What are your thoughts on ventilation, both at work and at my vol. station we use positive pressure. we either take out the windows or open the gable ends or vents but in the last 10 years I haven't seen a roof cut, but maybee 3 times out of a couple hundred fires. And no negative pressure fans at all.
We use a variety of ventilation. If we need to open a roof, we open the roof. depending on the construction of the building and or layout, we select the best fan for the job. In a fire situation, I love Hydrolic ventilation. It seems to be a lost art to some folks, but my preferred method to draw the smoke away long enough for a peek at whats going on while removing some heat as well
My department still cuts holes in roofs and we find it very effective. I personally have cut holes at numerous fires in the past year. The last time I checked, the smoke and heat still rise so cutting vent holes in the roof is still a very good way to go. We train 2 or 3 time a year on this when we acquire house for live burns.
The ventilation you select really depends on fire progression, location and extent, and construction/layout. We like to use PPV but make roof cuts as needed to make things happen. Hydraulic ventilation works great especially in non-combustible/reinforced concrete construction (we have a lot of condos like that- it's like fighting fire in a gun barrel) make the push from the hall and break out the sliding glass door, then push it out to the parking lot.
My approach, vent early vent often! PPV does well as smoke removal but posses too many problems in fire control in balloon frame which we see alot. Horizontal 1st then move up unless backdraft signs are present. Another concern is commercial strips, this posses the problem of venting behind and already advancing hose team. Be very, very careful, rapid fire spread is a concern when taking plate glass windows.
Am I hearing this right when you say you dont believe in cutting vent holes, as said before smoke and heat rise theyre for, proper vertical ventilation is essential on most all quality fires. Are you gonna cut a hole on your small first floor of the 2 1\2 wood frame probably not but to say you never use vertical ventilation is nuts. What do you guys do for fires in buildings with balloon frame construction or a 2nd floor job? Do you let your engine crews take a beating on the fire floor I mean proper ventilation makes or breaks a fire. And to the brother above who states he would hydraulically ventilate a room i hope you would do it after the fire was out as to not steam your crew. I mean all depts are different but i just think to say vertical ventillation is out of the question is nuts.
Since I am an advocate of ventilation, let me add my two cents worth. It all starts with an effective exterior building size-up. Information gathered will asssit in determing the type of ventilation needed and where to ventilate. My message is this: Ventilation must be accomplished BEFORE firefighters enter the building whether its vertical or horizontal. If you want to supplement it with Postive Pressure Ventilation Tactics, that is fine, but ventilate by breaking windows, cutting a hole or open a door before entry is made. We must realize that the enemy (fire) has changed. The BTU output today is three times what it was many years ago and this requires building ventilation up-front. You might say, "we don't have the personnel" to do this, I say nonsense. My department developed a procedure whereby a three person engine company could in most cases address the issue of up-front ventilation before they made entry. As far as hydraulic ventilation is concerned, I agree it is a great way to ventilate, however, based on my experience I offer two observations. First, this method must performed after the fact, you must crawl through the crap, knock down the fire then ventilate. I refer to this as ventilating in the 9th inning rather than the first. Second point, be careful when and where you use it, it can cause excessive water damage. Early in my career, I ordered hydraulic ventulation in a second floor apartment fire, result was we did excessive damage to the area we were in and the apartment below. I learned a good lesson. Bottom line..Firefighter Safety, ventilate early!
Sometimes tools and ideas get in the way of common sense. Simple facts people forget Heat raises and getting smoke out of a building is important but the first part of venting is removing heat! We use all the ways others have brought up but please make sure someone is in charge of venting and its not an after thought I was in a building recently trying to find a fire that I could feel I could hear I could smell but I couldnt find..( was in a 14 inch space between a wire lath ceiling and the floor above) someone decided to put 2 large PPE fans in the first floor doors to clear some smoke. Well this help me find the fire as it blew out both sides of the building and dropped on 5 of us. Lesson learned when I got out and watch a building burn that shouldnt have and the person that was in charge of the fans understood my displeasure. I know venting is a tool but like any if its not done right it can get you hurt.
Dan you are absolutley correct that someone needs to be in charge of any ventilation operation. On the subject of Positive Pressure Ventilation (PPV), if it is going to be used, the bottom line rule is that you never ever start it up with crews in the building. I have been teaching the use of PPV since 1987 and based on my research and experience, when incidents happen like the one you described, the fans were used in-correctly and proper procedures were not followed. In my opinion, these kinds of mistakes are caused by a lack of training and not understanding the concept.
We do what most of the replies have said: do what it takes. I just cut three holes at a fire a couple weeks ago. We have crap for manpower, and for the "room and contents" fires usually we do PPV or hydraulic. If we have a real fire and it needs ventilation, by all means we cut the roof. With manpower issues, you need a good IC with a plan; if you need to cut first, no matter how difficult, do it.
We use whatever method seems appropriate for the call. If the fire's hot and we can cut a hole in the roof, we do, if it's a single story one room structure (large garage), we pop out the windows until we know what we're dealing with. PPV is usually only used to clear the smoke out. It does have it's advantages, and it sure can help you find the hot spots... lol! I've seen it used too early in a balloon construction home... not good.
Since balloon construction has been mentioned in several comments, I'd like to address that issue and the use of Positive Pressure Ventilation (PPV) techniques. Lets consider a building with balloon construction with fire in the basement. If you know your first due area and recognize this type of construction then you know that the fire will probably extend into the attic. Why? In Firefighter One and Two Training, we are taught that the products of combustion follows a path of least resistance. Another way to say this is that the products of combustion will travel from an area of high pressure to an area of low pressure. Heat increases pressure (Fire Positive Pressure). The area of highest pressure is in the fire area. In the basement fire scenario cited above, the products of combustion will travel from the fire area in the basement to an area of lower pressure, one of those areas being the channels formed by the balloon construction and into the attic. This is a normal process. How do we solve this problem? We position attack lines in key points, one of them being above the fire or in the attic to check for fire extension. We should do this before the fire shows itself in the attic. This process is simply good Tactics and Strategy. Without effective ventilation, we perform these actions in either zero visibility or in less than desirable visibility. How effective can you be in poor or zero visibility? The main point is that even before you arrive on the scene, the fire is already going up the walls and into the attic. If you don't position a line to stop the fire extension into the attic, the roof will probably be destroyed. Now, lets introduce PPV into the scenario. It is imparative that the basement be ventilated. Break windows first in the area of the fire allowing the products of combustion to follow to an even closer path of lower pressure. Start PPV before anyone enters the building. Be sure the door to the basement is open. What you gain is visibility, a slow down of the extension into the attic because most of the heat etc is now exiting out of the basement and to the outside. Advance a line into the basement, get a line to the first floor and another line to the attic. Regardless whether PPV is used or not, if proper Tactics and Strategies are not employed, the building will probably be destroyed.