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Everybody in the fire service has an opinion, so let me share mine! Have you encountered Q-decking? What did you do? How did you handle it? Let's keep this constructive! - Chris Botti, Owner, RPI.
"Recently I watched a training video of some well intentioned firefighters trying to cut a metal Q-decking roof on what appeared to be an open web metal bar truss roof system. And frankly, there's a real problem with that!
A few months back, we had a fire in the Red Hook section of Brooklyn right behind the quarters of Ladder 131 in a 2 story commercial building in a Fish Smoking Company. Upon reaching the roof, the roofman transmitted that he suspected a Q-decking roof and advised the incident commander and abandoned the roof... why? (Pictures included)
We know that in basic principles in build construction in the fire service, that steel expands 9.5" over 100' when heated to 1000°. (This is typically from a pretty large I-beam) Not only does it expand, but it significantly softens to a point where structural stability is greatly compromised and it becomes prone to collapse. If it can do that with an I-beam, what can it do, and how fast can it do it with a small open web metal bar truss???
The concern is both the Q-decking seams as well as the open web metal bar trusses below the Q-decking...
Think about what you are looking to do here. You're looking to remove the superheated gases as well as allow for any fire to vent out a hole that you are cutting in a roof where typically the height of the roof is 20'+ off the ground with trusses spanning 20' or greater and offset from one another by 4'-12'... and by doing this you a allowing 1000°s+ to go through the "metal trusses" which are typically not fire protected... hmmm. What about that makes sense???
Firefighters have lost their lives as well due to collapses from these types of buildings... do we really need to endanger our guys to cut a 4'x4' or 6'x6' hole in a roof in a 20,000 square foot building??? What is your gain???
I will argue that you can't make a big enough hole, fast enough, to make a difference in fire conditions at the ground level!
Not only are we concerned about the truss below, but we are worried about the seams in the Q-decking and how much is supported in the overlapping of the decking on the truss... at 3am, with a heavy smoke condition with nothing but a few handlights, are you confident that you are going to cut the roof in the right spot and not take the express to the ground???
Don't get me wrong, on a taxpayer roof of traditional wood construction from the 1960's, you can cut the heck out of it! The building construction is distinctly different from that of a industrial/commercial light weight truss building...
Take a look at the 4th picture included in the photos. If you zoom in, you can see the seam in the Q-decking... if you miss that when cutting the roof, you may just dump right into the fire...
There are a lot of people that will say "know your response area!", it's not about knowing you're response area, that's only half of it! It's about know your building construction and how it can kill you...
Just because you may have gotten away with it once, doesn't mean it's correct and should be done!"