1. #1
    Firehouse.com Guest

    Red face Imagers and Trusses, Who's your friend?

    I attended a two day lecture series in N.Y.C. last week put on by the F.D.N.Y. and found a common thread running through almost all of the 9 different subjects presented by these guys.


    It seams to be a fact that we in the fire service are looking at a future filled with questionable building materials and construction codes. When you combine the modern volatile fire load of plastics and synthetic materials with structural building materials, which fail quickly and easily under fire conditions, you are left with an increase in firefighter risk.

    Enter the thermal imager. Iím sure our friend from Kentucky will have some input on this subject and I look forward to hearing what he has to say. How are firefighters using their imagers to detect fire in the void spaces created by trusses and other light weight materials. Take a look around your community at anything being built. How much full dimension lumber do you see being used? Around here, very little.

    Hey Scott (S. COOK) Iím sure your tired of telling the story, but did your incident involve light weight construction? What exactly did your imager detect?

    Thereís no doubt thermal imagers are going to help in this area, Iíd like to hear how you guys are going about it.

    I know, a little long winded but this new construction really bothers me and I think it needs to be talked about more.


    Rob Donnan
    Captain, Metuchen FD
    President, Jersey Fire & Rescue

  2. #2
    S. Cook
    Firehouse.com Guest


    Not sure if you could really call it lightweight construction. It was a standard wood/sheetrock (about 12X14) office built inside a metal building auto body shop with shop accessable storage space on top. It appears the ceiling rafters were set on top of the walls as usual and ran the width of the office (12').

    The view through the TIC at the ceiling didn't show any joists/rafters above most of the office area. You could see where some of them came from near the walls, but nothing towards the center of the room.

    Hope this helps and if you need more, let me know.


  3. #3
    Firehouse.com Guest


    Hello All,

    Sorry for the delay, excellent topic.

    No question lightweight construction is no ones friend in the Fire Service. There have been a number of discussions in other areas of the Forum on this particular topic, some very good points made.

    Quick recap:

    You really need to ID where you have lightweight construction in your first due. If it is new construction, chances are it is lightweight. However you also have to keep an eye out for renovation jobs. Knowing what you are getting into ahead of time is a real big part of the battle. In many cases with or without a TI you will not be able to ID the lightweight construction features during the heat of the battle. Architects are doing an excellent job of making this type of construction resemble ordinary construction. Building construction can be your friend if you understand its strengths and weaknesses, you really have to know what you are getting into when you go through the front door or climb onto the roof. If you have not, you really should check out Branniganís book on building construction and Dunnís book on firefighter safety & building collapse. There are also many excellent articles on this topic. There are a number of things you can do without a thermal imager to spot dangerous conditions so make sure you are up to speed on them as well.

    If you have a TI there a number of things you can do. In the past 2 months there have been at least 2 departments that I know of who have spotted an impending collapse and evacuated within minutes before things came down. Their stories will be up on our web site (www.thermalimager.com) and in our next newsletter soon.

    Key things that helped:
    Advanced knowledge that the structure they were operating in was made up of lightweight construction.
    Recognition on arrival by the IC and interior crews that lightweight construction was present.
    Methodical scanning of areas with the TI during advancement that identified high heat or fire conditions in void spaces where lightweight construction was present. This included fire in a false ceiling, fire in a lightweight floor joist assembly, and fire in an attic with lightweight roof trusses.

    In some cases you will be able to actually see rafters or joists through roof, floor or ceiling coverings. However these tend to be the heavier forms of construction, which show on an imager as dark lines when compared to the covering materials. You should obviously take note if these dark lines disappear in areas of high heat indicating they have been burned through. However, in many cases you will not be able to identify the actual lightweight components themselves. Since these components have less mass they can very quickly take on a heat signature similar to the surrounding materials, or ignite and burn away. This is why it is important to know where the lightweight construction is because you will not always be able to actually see the condition of the components in all situations. However if you know there is a lightweight floor assembly and you can identify a high level of heat in that area, chances are you should not be there because failure will not be far off.

    You really need to get out with a TI and take a look at the various types of construction in your first due. Contrary to popular belief you can learn a whole lot looking at structures while you do a pre-fire plan or building inspection, the building does not have to be burning to learn something.

    I do not know of any structure that is worth a firefighterís life. If you can clear the life safety hazard, have lightweight construction, and ID high heat in these areas, get out and let it go. If you canít clear the life safety hazard, scan, scan, scan.

    Also never forget the basics ! Sound the floor and roof, pull ceiling as you go, use roof ladders, and always work in teams. Most importantly make sure the person outside in charge is reading the pre-fire plan or can read building construction and fire conditions.

    Good Luck, Be Safe,

    TI Training Specialist

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