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  1. #1
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    Default EEWs, Drywall, and Laminated I-Beams

    A question for any construction experts out there. Our town has a large number of homes with walk-out basements with living quarters and living rooms in these basements. A preponderance of these are constructed with laminated I-beams as the floor joists, covered with drywall. The windows are typically energy efficient windows. My question is this--does anyone know of any correlation between the time it takes EEWs to fail and the time that heat/fire penetrate the drywall enough to cause a collapse hazard in the laminated I-beams? Or how about regular windows? My question is based upon sizing up a structure, knowing that it is probably built with these features, and seeing fire blowing out of a basement window and deciding whether or not to committ forces for a quick attack/rescue, or just leave them out and drown it. Anyone who has knowledge on these things would be a big help....


  2. #2
    MembersZone Subscriber ullrichk's Avatar
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    I use I-joists in my off duty job. I don't like them, but they are an economic reality that I have to accept. In detached single-family residential applications there is no requirement to "protect" the construction. You are likely to find any number of penetrations through the gypsum board. Assume the structure is compromised by any fire beyond the incipient phase. After that it boils down to risk vs. reward.

    I'm afraid that we have entered an age of disposable buildings.
    ullrichk
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    Push for a sprinkler law.
    The wood I beams or "silent floors" are fine until they catch fire. Their just isn't enough meat to prevent them from an early collapse.
    The drywall, will provide protection, but in a single family you will not be able to prevent homeowners from creating openings.
    It will be hard to place a time limit on interior attack. U of I conducted fire tests on floor assembilies and had collapse in under 5 minutes of fire exposure. You may have to change tactics and attack from the burning side, safely outside. then evaluate and move in for the mop up. It is not a position I envy, if you have the resources try building a burn room and see for yourself how it holds up.

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    Question

    What type of sheetrock is being used. We've seen a promising trend in our area, with contractors using all Type X Fire Rated sheetrock. This when properly applied to a ceiling creates a one hour fire barrier. So one could non-scientifically conclude that it should take about one half an hour to penetrate one side of a wall or ceiling assembly built to the one hour standard.

    Without training, proper size up and good tactics, you can be sure that the fire has an advantage over us when the building was built using lightweight construction materials.

    I don't agree with a blanket "No Go" policy when lives may be endangered. Certainly a cautious approach or marginal attack, but to write off citizens who live in houses built of lightweight construction is a failure in our mission. In the next decade I'll bet that more than 50% of our population will be living in buildings utilizing trusses, glu-lams, and wooden I beams. This will make our job even more dangerous.

    It is time for the NFPA and BOCA Codes to do something for us as firefighters. Require the marking of buildings utilizing these dangerous material so that we can make better educated fireground desicions.

  5. #5
    MembersZone Subscriber ullrichk's Avatar
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    Originally posted by RFDACM
    What type of sheetrock is being used. We've seen a promising trend in our area, with contractors using all Type X Fire Rated sheetrock. This when properly applied to a ceiling creates a one hour fire barrier. So one could non-scientifically conclude that it should take about one half an hour to penetrate one side of a wall or ceiling assembly built to the one hour standard.
    Your scenario depands somewhat on how you define "properly applied." If I'm not building a firewall or using gypsum board as draftstopping/fireblocking I just punch a hole and go. You pretty much have to penetrate for plumbing, electrical, HVAC, etc. so there is no real fire resistance that you can bank on.

    Additionally 1/2" on walls and ceilings is the norm in my area. I believe it takes 5/8" Type X to meet the 1 hr rating.
    ullrichk
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  6. #6
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    I saw a report once, can't find it now. But from what I remember single pane windows go at about 700 degrees double pane gas filled windows fail around 1500 with only the inter pane going exterior pane will fail shortly thereafter. Triple pane argon filled windows generally will not fail from heat.
    A one hour fire rating means nothing unless you know the heat release rate of what is burning in the protected area. I work as an electrician for my days off and I wouldn't trust any residential fire wall/ fire break. Look at the structure and make an evaluation by observing the fire and smoke conditions you see.

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    Though I do not have any evidence, my suspicion is that Glulam would not fail under fire conditions much faster than a similarly sized piece of dimensional lumber. Glulam is not lightweight construction material by any stretch. Rather it is a way to use smaller pieces of dimensional lumber to make up for the lack of big trees to feed the mills these days. I would be interested to see any tests or observations under fire conditions. I can recall one fire where there was a very large ridge beam still intact though the roof and most of the rafters in that area were completely gone. I don't know if it was Glulam or not but I suspect it might have been because of the vintage of the house. But the charring made it impossible to tell just by looking at it....

    Birken

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    Birken,

    The joists being refered to here are the wooden I joists. They look like a steel beam, with a 2x4 on the top and bottom and an OSB web in between.

    I think the glue lams would hold up in the same way as dimensional lumber because of their mass. My only question would be the rating of the epoxy holding it all together.

    Dave

  9. #9
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    Billy Goldfeder's website www.firefightersclosecalls.com has a slide show about a fire involving wood laminated I beams...

    Frank Brannigan says it best...

    "the building is your enemy...know your buildings!"
    ‎"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

  10. #10
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    I'm not sure about in the US but here in Canada there are many different sizes of the I- beam floor joists. Depending on the span and weight load they may measure 1 1/2" all the way to 4" on the top and bottom cords. Add to that the fact that one reason these are now used is that mechanical contractors may cut holes in the mid-span of these joists to run their wares. The hole size is predetermined by the manufacturer and they say where and how many holes may be cut. Check out the web site trusjoist.com. These are one of the major manufacturers of this style of floor joists.
    I've been a journeyman sheet metal worker for 13 years in Canmore Alberta Canada and 90% of the buildings I've worked on, residential and commercial, has been built with these products. I've cut many a hole in these joists according to manufacturer specs. ONLY THE I-BEAM JOISTS NOT THE GLUE LAMS!!!
    Only when I got involved with the fire service 5 years ago did I give it much thought. I am now NFPA 1001 certified, and as of a month ago full time on my dept. and these building scare the bejeezes out of me.
    That being said though if you think of how they are constructed the theory is they are stronger than dimensional lumber. Dimensional lumber, as good as it may be, has inherent flaws in it. As it ages it dries, shrinks, twists, cracks, etc, etc. These I-Beam joists do none of the following. They have no weak points IF THEY ARE NOT COMPRIMISED. It all depends on the quality of the sheet rock intallation and other protective barriers.
    In Canada our 5/8" drywall is only rated 45Min. We also have a 1/2" type X that is rated in the 30Min range.
    In either case if that drywall has been comprimised, I wouldn't think of going in much past 5 min.
    We had a fire here in a building that was under construction here during the summer, no drywall up yet, but the house was ready for it, they were to start loading the drywall into it the next day. The house collapsed within 8 min of start. Not a good prognosis.
    Anyway, check out that site for the TJI joists, hope I shed a little light on the subject
    Dominique

  11. #11
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    I have been doing some research on these things related to fire resistance and have not had too much luck so far. However, one of the known problems with older OSB boards, which is used in the vertical webs of these beams, is that the glue holding the wood chips together degrades under high temps. Basically, the board falls apart when it gets too hot. I believe newer OSB board uses "better" glues, but how much better?

    It is a pretty simple equation, mass = fire resistance. Less mass, less resistance. That coupled with the likelyhood of the resin in the OSB failing under heat, in my opinion, makes a collapse much more likely.

    You need to preplan, that is the only way you are going to know what is out there. I would stay off these floors and out from under them. I had an instructor at last years Firehouse Expo advocating the use of piercing nozzles with minimum entry into the building on basement fires when you know you have an I beam floor. Sounds like a good idea to me.
    Thomas Anthony, PE
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    Paramedic / Rescue Tech North Huntington Twp EMS
    The artist formerly known as Captain 10-2

    No, I am not a water rescue technician, but I stayed in a Holiday Inn Express last night.

  12. #12
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    Default Windows vs. Wood I-Joists

    I've seen many fire tests through my job regarding the pro's and con's of windows and wooden I-joist when subject to fire. Trying to make a comparision is difficult I best, but I'll give it my best.

    Energy efficient windows are designed to stop leakage of the interior conditions to the exterior. This is peformed by stopping the convection of heat through the window. This works both ways (in --> out, out --> in). By the composite (multi-layering) of the window, it takes a greater amount of heat (both intensity and duration) for the exterior window to fail. To that end, the amount of heat contained in the fire compartment (in your case, a walk-out basement) is increased which adds to the second problem....

    Wood I-joist is a composite of wood pieces and an adhesive. The industry found out that, since the strength of a dimensional wood member distributes (cross-section) its load in an I pattern (top, bottom, center strip), it is more economical to develop wood members in a simular shape. However, the 'up and down piece' (web) is normaly constructed of OSB-board or so other composite, using wood pieces mixed with glue and pressed together. The problem? The heat of the fire banking at the ceiling with the I-joists coupled with the increased time of an unventilated fire has been tested to show a failure from 20% - 50% compared to dimensional lumber (such as 2 x 10's). At least you have some gyp board to protect a little bit, which is not the case in almost all unfinished basements utilizing this construction.

    Conclusion: Window failure should not be used as an indicator to determine the stuctural stability of floor systems! The windows will make it all the way to flashover or until you open the door. Side note: Folks in Hurricane areas that have updated building codes can multiply the issue more with multi-layered window construction.
    "The light that goes around, even up-side down".

  13. #13
    Forum Member Fire304's Avatar
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    I don't know about the I-beams, but I ran into a fairly new window at a structure last year that was still intact. Orders were to blitz the room (offensive master stream ops) prior to the entry team going up the stick. I put the tip of our tower right up to the window and hit it with +/- 800gpm from less than 2 feet away, figured it was hot and the force of that much water would blow it right in, nope son of a bitch held for nearly 5 minutes before my team punched out the window with a hook.
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  14. #14
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    Smile I-beams

    I haven't done an experiment with dry wall yet but I found that Just the I-beams themselves exposed to direct flame contact usually fail anywhere between 8 and 12 minutes. I just depends on the load and size of the I-beams themselves but they do not hold up very well at all.

  15. #15
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    Default Lam beams

    The OSB used in the webs of these beams are used because they are able to acheve a "structural rating". Plywood and particleboard are not. Combine this with the overall low cost, and the builders are going nuts with this. I have heard of AHJ's allowing OSB for decking and letting the rafters go to 24 in centers.

    The big issue with OSB is a real world issue. Low mass, high heat absorbsion, early failure.

    I spoke with a guy recently who did some "unscientific" experients on a piece of a beam.

    They suspended it in the air in a kiln. The placed several bricks on top of it. They slowly raised the temp stopping at several intervals and found that it failed before it reached 300 degrees F.

    The formaldehyde used in the glue offgasses so quickly, it fails quickly.

    Also, the I-beams are great for normal "up and down" forces, but do not react well when the load shifts to odd angles. Think of a normal firefighter, gear and crew walking on the floor. I don't really care what floor, there will be some movement. Floors that use these beams WILL move, thereby allowing forces in a "non-normal" method.

    I have not heard of putting gypsum on the sides, but I like it a lot. It should help with some of the failing issues, but it will give a fire another place to "hide".

    I attended a flashover simulator at the Houston Fire Department training grounds. They use a shipping container to demonstrate the point. The fuel (if I remember correctly) was a total of 5 sheets of OSB cut up or in suspension. Granted the container held heat better than most rooms, but the point was made to me in a matter of minutes.

    Just my 2 cents...some say it is overpriced.

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