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How Do We Handle Fires In Lighweight Construction Buildings?

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  • How Do We Handle Fires In Lighweight Construction Buildings?

    After spending a week in Indianappolis for the FDIC and having some more exposure to the workings and dangers of lightweight construction, what should we consider when we fight these fires? Should the approach become exterior only or do we still take the risk and fight them with interior attacks and do searches? Will thermal imaging help us identify failure potential sooner? How do we vent the roofs, or do we vent the roofs? I would like some insights here on what your policies and thoughts are regarding lightweight construction.

    The information presented herein is simply my opinion and does not represent the opinion or view of my employer(s) or any department/agency to which I belong.

    [This message has been edited by M G (edited 03-09-2001).]

  • #2
    If there is a life hazard in the building, we are sworn to do our best to protect and rescue those who are in harm's way.

    If the building is empty, with an unknown burn time or heavily involved, surround and drown. I cannot justify putting personnel in harm's way to save a basically disposable building.

    Just my .03 worth...Captains have to pay a little more!

    Firefighters: rising under adverse conditions to accept the challenge!
    Captain Gonzo

    [This message has been edited by Captain Gonzo (edited 03-09-2001).]


    • #3
      I don't know if we can apply a blanket policy to all light weight buildings. My guess is it's all going to come back to size up when your rig pulls up. What is the current fire volume and it's location in the building? What is the roof load? Is this a restaurant like McDonald's with HVAC units on the roof and kitchen blowers adding a large amount of weight therefore increasing the odds of failure of the structure?

      Running neck and neck with size up, is pre-incident preparedness. Current construction methods are continually increasing the need to preplan all of the commercial buildings in your response area if not on whole neighborhoods.

      Good question, I'm curious to get some other's input.


      • #4
        I am very interested in this topic. And have a few questions to add.

        1. What do you consider lightweight construction?

        The old saying, "They don't build them like they used to" is so very true. Today, there is a big focus on preserving our natural resources. This has led to some excellent advances in building construction, such as wooden I-joists, wood trusses, and SIPs (Structural Instulated Panels - Which are a sandwich of OSB, foam, and then OSB). While these are excellent for builders and homeowners, they pose a problem to the fire service.

        2. What is the fire service doing to adapt to these new types of construction?

        I have worked as a carpenter building multi-million dollar homes, and cannot rememeber the last time we built one without the wooden I-joists or trusses. As you can see, these new types of construction are so beneficial that they are being used in expensive and cheap homes and it is becoming a standard practice as well.



        • #5
          GREAT post MG,

          Lightweight construction scares the sh*t out of me! It is something we are currently debating with our rural board. We have asked them for a small Quint Arial. They have denied it saying that we have no need for it. I guess it is going to take a vent team going through the roof to wake them up.

          Fire Load is something to consider, affected areas though are going to be tough to sight unless obvious.

          I'll just stay in the background and let Cpt. Gonzo and all his fellow officers tell me what to do.

          BTW- Cpt. Gonzo. I hope they give you enough of a pay increase for that .03. I can barely afford my .02 with as much .02 as I tend to put out!:-)

          Your Brother In The Service,
          Rob Herpel
          Vice-Pres./Asst. EMS Coordinator
          Fremont Rural Fire Department


          • #6
            We didn't build it and we didn't set it on fire either. Lightweight construction or TRUSS if you will, is no reason to get you or your people killed. Known Life hazard, I will make a try. Otherwise its a writeoff. My people go home at the end of the day. It's my job to make sure that they do. I will not place my people at risk for a fast food joint that they stapled and taped together and will put back up in a week.


            • #7
              Indeed MG this is a great subject. I've noticed lately though that many fire service professionals who have fears about lightweight construction - ie collapse apply the lessons learned from the Florida Hallmark store, the McDonalds to houses and 4 plexes.

              Working both construction and fire service for a number of years, I just don't see the danger of unanticipated catastrophic collapse in these occupancies. Along the same lines, I don't see the point in vertical ventilation or roof operations very often.

              In almost every case where a room and contents fire on the top floor of structure vents the window, there will be extension through the soffit. (A pet peave of mine, I can't believe the local codes here don't require firestopping above the window in the soffit). As the attic begins to become involved or even if it is well involved, in my mind the quickest and safest way to vent, confine and extinguish is to PPV and enter the structure and remove the ceiling from below, starting in the hallways, doorways.

              What are the rest of your thoughts.



              • #8
                Corvin, follow this link for a report on the Fort Worth, TX church fire where we lost three. There are several other links on this page to similar incidents.

                This details an unanticipated catastrophic collapse. If you download the PDF report, the front cover has a close-up picture of the lightweight truss roof with the metal plate peeled away from the wood. It's very scary. In this scenario, vertical ventilation was critical to the success of the crew inside. This was an extreme and a terribly unfortunate incident, but it shows that it does happen. I'm with John Ford on this one. If there's no one inside, and there's a decent amount of fire showing, forget it, it's not worth it. Stay Safe.


                • #9
                  Thanks PA for the info.

                  I guess I feel the info you provided reinforces my previous post. The structure in question was not a residential unit with "average" size room subdivisions. I agree 1000% that lightweight truss construction in commercial spaces that involve larger openings are deadly. Again, the Florida Hallmark fire, Hackensack, McDonalds, this Texas church all were larger span spaces.

                  I am still interested in examples of fires where lightweight construction collapsed castrophically into room spaces averaging 120-350 sq feet. ( I don't doubt that they have happened, I'm just not familiar with any and would like to discuss them).

                  Also in the texas church fire it 'seems' that the crew performing rooftop ventilation had as near a miss as possible. I continue to believe that truss roofs, esp truss roofs with involved attic spaces are no place for vertical ventilation. Access to the fire will be safer and quicker from below (two story open spaces & cathederals would be a good example of where it wouldn't be quicker)

                  Be Safe


                  • #10
                    A quick post. Reading my previous comments maybe I didn't do a very good job at making myself clear. Commercial/large span lightweight construction is very dangerous under fire conditions and I am very concerned.

                    My comment was that I am hearing people say 'that 1500 sq foot ranch has a truss roof- it's too dangerous to enter'

                    or just the other night

                    'this four plex has extension into the attic, lets set up the ladder tower' (the entire two story unit including two separate but attached garages (single story) on opposite ends were even destroyed.)

                    Lightweight is relative to size, span, fire loading and occupancy usage.



                    • #11
                      I think there's a lot of good comments here. You have to evaluate the building and what it is you can save.

                      Not only is there a difference in the span and weight supported by the roof of a 1500sq ft ranch house vs. a 3000sq ft. McDonalds, but also the McDonalds lacks life hazard or intangibles like business records to save. The house is much less likely to collapse, and at the same time may have life hazard, and almost always has intangibles that insurance can't replace, like family bibles, photographs, and your last seven years tax returns.

                      Larger residential lightweight buildings and commercial/religous buildings pose a much tougher problem for the Chief to balance what can be saved vs. the risks of trying to save them.

                      To simply write off a building because it is "lightweight construction" would include just about every building built in my town since the early 60s. And the great majority of those built before the 50s are either post & beam or balloon frames with there own set of problems created by massive, interconnected void spaces.

                      Take four "lightweight construction" buildings from my town -- a 1200 sq foot 1970 era ranch house, a 60,000 sq foot 4 story fully sprinklered *including* a dry pipe in the attic Elderly Housing complex, a 3000 square foot McDonalds, and a 100,000 square foot shopping center with metal trusses. There all lightweight, but they also all have distinctly different hazards and tactical needs.


                      • #12
                        Corvin, thanks for clarifying things. I'll agree with the commercial vs. residential light-weight construction. I guess a universal definition for light-weight construction would help to facilitate discussions. I define light-weight construction relative to the purpose that the construction is meant to serve. A wood truss roof for a car dealership, McDonald's, church etc. is light-weight relative to the size of the structure and the purpose that it is meant to serve. It can not withstand any considerable amount of heat stress due to the stress that it is already under. A wood truss roof on a residential building however, can withstand more heat exposure since it is not under a tremendous amount of stress to begin with. So, to make a long story even longer, I think we all agree and are on the same page now. It's all relative, and each situation must be evaluated separately. Stay Safe.


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