A few days ago I posted a video and subsequent post on Truss Roof Burn Testing. The video was intended to give you the reader a healthier respect for how fast a roof system itself may collapse when challenged by fire.
Brian Brush from www.fireservicewarrior.com made the comment on that post that this may not tell the entire story, and could be used as a scare tactic to encourage people not to perform vertical ventilation. I responded to him that I thought my intent was self-explanatory, but I do not want anyone to think I am not telling a full truth, or encouraging a less aggressive fire service. What I am advocating is a more informed, intelligent, and safer operating fire service by providing preparation on the front end (training, physical fitness, wearing all of your gear). Simply put the old adage of “balls, water, and firemen put out fire” in my opinion is caveman like and is no longer acceptable in today’s fire service.
Thats is why I posted the below video. It is a joint test from NIST, and the City of Phoenix Fire Department. In the portion seen in the video they take 4 identical structures (dimension, and contents wise) and perform burn tests on them to show how long the structure would last without fire department intervention (water on the fire) They do also add firefighters weight in gear to the roof structure to get an idea of how that impacts collapse time. The only thing that changed in the study was the material used in the structural elements, and the roof covering.
You can see for yourself no matter the building material, or the roof covering the collapse times were almost identical. Remember these fires were not started in the roof structure they were started in the “living space” of a sheet rocked room.
So again what we have to do is take these results and put them into terms that impact us on the street. Do we look at these numbers as gospel, probably not, several influences could impact these numbers in either shortening, or lengthening collapse time. What we can do is take them as a baseline for the average home, and use them as a training tool.
In the average home we found in the study that no matter the construction, the contents of the room generated a large enough fire to cause building collapse around the 17 min mark from time of ignition. You take that number and look at your department and ask some of these questions.
What are our response times?
What is our staffing level?
What is our apparatus responding on a fire, and how long will it take for a full complement to arrive on scene?
Do we have the people arriving to impact a fire in this time frame?
Like I have said before the answers are different for everyone. For my full-time department with lower response time (5-7mins) I can say with relative certainty that if the situation presented itself with our staffing, and response we can do a marginal job of going to vent a roof. In my part-time department with 2 man staffing, no ladder truck, and response times ranging from 5-20mins it would be almost impossible to be succesful at venting a roof. FDNY, DC, Baltimore, Chicago, and other large urban departments will have a higher success rate, but just because they can do it does it mean we should it not in the same situation.
I do not question the skill level of a FDNY fireman, and I have learned a lot from several of those guys in classes all over the country. However what they do does not always apply to me and my department as our districts, staffing, and tools are different. While I have only vented 2 flat roofs in my career, I would venture to say very few big city fireman have vented the roof on a log cabin (which I did in the rural section of the county I vollied in).
Like I have said in previous posts, you have to perform a self assessment of you and yours and determine your capabilities, and how you do business. Maybe roof venting is not for your department, and that is ok. You then have to decide how you are going to ventilate a structure in order to control fire spread, and allow for relief to the interior crews.
I plan on having a post up within the week on some alternative methods to perform roof venting, i just have to search through the thousands of pictures I have and locate some training photos we took a few years ago.
Please feel free to leave any comments, or feedback in the comments section, email, or on twitter (@averagejakeff)
As usual thanks for reading, spread the word, and STAY SAFE![vodpod id=Video.15306717&w=425&h=350&fv=%26rel%3D0%26border%3D0%26]