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Thread: Preventilation

  1. #1
    Firehouse.com Guest

    Question Preventilation

    This is coming from a guy on a department that doesn't cut too many holes in roofs. My question is this: Is there any efficacy to sending crews to the roof of a structure for "pre-ventilation" or "Prophylactic" (for lack of a better term) cutting of a hole that can be left in place, and then if needed, can be louvered or pulled open to get the fire and gases out; if not, needed, it's been cut, but doesn't need to be opened. It may sound like a crazy idea, but I just read about it a while back, and was wondering if it's a good or a bad thing.

  2. #2
    Forum Member
    Join Date
    Jan 1999


    It would seem to me that if you are going to send people up and cut the roof, then you might as well have it open. If you didn't need it, well ...ok....you didn't need it. The damage will be the same either way, and why mess around with it. Go up, cut your hole, conduct any further survey needed, and get off.

    Short answer, but I haven't finished my coffee yet.


  3. #3
    Forum Member Bones42's Avatar
    Join Date
    Mar 2001
    Pt. Beach, NJ


    I have to agree with hfd66truck, why cut the hole if your not going to open it? If you don't need vertical ventilation, why damage the roof. If you need it, cut it and open it.

  4. #4
    District Chief distchief60b's Avatar
    Join Date
    Mar 2001


    I agree with HFD66Truck and Bones... If ya go to the roof...then you better be opening up something. I have used louvering for ventilation...but not in the terms of cutting it to be done later.
    09-11 .. 343 "All Gave Some..Some Gave ALL" God Bless..R.I.P.
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    The comments, opinions, and positions expressed here are mine. They are expressed respectfully, in the spirit of safety and progress. They do not reflect the opinions or positions of my employer or my department.

  5. #5
    Junior Member
    Join Date
    Jul 2002


    I have to agree with what the others posted. If you dont need the hole, dont send someone up for the heck of it. There are hazards associated with vertical ventilation, dont risk your crews unless its neccessary.


  6. #6
    Senior Member shammrock54's Avatar
    Join Date
    Jul 2001


    I'm w/ the others and much like your Prophylactic comment, you dont pull out your tools and pregame the job and not "do it". if you decide to "get up"(on the roof ) you should cut.
    Member IACOJ & IACOJ EMS Bureau
    New England FOOL
    As always these are strictly my own opinions and views

  7. #7
    Join Date
    Apr 2001


    phyrngn could you have been reading about a trench cut?
    Other than that when a hole is needed you cut it , pull it
    and push down the ceilings depending on the type of construction.

    Stay Safe

  8. #8
    Forum Member DeputyChiefGonzo's Avatar
    Join Date
    Aug 2000
    Somewhere between genius and insanity!


    No way! What if you cut your "prophylactic vent" in the wrong location? Ooops!

    In order to do this, you would have to cut multiple holes in a roof to cover the area.

    What type of roof are we talking about?

    Lightweight truss roof construction adds another twist to this...if you accidentally cut a structural member, the "gravity resistance system" of the roof will already be compromised.

    I agree with everyone else here, get on the roof, cut your vent and get the hell off the roof!
    ‎"The education of a firefighter and the continued education of a firefighter is what makes "real" firefighters. Continuous skill development is the core of progressive firefighting. We learn by doing and doing it again and again, both on the training ground and the fireground."
    Lt. Ray McCormack, FDNY

  9. #9
    Join Date
    Dec 2001


    Roof Cutting:
    Lots of questions about vertical ventilation and cutting the roof in particular. Let's discuss from my point of reference.
    Vertical ventilation (some form) is always an important tactic at fires in structure with a few exceptions:
    High Rise (more than 70 to 75 feet)
    Peak roof platform construction private dwellings (except if skylights are installed)
    Structures in which there are fumes of some gas. At least until you are sure that the gas is lighter than air (only 9 in the world)

    Next there is a big difference in "Opening the building vertically" And "Cutting the roof"
    I have been to a lot of fires and the conservative ration of opening the roof and getting below to a second truck tactic AND beginning to cut the hole is about 100 to 1 - extremely conservative.
    So when do you prepare to cut a roof (take the saw!)
    1. When fire is under the roof! (simple huh?)
    1a. When the fire is in a one story building (one story buildings - the fire is always in position under the roof)
    2. Queen Ann (Victorian - balloon constructed large area private dwellings.

    If you are the roof team member - Take the saw if the fire is in the top floor, reported in the top floor, suspected in the top floor, or you are ordered to (until you change the policy)
    Take the tools (halligan hook and halligan tool - choice) and get there and open what you see and get off. Leave the saw in the compartment.
    Simple job that we love to complicate

  10. #10
    MembersZone Subscriber NB87JW's Avatar
    Join Date
    Feb 2002


    I am in total agreement with the others. The only time we might cut a hole and leave it is when it's an "inspection" hole that isn't expanded to a vent hole. This might be done because it's too close too the fire or too far away.

    "Making Sense with Common Sense"
    Motor Vehicle Rescue Consultants
    ( MVRC@comcast.net) Jordan Sr.

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