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Vertical Ventilation Video - What do your eyes tell you?

The following video clip was sent to me by a reader who was responding to my last post regarding vertical ventilation:
In it, you will see two firefighters vigorously cutting a roof as fire burns below. The provider of this link pointed out the immediate improvement in interior conditions as evidenced by the lift in the smoke layer that occurred as the fire vented. Taking a contrary position, I would point out that the smoke was turning white prior to the creation of the overhead exhaust path, likely due to the application of water by the interior hose team.

Still, instead of engaging in a debate about the actual cause(s) of the changes seen, or whether this example refutes or supports my position that nothing good comes from cutting rooftops, I would suggest that one of the real values of this clip is to demonstrate the importance of performing fire suppression research in a controlled, “laboratory” setting. Despite the limitations of such artificial environments, there is no other way to control variables, time interventions, and monitor conditions, thereby allowing for the accurate determination of the causes and effects of our fireground actions. Otherwise, we’re left arguing about what we’re actually seeing, and likely forever unable to come to a definitive conclusion.

Apart from the debatable effects of the competing actions of applying water and increasing air flow, there are two other observations regarding this video I would like to share: First, the two firefighters demonstrate exceptional skill and ability in cutting the roof. They were in full PPE and on air; had all the tools needed (chainsaw, axe, and pike pole); chose the proper location (near the peak); and exited the roof immediately after completing their task. As much as I believe roof ventilation to be anachronistic, it’s great to watch someone do their job so well (and, if the Smithsonian ever creates a museum of firefighting methods, I would recommend this for the video archives).

The other thing illustrated here is how immensely difficult it is to coordinate ventilation above with water application below. While the roof was opened just after the start of water application, the sequence recommended by even those who are “pro” tactical ventilation, there was no apparent attempt at “timing” these two interventions, nor, given the smokey, noisy, and rather frenetic setting, likely any ability to do so. Also, even these obviously talented firefighters would have been delayed significantly, and missed their Goldilocks moment (i.e., not too soon, not too late, but at just the right time) if they had been unable to stand on the roof and instead needed to work off of a ladder. Watching this expert performance shoots a big h*** in the frequent argument that roof ventilation failures are usually the result of poor technique. I would, again, argue that it’s a complex, dangerous, wast of time. It doesn't help, even when, as in this case, it’s performed flawlessly.

Finally, thanks for all the comments on my last post, be they cheers or jeers. Rather than wasting effort defending my credentials, motives, and reputation (though I’m proud of all of them), and with apologies to any readers who found my writing insulting, inflammatory, or downright cocky (made ya look!), I would direct our attention back to the central issue: careful experiments have demonstrated that increasing ventilation to a structure fire increases the intensity of its burning (not really news, but a good reminder) more than it releases the products of that reaction (actually, revolutionary). Viewing our tactics with those facts in mind, we can either make adjustments, or not. The renewed awareness of how ventilating a fire can worsen interior conditions has lead many in the fire service to emphasize the importance of its delay until after fire control. (There is, of course, much discussion about the actual timing - Ready to start water flow? Already started water flow? Fire is out? - but it is generally agreed that enhancing air flow to a free-burning fire is a bad idea.) Some of us have also taken the next step and decided that eliminating the very purposes for which we were performing a difficult and dangerous action (in this case, cutting roofs) is sufficient reason to abandon that action, allowing us to instead perform others that are actually proven to be helpful.

Many of us disagree - some even passionately - about the interpretation of the results of fire dynamics studies, as well as the relative benefits of different tactics and methods, and even the addition of a letter to our favorite acronyms. The video clip that inspired this post came to me as a result of a discussion with a vertical ventilation advocate in response to my prior post denouncing that practice. It has now been woven into another discussion in which you are all invited to participate. This is but a small example of the ever-expanding, and likely never-ending, evolution of our craft, a process that I am honored to be a part of.


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Comment by Mark J. Cotter on March 22, 2018 at 12:01pm


Thanks for joining the discussion.  I can't argue with experience, or with the success that many other firefighters report having with vertical ventilation, and would just point out their limitations.  Recall that we were all once sure, based on reports by firefighters, that exterior streams spread heat and steam further into a structure, and were therefore harmful to anyone still inside.  Careful experiments confirmed some of these observations with fog or rotating straight/solid patterns, but demonstrated no such effect if the proper stream was used (straight/steep/still), increasing our options for, and decreasing the time to initiate, water flow onto the fire.  

Going back to the video that inspired this post, can we be sure of what caused the improvement in conditions?  Water flow, roof opening, ceiling opening, horizontal ventilation?  In your instances, with the heat and smoke clearing as the roof opened, was roof ventilation the best method, or would horizontal or PPV have worked as well or better?  These are the questions that we must rely on a scientist with a pocket protector to answer.  

Research has shown us that the window for the benefits of vertical ventilation is particularly narrow - the increase in the output of smoke and heat is almost immediate, especially if the h*** is directly above the fire - confirming your comment about the importance of the proper application of water.  Objectively comparing the various methods for clearing the way for hose crews operating on the top floor of a burning building would be a great study.  In the meantime, we certainly all have our favorites, and those that seek mastery of their procedures are sure to enjoy more frequent success.

Comment by Nicholas Papa on March 21, 2018 at 8:12pm

Amen. “And that’s all I have to say about that.”

Comment by Paul Richardson on March 21, 2018 at 8:04pm
*isnt helpful
Comment by Paul Richardson on March 21, 2018 at 8:01pm
I’m not a scientist or as Forest Gump said “a smart man” I don’t hold all the certifications you fellows have. Nor do my 13 years stack up against your seniority. I’m just a poor knuckle dragging engine captain in the 4th largest fire department in the country. My question is how did my imagination play the same trick on me as countless other firemen. I’ recall crawling around in a nasty environment getting my tail tail kicked in and pushed to floor only to hear the saws above me and almost instantaneously feel relief. I’ve been stumbling around in zero visibility only to have h*** opened up and be able to find fire. If vertical ventilation is helpful to engine companies then what was taking place?
The one thing missing from all the anti vertical ventilation studies is proper application of water. A good aggressive engine crew with a good aggressive truck will work wonders. Timing is accomplished with training. That’s why it’s important that crews stretch correctly and make the push. I’ll take a quality crew over a pocket protector and a scientist any day.
Comment by Mark J. Cotter on March 21, 2018 at 4:55pm


My continued reference of the UL Vertical Ventilation study is due to it being so applicable to the question at hand, and its findings were consistent and repeatable.  In the way of confirmation, there were similar findings in the UL Attic and Exterior Fire studies , showing that ventilation before fire control was detrimental, rendering the fire harder to control, rather than easier.  Now, they did not test every construction type or geometry, and different settings could react differently, but neither has anyone performed objective testing that supported our prior beliefs in the benefits of ventilation, which were based on theories and anecdotes.  We know that opening a roof improves conditions, if the fire is already controlled.  If not, the fire better be controlled soon, or things will worsen.  Back to my basic premise, if we agree that ventilation should not be performed until the fire is controlled, why go to the trouble of using the most difficult and dangerous method available, even if we're good at it? 

Comment by Nicholas Papa on March 21, 2018 at 3:26pm


First off, I am far from an expert in anything, but I appreciate the sentiment.  Once again, you are judging the tactic as a whole based on the results experienced in one particular sequence.  You keep referencing vertical ventilation solely in the context of pre-water application.  But if it is not initiated with fire attack, is it truly coordinated - well that is debatable.  With that being said, how could you possibly say the tactic flunked when you only have a single sample of data to work from? Where is the rest of the data to show the supposed detriments of vertical ventilation when coupled with fire attack?  This is the piece that you have yet to address in any of your comments.  You only cite your personal opinion that coordination is difficult - which you even admit is a weak argument.  There are departments that perform this operation on a daily basis (some multiple times) with continued success.  The key, as with anything else, is competency.  

Comment by Mark J. Cotter on March 21, 2018 at 1:45pm


Unfortunately, it seems that semantics are at the heart of this issue.  Our understanding of ventilation, horizontal or vertical, always included an awareness that it can increase the rate of combustion in a compartment, so ventilation has always been required to be "coordinated".  But, we once believed that doing so as we were advancing on the fire with hoselines provided clearing ahead of the interior teams.  It was that attack benefit, as well as a lack of awareness of just how quickly fire reacts to increased air flow, that lead us to believe that opening just a little early might not be such a big deal, and justified the risk and difficulty involved with performing roof ventilation.  And, it was that justification that was removed by the findings of the research.  To use my word, that's how it "flunked".

This left us with the choice of what method best removes products of combustion once the fire will no longer respond to ventilation by producing more.  In other words, what is the best method of performing "coordinated ventilation"?  Your position is that cutting the roof and creating an opening after the fire is in a controlled state is best, and I agree with your rationale for the "chimney" effect that will result.  I have already outlined my concerns regarding the difficulty synchronizing that action with interior water application, and the perils of failing to do so.  (I am also keenly aware that I am debating with an expert at roof ventilation, over a video clip showing other experts at roof ventilation, so these arguments might seem weak.)  Regardless, my take is that opening a window and using a fan or hose stream is a better method for performing ventilation, eliminating the passive benefits of vertical airflow by utilizing active measures, which are also, all things considered, easier, faster, and safer.

Comment by Nicholas Papa on March 21, 2018 at 9:55am

Let’s forget the semantics and get back to the issue at hand here. Where is your data that shows that coordinated vertical ventilation “flunked”...I must have missed that section of the study. Again, you are misusing the data of vertical ventilation without water application in attempts to discredit the effectiveness of the tactic when appropriately executed. When water is being applied and actively cooling the fire, controlling its output, the ventilation opening will not be overwhelmed as you say. Again, where is your evidence of a coordinated vertical ventilation operation negatively impacting operations? The objective measurements you speak of, do not exist...yet. As the study showed, which you acknowledged, vertical ventilation is the most efficient means of air exchange - producing a uni-directional flow. By creating the opening directly over the fire, the greatest pressure differential, the thermal buoyancy aids in the exhaust process and promotes lift of the thermal balance and channeling of the fire up and out - providing relief for the crew below and facilitating their extinguishment and search efforts.

Comment by Mark J. Cotter on March 21, 2018 at 6:09am


Myopic: "lacking imagination, foresight, or intellectual insight."  I get that word thrown at me a lot, but I have to say I put a lot of all of those things into forming my opinion. right or wrong.  Anyway, we agree on the research findings, and are left with discussing their implementation.  Your position is that the increased potential for worsening interior conditions by early ventilation can be overcome by working harder at roof ventilation performance, and mine is that we would be better off just pointing the nozzle out the window, or becoming more diligent/proficient with the use of fans.  The passive release of smoke from a cut roof, even when well-coordinated, cannot match that which can be propelled out a window or door.  Roof ventilation is certainly "time-tested", but when subjected to objective measurement, it resulted in an increase in combustion and produced more heat and smoke than could be released by the h***, so it flunked that test.

Comment by Nicholas Papa on March 20, 2018 at 10:14pm


I am well-versed in the research and am on the panel for the latest study on coordinated fire attack.  The problem is that your personal interpretation of the data does not accurately reflect the tactical recommendations established by those previous panels.  You are fixating on one singular aspect of the study and it’s data, ventilation WITHOUT water application, to validate your (myopic) opinion of roof ventilation.  The effects of UNcoordinated ventilation, horizontal or vertical, has been understood and documented since the 1800s (i.e. James Braidwood) - this was not a scientific revelation.  What the study did was provide us with empirical data to better understand the movement of air and it’s impact on fire behavior and the environment.  The data showcased the ventilation-controlled nature of today’s fires and its increased responsiveness to our operations.  This merely makes a case for increased positional discipline and more precise coordination of ventilation with fire attack and and isolation (door control).  We shouldn’t arbitrarily relegate a time-tested tactic to the trash pile simply because the margin for error has gotten just means we need to be smarter and more diligent/proficient.  I urge you to start looking at roof ventilation as it was intended, as a coordinated/supportive effort.  When appropriately placed and timed, the benefits of topside ventilation are irrefutable.


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