This is a liability that we find on most large projects. Would we find it on yours? (Part 3)
If you’ve stuck with me this far, I’m going to lighten things up for you a little and just tell you a story today:
I was responsible for quality control of firestop on a rather large project. I had written a stack of non-compliance reports calling for retaining angle on all sorts of ducts in the podium area of the building. The podium was HUGE and we had a few mechanical contractors on board. They were all in a meeting and one of them brought up the topic of “these bogus non-compliance reports”. I was called in to the meeting and one of the mechanical contractor said “I’ve been doing this for 40 years and I’ve never done this and I’m not going to start now just because it’s what YOU want. It’s not in the codes, its not in the specs and I’m not doing it!” I wanted to say “Congratulations, you’ve been doing it wrong for for a really long time!” but that would not have been productive. At the end of the day my job is all about getting it done right handpicking fights isn’t going to help towards that goal. So, I explained all the information you’ve hopefully read in the last two blog posts. One guy who still didn’t believe he needed to do it said, “You show me the code section that say I have to and I will eat my hat.”
I told him, “711.3.(I forgot the 1.1 in the meeting) Fire-resistance-rated assemblies. Penetrations shall be installed as tested in an approved fire-resistance-rated assembly.”
He griped that, “That didn’t say nuthin about any angle on any duct.” So, I asked him if he put angle on dampered ducts. He said, “Of course!” So, I asked, “Why, there is nothing in the code that specifically says you have to install angle on a duct, so why bother.” He of course said, “It in the manufactures installation instruction.” I said,” Exactly! for firestop you have installation instructions but you also have UL listed assemblies that give much more detailed information and if you look at any 7000 series detail (the UL designation for misc-mechanical), the last line will give the requirements of the angle when they are needed.” and I showed him a UL listed detail that had been submitted by his firestop installer. It read:
C. Steel Retaining Angles – Min No. 16 gauge (0.059 in. or 15 mm) galv steel angles sized to lap steel duct a min of 2 in. (51 mm) and to lap wall surfaces a min of 1 in. (25 mm). Angles attached to steel duct on both sides of wall with min No. 10 by 1/2 in. (13 mm) long steel sheet metal screws located a max of 1 in. (25 mm) from each end of steel duct and spaced a max of 6 in. (152 mm) OC.
You MUST refer to your submitted and approved firestop details. Different details may require different screws or different spacing. One more thing to note, if the annular space around the duct is 2″, the leg of the angle against the wall needs to be 3″. If the annular space is only 1/2″ the leg only needs to be 1-1/2″. Also note that if the duct is smaller, the angles are not needed. You must refer back to the details that were submitted for your project to know if they are required or not required, and all the specifics that go along with it. If you want to know how to find information in a UL listed detail quickly, read this. Also remember this is for non-dampered, non-insulated ducts.
Is there another topic you would like to see discussed here? If so just let us know and I will see if I can get it into the rotation for you! Keep learning and keep doing better. -Maya Angelou “Do the best you can until you know better. Then, when you know better, do better.” Together we all can be part of a movement- “Saving Lives for the Life of the Building.”tm
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Halpert Life Safety Consulting LLC’s
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Our mission is to make a colossal impact on the level of life safety of your building and on the talent of your people. We provide consultation, training, quality control and third party special inspection related to firestop and passive fire protection. We consult for the building industry in the New York/New Jersey (NY/NJ) metropolitan area, as well as across the United States and internationally.