angle

This is a liability that we find on most large projects. Would we find it on yours? (Part 4)

We have been discussing the fact that larger non-insulated non-dampened ducts are often not firestopped correctly.  We have discussed the problem, the resolution and how to identify the documentation to ensure the resolution is correct.

Someone recently asked me how this could be missed for so long and by so many.  The answer is simple, no one reads the details closely enough to know.  Combine that with the fact that inspectors are overworked to the point that they don’t have time to read every firestop submittal.  If the inspector doesn’t tell you it’s wrong, then you assume it must be right.  That makes sense and you can’t blame the installers for thinking this way, anyone would.  You can’t blame the local inspectors, because they are overworked and have a lot on their plate every day.  Sure, there are probably a few lazy ones here and there but as a general rule, the inspectors I’ve met all want to do their job and do it well.

On a union jobsite the mechanical contractors install the duct.  The insulators come in and firestop around the duct and they think their scope of work is done..except it isn’t.  The last step on the UL listed detail, that their company submitted for the project, requires this angle we have been discussing. But the insulators union guys can’t start installing angle without treading on the tin knockers turf.  No one bothered to tell the tin knockers they needed to install angle.  This is by NO means a knock on the unions; because you will find the same problem on non-union job sites, except then in some ways its worse. The non-union shops have no excuse for not completing the scope of work required in the UL listed detail.  They are not treading on anyones turf.   This is one more reason you need to make sure you hire competent contractors and competent inspectors.

So, with the advent of Third Party Special Inspection for Firestop, one would hope these common issues would be remedied.  My fear is, that too many people who already do third party special inspection of other elements on the job site will readily accept firestop inspection work without understanding what all is entailed to inspect the installations.  Do they walk the site with the firestop submittals?  Do they look at every point in the UL details?  An inspection firm should not accept this scope of work without truly understanding it.  If they are on site to do other testing, it makes sense they would accept this additional scope.  It makes it easier for everyone involved because they only have to call one contact for all the inspections.  If the inspectors are not well trained, then they will not be able to pick up on the seemly small issues that, as you now can see from the last three blog posts, is not a small issue at all. Instead it is a liability for all involved.

Check out this blog post for a simple question you can ask of your firestop installers or even your third party special inspector.  It’s one simple question that allows you to know that they have a basic understanding of firestop essentials. Tune in for future blog posts that will give you even more questions to ask. https://halpertlifesafety.com/key-questions-for-your-firestop-installerinspector/

If you missed our other blog posts, please review them here. Part 1, Part 2, Part 3,

In the meantime, keep learning, keep doing better and help us continue “Saving Lives for the Life of your Building!”tm

Please let us know if you have any questions or comments or if you want to be notified when we have new blog postings.

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Halpert Life Safety Consulting LLC’s

“Saving Lives for the Life of your Building” TM

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.

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.

If you missed our other blog posts on this topic, please review them here. Part 1, Part 2, Part 4.

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

“Saving Lives for the Life of your Building” TM

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.

This is a liability that we find on most large projects. Would we find it on yours? (Part 2)

Last time we talked about the requirement of angle on non-insulated non-dampened ducts.  This time we will talk about WHY it is required. For the sake of easy calculations this time we are talking about a non-insulated duct that is 24″x48″ and running through a 1 hour rated assembly.  It doesn’t matter if it is a block or gypsum wall or even if it is a floor, the requirement will be basically the same.  The one exception is, that a floor is firestopped from the top side, so angle is required on the top side.  A wall will require both firestop AND angle on BOTH sides of the wall.

This is a big liability for your company, if the angle is not installed and today we will talk about WHY this is so important.  If there is a fire, you are pretty much guaranteed that your firestop application around the duct will fail if your 24″x48″ duct does not have retaining angle properly installed.  There are a few things we have to explain. First, is how assemblies are tested.  Second is about buttons on shirts. Third is a painless physics lesson dealing with the Coefficient of Linear Thermal Expansion. Fourth we will tie it all together for you.

Testing Assemblies:

ASTM E119 allows everyone to burn something and compare it something else using very specific criterion.  This way you can ensure that materials will perform as expected in a fire scenario.  This is one of the standards that is used for any of this firestop stuff we are talking about,and much more.  One section of the test is a “time  temperature curve” that details what temperatures must be reached inside the test furnace at specific time intervals. The temperature at the 1 hour mark its required to be 1700F.  Why am I telling you this?  It will make sense in a moment.

Physics of Buttons:

If you are wearing a button up shirt that only has two buttons and you pull on each side of your shirt; there will be a considerable gap between the two buttons.  How much of a gap will depend on how hard you pull and how far apart the buttons are.  If you have more buttons on your shirt, say six buttons; then rather than have one big gap you will have a series of smaller gaps between each button.  Stay with me now, on to a physics lesson and then we will relate your shirt buttons to physics and back to firestop, I promise!

Coefficient of Linear Thermal Expansion:

What happens when you heat something up? Many things respond the same way (at least prior to ignition).  They expands, right?  But how much something expands depends on three things, the initial temperature, the end temperature, and the coefficient of that item, in our case steel ductwork.  So, if we have a room that is 70F degrees  and we look only at the duct length of 48″ and we go back to the ASTM E119 time temperature curve that is used to test firestop, then at 1 hour the temperature in the furnace will be 1700F.  If you ran the calculations then a 48″ duct will expand to become 48.9389″. The formula is below if you want to play with it.

Pulling it all together:

So, the same way that your two-button shirt has a big gap, the duct with no retaining angle will have a gap because the extra length, created by the expansion, will have to go somewhere.  This movement will cause the duct to bow inward, because it can not bow outward because it is contained by the concrete or the metal framing of a gypsum wall assembly.   The bowing that occurs will (at the apex) create a gap of almost 1”.  Add that to whatever the annular space was before the increase in temperature (which I’m most cases is maximum 2″).   The firestop material required on these UL listed details is intumescent, meaning that it will expand when exposed to significant temperature. However, the expansion will not be enough to fill the void of the combination of the pre-existing annular space as well as the gap created by the bowing duct.  So, the angle is required to prevent this large gap from occurring. The same way the extra buttons reduced the gap on your shirt, but may vary based on the spacing-the requirements for the retaining angle will call for specific spacing and for the screws to go into the duct through the angle.  This creates a series of small gaps with smaller gap apices (yes, I had to google plural for apex).  This creates a scenario where the fire, smoke and toxic gas can not get to the non-fire side of the assembly prematurely.

So, at this point you should be asking about how to install (or inspect) the angle, the screws and the rest of it.

Our next blog will talk about where to find the requirement for the angle and what exactly is required and what you should be looking for so you can confirm that the installation is correct. You can find that here and the following one here. If you missed our first blog posts on this topic, please review here Part 1.

Remember the more you know the better you can be at your job!  Together we all can be part of a movement- “Saving Lives for the Life of the Building.”tm  If you have questions or comments please email us at info@halpertlifesafety.com.  We would love to hear from you.

 

Here is the formula or you can go on line for it.

dl = L0 α (t1 – t0)         (1)

where 

dl = change in object length (m, inches)

L0 = initial length of object (m, inches)

α =  linear expansion coefficient (m/moC, in/inoF) 

t0 = initial temperature (oC, oF)

t1 = final temperature (oC, oF)

Compliments of www.engineeringtoolbox.com

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__________________________________________________

Halpert Life Safety Consulting LLC’s

“Saving Lives for the Life of your Building” TM

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.

This is a liability that we find on most large projects. Would we find it on yours? (Part 1)

The next few blog posts will cover an issue that is often a liability on large projects.  This non-compliant firestop installation impacts the liability for the owner, the architect, the mechanical contractor, the firestop installer and the inspector.

If you have a non-insulated duct that is 28×36 and it is going through a 2 hour rated wall, it will likely require a damper.  The damper manufacturer will require retaining angle be installed on one side of the damper. We could go into the purpose it serves, but that just makes for a long blog and here we are focusing on PASSIVE fire protection. (If you want to know why dampers require angles, please contact any damper manufacturer and they can fill you in.  The more you know the better you are at your job!)

Did you know that when this same duct runs through a 1 hour rated wall and may not need a damper, that it will still need retaining angle?  The angle in this case serves a very different purpose. Walk any job you’ve been on and if you see angle on BOTH sides of a duct through 1 hour rated wall WRITE TO ME.  Take a picture and send it to me!  I hope to eventually be wrong when I say this is an issue that is missed more commonly than not.  I say this because as long as I am right; then buildings are not as safe as they should be.  Our primary goal at Halpert Life Safety is to improve the level of passive fire protection in buildings.  We can only do that with YOUR help.  If we can help you to be better at your job, together we make buildings safer.  Check back for the next post and I will tell you all about WHY this is a requirement and WHERE you can find the documentation, so you can make sure this problem doesn’t happen on YOUR project.

Please write to me and tell me your thoughts on our blog or firestop in your community.  Did you know about this requirement?

If you want to read the next posts on this topic, please review them here. Part 2, Part 3, Part 4.

I’ve been on projects all over the world and it just makes me want to make a bigger difference…to improve the life safety in more jurisdictions.  After all at Halpert Life Safety we are “Saving Lives for the Life of the Building.”  If you have questions or comments please email us at info@halpertlifesafety.com.  We would love to hear from you.

Sign up now for notification of new blog posts.

__________________________________________________

Halpert Life Safety Consulting LLC’s

“Saving Lives for the Life of your Building” TM

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.