials, most of them synthetic, complicatess the issue. All this adds up to a situation where standard lines with standard flows will simply not be enough.

Even modern fire protection systems may not be enough to prevent catastrophe. A significant fire can either overwhelm the sprinkler system, making it flow more than it was designed to, or it can grow unchecked above the sprinkler system. I went to a fire just the other day at a historic house. The fire began on the outside and extended into the building. Every single sprinkler head in the property was activated but the structure was still a total loss. In this case, the fire both overwhelmed and sidestepped the sprinkler system.

The layouts of strip mall interior spaces tend to be large and complicated. Crews operating in these spaces, especially crews not holding onto tag lines or hose lines, can find themselves quickly disoriented. Effective searches, when necessary and prudent, may require the use of tag lines or wide area search procedures. Remember though that wide area search procedures are part of a high-risk low frequency skill set. It is not a good idea to deploy search lines for the first time on a working fire in a strip mall.

A final major difference between fire in residential structures and fires in strip malls is strategic approach. The incident objectives are life safety, incident stabilization and property conservation. Strategy is what supports the incident objectives. At a house fire, we use a more aggressive search for possibly trapped occupants to support the life safety objective. The amount of aggression is moderated by the risk-benefit analysis.


AP Photo/Tim Larsen
Firefighters battle a four alarm blaze at a strip mall in Hamilton, N.J., in December 2004.

At a strip mall fire, the fire department should also place life safety as its primary objective. However, life safety includes the lives of both civilians and firefighters. The risk benefit analysis must be adjusted to account for the likelihood of finding trapped occupants, the likelihood of catastrophic building failure and the likelihood of rapid and overwhelming fire spread.

Having a significant rescue problem in a strip mall after hours is unlikely, but obviously a fire during the day means that there may be some people still inside the store. Those who remain inside may be frozen by fright or have what I call evacuation inertia, meaning their primary egress was blocked and they cannot move past that. Either way, the fire department will have to help get them out.

Risky searches
It is always possible for civilians to be trapped in a given structure, no matter what time, day or night. However, the mere possibility of a rescue is not carte blanche for the fire department to conduct unsafe searches. Conducting risky searches based solely on the presumption that someone might be trapped is a bad idea.

Fires produce CO well past the IDLH threshold and human skin burns at about 140 F. In other words, our ability to save a person trapped inside a burning strip mall is limited unless we can see them or know where they are in the building. Simply put, sometimes the search must be delayed until the fire is controlled. For me, the trigger to begin searching is the use of an interior attack. If your risk benefit analysis suggests that an interior attack is possible, then a search is also possible and must be conducted along with the fire attack.

Fires in strip malls are not impossible to manage, just difficult. Fire departments with strip malls in their response districts should pre-determine needed fire flows,  ensure that buildings meet and are kept up to code, enforce fire lanes or other access, and develop a standard operating procedure specific to these types of structures.

The first arriving company officer sets the tone and conducts what is perhaps the most pivotal risk analysis of the entire incident: whether or not to commit crews to an interior attack. Before crews are committed to an interior attack, the officer should:

• Determine that the fire is small enough to be quickly controlled by a single hand line — quickly means less than 90 seconds of flowing on the fire.

• Open the overhead space just inside the door with a long pole and confirm that the fire is not in the overhead. Sometimes a pole is not enough and the officer will have to direct crews to use a hose stream to move ceiling tiles out of the way. Obviously how much damage is done to the store is dictated by conditions found on arrival.

• Continuously monitor the overhead to prevent engulfment. You can do this with a thermal imager, but of course there is always the chance that the image will be blocked by ceiling tiles hiding fire. Perhaps the best way is to post someone in a position to keep a visual on the overhead. 

• Create or ensure the presence of a secondary means of egress for crews. A strip mall usually has large plate glass windows in the front of either side of a tempered glass door. This door has panic hardware of some sort and is outward opening. Before committing to an attack, ensure that the door is propped open or the glass and the horizontal cross members of the panic hardware have been removed. If and when an evacuation occurs, there will be no time for squeezing through small openings.

• In addition, a second line should be in place, capable of sufficient flow to support an escape should that prove necessary, and that the triggers for evacuating the structure are pre-determined.

Incident commanders should be prepared to promptly withdraw the crews if progress is not being made quickly. Personally I feel that if the fire is still burning when I arrive, all the people are out and I am more than a minute or two behind the first engine, then they are coming out. I do not, however, want to take away the latitude of the initial unit officer to determine if the fire meets the criteria that I’ve outlined above.

Interior attacks
There is little to gain from an interior attack and unfortunately much to lose. From a property conservation perspective, efforts should focus first on protecting the "long side" of the structure. In other words, protect the side of the building with the most occupancies between the fire and the end of the row. Once the fire is contained, efforts should focus on sending tremendous amounts of water into the overhead spaces. This does two things: it cools the steel, effectively freezing it into place, and it provides large water droplets to absorb heat. 

Always remember that it is easier for the owner to tear the entire building down and start over than to rebuild a burnt out section — and they can usually have that done before the death benefits are paid out to the firefighter families who lost their loved ones.

Perhaps the greatest difficulty I have personally had with fire in strip malls is convincing crews that the rules are different, and that the risk benefit analysis has been altered. This is in essence an asymmetric event, in that it is outside the ordinary day-to-day fire scenario. When faced with asymmetric events, the fire service is slow to embrace the power of a "certain slowness" that allows firefighters to fully engage their brains and truly weigh the risks and benefits of their actions.

In the aftermath of the tragic events in Charleston in June when nine firefighters died in a furniture store fire, I sent a message to those under my command, which included the following "lessons," which can apply to such scenarios.

• You cannot command a fire well from the inside.

• If you assume command or it is passed to you, sit in the cab and command the fire, write down the units. We know you are not a chief, not a certified incident commander, but you are not stupid. Worst case scenario: if you are worried or confused, make it an exterior attack until a chief officer assumes command. There will be a chance one day to prove yourself — strip mall fires are not it.

• Assume that the roof structure is a steel truss and that it will come crashing down sometime around 10 minutes after the fire started — not after you got there.

• An odor of smoke in a strip mall means that the fire is burning out of control above the ceiling tiles until you prove it is not. Open the ceilings as you enter. I do not care how much damage you cause. 

• If there are people inside the building when you arrive, get them out before you open any door, window, ceiling or anything else. Remember, it is on fire before proven otherwise.

• Never enter the main fire buidling from the rear.

• Dumpsters, trash fires and auto fires next to the building and the like can lead to dead firefighters; assume that the fire has entered the overhead space of the store and follow the suggestions above.

• If you see fire in a strip mall and decide to make an interior attack and that fire is not out in about 90 seconds, it is probably time to leave. If you and another line are flowing for 90 seconds and the fire is not getting smaller, it may already be too late.


Reference:
1. Jaehne, R. (2007). Street Smart Modern Construction Considerations for Firefighters. University of Illinois.

Charles Bailey is a career fire captain in Montgomery County, Md., with 16 years on the job. Capt. Bailey is currently assigned to Station 15, an area rich in bedroom communities, garden apartments and strip malls. In his spare time, he is an active member of the Branchville Volunteer Fire Company in Prince Georges County, Md., where he has served as deputy chief for nearly eight years. He has a masters degree in public administration and runs TinHelmet.com, a fire-related website. Most importantly, he says he realizes that none of this matters unless the line firefighters, officers and incident commanders are presented with good information and good methodologies that will allow them to make informed decisions about risks.

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