Vertical Ventilation

Replies to This Discussion

Permalink Reply by Matt Thomson on July 14, 2009 at 12:51pm

Chris, yeah it works. A lot of departments got away from vertical ventilation for various reasons but most departments that still do it know the benefits. There is a good video on you tube that illustrates the effectiveness of vertical ventilation. It's taken from Houston, TX and shows a one story wood frame. The brothers in Houston do a good job of opening the h*** and as soon as that happens you see the smoke lift around the building. Granted... this was vertical venting supplemented with PPV but it's still a good illustration.

Permalink Reply by Michael Bricault (ret) on July 24, 2009 at 4:52pm

-The technique does in fact work. That being said, there are some very specific parameters that must be meet in order for vertical venting to work properly.
-First and foremost is that the truck company must be on the roof and completing the vent whole before the engine makes it into the fire area. Otherwise the venting tactic is nothing more than unnecessary damage to the structure.
-The reason many FDs, especially smaller ones are getting away from this tactic, aside from not understanding the proper application of the technique, is a lack of manpower and/or a lack of ladder apparatus. When the ladder arrives it is usually later in the incident, usually after the engine is in operation. When the ladder does arrive it may not have enough personnel aboard to perform all of the necessary tactics immediately required.
-The fire must be a top floor fire or in an area such as in direct proximity to the stairs that natural convection from the vertical venting will provide a beneficial result.
-There must be a specific need for the tactic based on the structure itself. Typically speaking, the tactic of vertical venting was intended to address structural fires in balloon frame construction type occupancies. The use of vertical venting in a typical private residential platform type construction is almost a waste of time. And many of the suburbs that sprang up in the 80's have created communities in which the tactic of vertical ventilation is not only unnecessary it is unsafe. Remember the platform construction that was used employing studs 18-24 inches on center held together with wood joist staples and the OSB decking?
-Consider the points Tom Brennen made about vertical venting in a private residence of platform type construction with a room and contents fire. Once the proper location is identified for the cut, then the cut is made, firefighters must use hooks to push down the ceiling inside. But what about all the storage in the attic space. Christmas, wedding stuff, baby clothes.... yada yada yada.
-Furthermore, once members have completed breaching into the fire compartment, they will have succeeded in pulling the fire (because venting is intended to work before the fire is under control) into the attic area thus turning a room and contents fire into a structure fire.
-Because of the points made here, some FDs will not commit personnel to vent a peaked roof. Others will not commit firefighters to the roof if a truss is even suspected.
-The bottom line is that vertical ventilation is becoming a dying art for many reasons. Whether it is due to a lack of manpower, a lack of ladder companies or their late arrival; or whether it is because of a lack of understanding of the tactic itself or the very structures precluding the need for or ability to perform the tactic.
-Vertical ventilation does work but under very specific applications.

Permalink Reply by Esteban Andrés Cabrera Rebolledo on September 21, 2009 at 9:13am

Look that:
http://www.youtube.com/watch?v=_BeEG9LEzjU

Boston Fire I think..

Vertical ventilation does work, if this really needed. If don't, you waste time and threat the firefighter with roof collapse.

For other hand, look the windows on any structural fire, and you can see the upper third of the window full with smoke, so if you cut a h*** right up that smoke, anything go out from the windows, making better conditions to firefighting interior opration, any people trapped inside.

Permalink Reply by Michael Bricault (ret) on September 21, 2009 at 11:04am

-Esteban, this is indeed an interesting video though I'm not sure where the video was shot. It is most certainly not the city of Boston, Massachusetts.
-Given the fire conditions showing and the condition of the structure I believe that roof operations are not necessary and are needlessly endangering to firefighters in this particular operation.
-If roof operations are to take place than there must be multiple ladders raised so members have secondary methods of escape should conditions change.
-One point many firefighters and commanders overlook is just how quickly safe roof operations must be conducted in order to get members off the roof that much sooner.


Esteban Andrés Cabrera Rebolledo said:

Look that:
http://www.youtube.com/watch?v=_BeEG9LEzjU

Boston Fire I think..

Vertical ventilation does work, if this really needed. If don't, you waste time and threat the firefighter with roof collapse.

For other hand, look the windows on any structural fire, and you can see the upper third of the window full with smoke, so if you cut a h*** right up that smoke, anything go out from the windows, making better conditions to firefighting interior opration, any people trapped inside.

Permalink Reply by Esteban Andrés Cabrera Rebolledo on September 21, 2009 at 12:32pm

maybe a ladder truck like secondary route scape...

I agree with your points.


Michael Bricault said:

-Esteban, this is indeed an interesting video though I'm not sure where the video was shot. It is most certainly not the city of Boston, Massachusetts.
-Given the fire conditions showing and the condition of the structure I believe that roof operations are not necessary and are needlessly endangering to firefighters in this particular operation.
-If roof operations are to take place than there must be multiple ladders raised so members have secondary methods of escape should conditions change.
-One point many firefighters and commanders overlook is just how quickly safe roof operations must be conducted in order to get members off the roof that much sooner.


Esteban Andrés Cabrera Rebolledo said:

Look that:
http://www.youtube.com/watch?v=_BeEG9LEzjU

Boston Fire I think..

Vertical ventilation does work, if this really needed. If don't, you waste time and threat the firefighter with roof collapse.

For other hand, look the windows on any structural fire, and you can see the upper third of the window full with smoke, so if you cut a h*** right up that smoke, anything go out from the windows, making better conditions to firefighting interior opration, any people trapped inside.

Permalink Reply by Eric Myers on November 2, 2009 at 11:35am

Chris-
I have noticed the 4 x 4 h*** go by the wayside. The amount of BTU's being generated with synthetics just doesn't allow for the traditional size cut. You have to assess the amount of fire and smoke being produced from the h***. Is it coming out under pressure of volume? If pressure, reassess and start cutting a bigger h***. Google "Coffin cuts" and you will get a great method to increase the h*** size as needed. We must also consider the type of building materials being used and consider the risk v. reward. Also must ask our selves why are we going to cut this h***? Strategy? Hope this helps get the gears turning. Be safe.

Permalink Reply by Shareef Abdu Nur on November 3, 2009 at 2:09pm

yes, vertical ventilation does work. 4x4 holes can change conditions for the interior members quickly. not all situations call for vertical ventilation. many situations demand horizontal ventilation, but this is where good size up comes into play.

Permalink Reply by Brandon Krause on November 3, 2009 at 2:42pm

As far as does it work, yes it does! As Michael said you have to meet certian requirements though. When dealing with opening size, I teach to open up an area equivalant to approx. 10% of the roof size. This may require multiple openings which are acceptable for our department as long as roof conditions allow for this. Once roof conditions no longer allow us to stay up we are wasting our time opening it up anyway and need to focus on getting more water on the fire.

Permalink Reply by Jacob Smith on November 9, 2009 at 6:13pm

yes vertical ventilation does work. At my department we don't vent all that much or see that much fire for that matter. but we do train on it all the time. We have deen going away from the recuit school method of doing a 4 x 4 cut and started teaching a 4 x 8 aka "trench cut" there are some good video's on youtube of the trench cut method I also think there is one on the training min called 7, 9, 8 cut also.

hope this helps.

Permalink Reply by Michael Bricault (ret) on November 16, 2009 at 8:13pm

-Jacob, as a matter of technical correctness the 4x8 foot ventilation h*** is not a trench cut, its just a big vent h*** measuring 4x8 feet. This is not minutia; rather it is a technical point of fact and in order to better understand the mission the proper terminology should be used. Is the roof team directed to cut a vent h***, extend a vent opening, cut a trench? Will they make a three cut, knock out inspection h*** or use curf cuts to assess roof conditions?
-By definition, a trench cut is a ventilation h*** in a roof the extends from exterior wall to exterior wall. For example, a trench cut on a taxpayer roof would be 4 feet wide and 50 feet long. That means at the very least, 108 linear feet of cutting. More cutting if you factor in that a lateral cut will be need every eight feet in order to facilitate pulling from the roof team. Thats a total of 133 linear feet of cutting.
-To achieve this cut in a timely fashion so as to be definitive would require four saws operating simultaneously and will typically take more than ten minutes to accomplish.
-That being said, a trench cut is not a technique to be used on a taxpayer, despite the prevalence of the tactic in relation to fires in taxpayers. The reason being id that it takes far to long to achieve and exposes the eight man (at a minimum to achieve this amount of cutting and pulling) roof crew beyond a safe time limit. Remember, if the trench is being considered than the structure on the fire side is being written off. In a poorly constructed taxpayer, that is a dangerous amount of fire exposure to the roof supporting framework.
-In fact, the trench cut was designed to address fire in a very particular type of building; the H style building. In this type of structure, the building itself creates a natural narrowing of the structure, a choke point in which a trench cut will facilitate complete traversing of the roof surface. This narrowing of the roof surface, usually a hallway connecting the two larger portions of the building, is the proper location to cut a trench.
-Following this, in order to properly use the trench technique, the roof must provide a narrowing area in which to cut the trench. Everything on the fire side of the trench is understood to be written off; the trench is where firefighters make their stand. The narrowing part of the building allows for more aggressive firefighting as there is less structural involvement and a complete wall to wall roof vent h***.
-True trench cuts are very time consuming, labor intensive operations employed only when the structure provides a narrowing choke point in a fire scenario in which a large portion of the fire building is being written off.

Jacob Smith said:

yes vertical ventilation does work. At my department we don't vent all that much or see that much fire for that matter. but we do train on it all the time. We have deen going away from the recuit school method of doing a 4 x 4 cut and started teaching a 4 x 8 aka "trench cut" there are some good video's on youtube of the trench cut method I also think there is one on the training min called 7, 9, 8 cut also.

hope this helps.

Permalink Reply by Jacob Smith on November 25, 2009 at 11:43pm

that was my error, what i meant was that i've heard it be called a coffin cut not a trench cut.

Michael Bricault said:

-Jacob, as a matter of technical correctness the 4x8 foot ventilation h*** is not a trench cut, its just a big vent h*** measuring 4x8 feet. This is not minutia; rather it is a technical point of fact and in order to better understand the mission the proper terminology should be used. Is the roof team directed to cut a vent h***, extend a vent opening, cut a trench? Will they make a three cut, knock out inspection h*** or use curf cuts to assess roof conditions?
-By definition, a trench cut is a ventilation h*** in a roof the extends from exterior wall to exterior wall. For example, a trench cut on a taxpayer roof would be 4 feet wide and 50 feet long. That means at the very least, 108 linear feet of cutting. More cutting if you factor in that a lateral cut will be need every eight feet in order to facilitate pulling from the roof team. Thats a total of 133 linear feet of cutting.
-To achieve this cut in a timely fashion so as to be definitive would require four saws operating simultaneously and will typically take more than ten minutes to accomplish.
-That being said, a trench cut is not a technique to be used on a taxpayer, despite the prevalence of the tactic in relation to fires in taxpayers. The reason being id that it takes far to long to achieve and exposes the eight man (at a minimum to achieve this amount of cutting and pulling) roof crew beyond a safe time limit. Remember, if the trench is being considered than the structure on the fire side is being written off. In a poorly constructed taxpayer, that is a dangerous amount of fire exposure to the roof supporting framework.
-In fact, the trench cut was designed to address fire in a very particular type of building; the H style building. In this type of structure, the building itself creates a natural narrowing of the structure, a choke point in which a trench cut will facilitate complete traversing of the roof surface. This narrowing of the roof surface, usually a hallway connecting the two larger portions of the building, is the proper location to cut a trench.
-Following this, in order to properly use the trench technique, the roof must provide a narrowing area in which to cut the trench. Everything on the fire side of the trench is understood to be written off; the trench is where firefighters make their stand. The narrowing part of the building allows for more aggressive firefighting as there is less structural involvement and a complete wall to wall roof vent h***.
-True trench cuts are very time consuming, labor intensive operations employed only when the structure provides a narrowing choke point in a fire scenario in which a large portion of the fire building is being written off.

Jacob Smith said:

yes vertical ventilation does work. At my department we don't vent all that much or see that much fire for that matter. but we do train on it all the time. We have deen going away from the recuit school method of doing a 4 x 4 cut and started teaching a 4 x 8 aka "trench cut" there are some good video's on youtube of the trench cut method I also think there is one on the training min called 7, 9, 8 cut also.

hope this helps.

Permalink Reply by Will Anderson on January 12, 2010 at 10:23pm

I've attached a couple of pictures that, I think, show how it helps. In the pics, our attack crew was having a hard time making headway. Once the roof was opened up, they no longer had any problems moving in. Textbook! Hope this helps.

Attachments:

• Vertical ventilation.jpg, 1 MB
• Vertical Ventilation-2.jpg, 1023 KB

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