As always if you have any questions about firestop or passive fire protection don’t hesitate to email me. Just go to our contact page here.
As always if you have any questions about firestop or passive fire protection don’t hesitate to email me. Just go to our contact page here.
I’ve been invited to write for a blog at adhesives.org. This one is on the history of firestop. Check it out.here
Here is a great article by a fellow blogger and fire code junkie. I hope you enjoy. This is appropriate considering a conversation I just had about the Avalon fire here in New Jersey. Cables run unprotected through rated walls and draftstopping after the building was inspected and signed off, was considered a considerable contributing factor in how the fire was allowed to spread rapidly through the entire building.
I will be back with you again soon with more of my own stuff just for you.
For now, I will leave you with Mr. Johnson!
Last post we talked about how insufficient annular space and/or sealant depth can have a major impact on the performance of a firestop installation. We talked about a metal pipe in that scenario, but what if
We are not talking about a metal pipe, but rather an insulated pipe or duct? Then, the scenario gets worse faster. The firestop material required to be used will be an intumescent material.
The tested and listed assembly is going to call out a prescribed depth of sealant that will be required to close down the opening around combustible material or around gaps created in ducts. Read this post if you want more information on this.
If there is just a thin coat of sealant there will not be enough intumescence to close the gap, not to mention that the sealant needs to be installed between the penetrating item and the inside edge of the opening so that the expanding firestop can be directed to close down the gap. Firestop follows the rules of nature in that it moves in the direction of least resistance. If it is sitting on the outside edge of a wall it will expand away from the wall. If it is wedged between the edge of the opening and the penetrating item it will have no choice but to expand towards the gap that is created and fill it before fire, smoke and toxic gases can get through.
Penetrating items can’t always be centered in an opening, so what is the proper way to firestop a penetrating item when it contacts the edge of the opening? Check in to our next blog post for that answer. Until then, keep learning and keep your firestop installers on their toes!
Hose Stream part 3 annular space and sealant depth
Now that you understand the hose stream test a bit more, let’s look at why this information might change the way you inspect firestop. In this segment we will examine two very common errors we find on construction projects. The first is a problem with sealant depth. The second is a problem with annular space, which may actually impact the sealant depth.
As Chad pointed out in his article we shared previously, a thin layer of sealant will not survive the hose stream test. This is why it is important to conduct destructive testing when evaluating firestop installations (both penetrations and rated joints). If the penetration firestop assembly is installed in concrete, there is a good chance that mineral wool is a required backing material. Often, if the installer is not careful how they pack the mineral wool, it will be lumpy. When the firestop is installed over the lumpy backing material the sealant depth will be irregular. It may be thicker than required in one area and to thin in another area. The area where it is too thin can easily be the very spot the hose stream test would fail, if your field assembly were subjected to the laboratory test. This happens both in penetrations and in joint applications where any form of backing material may be used. This is why destructive testing is so critical to ensuring installation conforms to the tested and listed systems. If you are in a jurisdiction where destructive testing is not allowed, I would challenge you to walk the site when the installer is working and check the way they pack the mineral wool before they install the sealant. If it is not compacted uniformly, then the sealant won’t be installed uniformly. If you are going to conduct destructive testing, this quick preliminary walk will give you some insight to what you can expect when you start your inspection. If you are in a jurisdiction that prohibits destructive testing, this can be invaluable to identifying whether or not the installations might conform to the standards.
The next problem we often find is related to the annular space. Let’s revisit the scenario presented when we talked about annular space and continual point contact. We have a contractor who uses a 1” hole saw to make a hole for a 1” pipe. It may sound good, but it’s going to create a problem for a good firestop contractor. The firestop tested and listed assembly will call for a required sealant depth. The sealant needs to be installed in the annular space, which means the assembly into which the firestop is to be installed needs to actually HAVE annular space. Let’s paint a picture in your head of what would happen when a firestop contractor smears sealant around the edge of the pipe to make it look like there is sealant in the right place. Through the life of the building any movement of the penetration cause by pipe hammer, thermal expansion, pipe vibration or anything else would cause this thin layer of sealant to crack or pull away from the wall. Some firestop materials set up rather hard and would crack sooner than other more pliable materials but some form of failure would eventually happen to any material even before subjected to a fire scenario. Now if we take same installation that we have in your head and subject it to the test requirements even before the issues we previously noted have had a chance to occur, the picture you have in your mind should include water coming through the test assembly when it fails the hose stream test. But wait you say, the drywall would stop the water from going through, wouldn’t it? Sorry to say, its not likely. Let’s look at why!
The drywall on the fire side of the assembly is sacrificial and the only thing really stopping the fire is the drywall and the firestop on the non-fire side. Now let’s assume you have a metal pipe, it is going to draw heat through the wall. This will likely char the non-fire side drywall weakening it and creating a scenario where the assembly will fail the hose stream test, so sorry. If you think the drywall will stop the fire in this scenario you are mistaken. It will be brittle and will fail once exposed to the hose stream test.
Next post we will paint a picture that is even more bleak and we will look at how this simple error can create an even bigger problem. If you want to be sure this is not happening on your project, check back and see where we go with this. Until then, keep learning and keep making buildings safer.
Last post you read an excellent article from Chad Stroike of HIlti and this week I want to add a bit to it.
Imagine a room on fire. As the temperature mounts, the pressure inside the room will increase. We want to know that the integrity of the firestop system will be able to withstand the impact of this pressure increase. As the temperature grows metal elements through the walls and floors will expand and contract, twist and contort. They will be hot on one end and not on the other. Thin wires holding lights can snap, leaving the fixture to swing and slam into a rated wall. Furniture or heavy duct assemblies can crash into rated walls. We want to know that the firestop installed in these rated assemblies will have the integrity to withstand these potential hazards without becoming dislodged. This is one more reason for this hose stream test on top of everything Chad mentioned in his article. If you haven’t read it yet, you can get it here.
Something I found interesting when I first learned about the hose stream test, is that it is done half way through the test. This means that a wall or floor is taken off the furnace half way through the duration of the test and immediately subjected to the hose stream test. Picture a concrete floor with pipes or ducts that are red hot. Now picture a 30-PSI stream of water hitting the red-hot pipes and smoking hot concrete assembly. You can imagine the steam engulfing the room and shrouding your vision, the steam hissing in your ear and the smell of smoke choking you. Then, after this segment of the test is completed, you would walk to the “non-fire” side of the assembly and look for signs of water breaching the concrete floor. If there is light coming through the assembly or any sign of water that may have penetrated the floor, then the test assembly has failed. If the assembly passes, this is just one step in the process because the assembly must be burned for the entire duration. This means that many rated wall, rated floor or floor ceiling assemblies are likely tested twice; once for the full duration of the fire test and then often a second time for the hose stream test. This may not be the case for concrete or block assemblies because they don’t degrade as rapidly in a fire and may survive the hose stream test even after the full duration on the furnace. Certainly for gypsum assemblies, the fire side is basically sacrificial. It won’t last long in a fire test, so UL’s requirement is that the hose stream test is conducted at the half way mark of the test (but not more than 1 hour). This means that a 1-hour fire test will have a hose stream test conducted after 30 minutes. A 2-hour test will have a hose stream test conducted after 60 minutes, as would a 3 or 4 hour test.
If you ever get the opportunity to witness the hose stream test, you should. If you are at all a geek like me, you will appreciate the impact it makes on the test assembly.
Next week, we talk more about scenarios where the hose stream can cause a test sample to fail. Now that you have a better understanding of how firestop is tested, you can better understand why certain elements of the tested and listed details are critical to the performance of the assembly and critical elements to be inspected.
I want to wish you all a wonderful holiday season. However you may celebrate it I hope it is better than you could dream. I will be back with you in the New Year to carry on this discussion about the importance of understanding the hose stream test and how this information impacts firestop installations and should impact inspections.
All the best to all of you,
When you look at a UL listed detail that has a 1-hour F rating, what does that tell you? At a very basic level you can expect the assembly was tested and didn’t let fire through for one hour. There is so much more to it than that and once you understand, it might change how you inspect firestop. Keep reading and let me know if it does.
F RATING- as defined on UL website
The F-rating criteria prohibits flame passage through the system and requires acceptable hose-stream test performance. Lets break this into two parts. First it is saying that fire doesn’t breach the assembly during the test period. Obviously, with firestop, we are trying to contain a fire; so we want to know that the rated assemblies will keep a fire at bay for the designated time period which is known as the F rating. A 1-hour rated wall is expected to contain a fire for 1 hour. F ratings for firestop are 1, 2, 3, and 4 hours. The temperature inside the furnace during the test will increase as the duration of the fire increases. For example in a 1 hour test the temperature will be at least 1700F (538C) at the 1-hour mark and 2000F at the 4-hour mark (1093C). Surviving these temperatures is still not enough to obtain an F rating for a rated assembly. There is one more critical element involved in the test procedure called the hose stream test.
HOSE STREAM TEST- what it is and isn’t
I have sat through too many classes on firestop, codes and what not, only to cringe when I hear the instructor tell the class that the hose stream test replicates impact of the fire fighting methods on the fire rated assembly. It is like nails on a chalkboard to me and I can feel it running down my spine. (Yes I am that much of a geek, that it bugs me to the core) By the time the fire fighters are on the scene with their hoses, any loss of life in that area has likely occurred. Property damage is done. Firestop serves no purpose at this point, because the integrity of the assembly has failed and fire has breached the wall or floor. Fire fighting methods are not part of the firestop test. I believe that understanding this critical element of the firestop testing process is integral to the proper inspection of firestop. We will get into this more shortly. In fact, a lot more, because this is a 5-part discussion about why the hose stream test needs to be better understood in order to improve firestop inspections. For now however, I would like to share this article by Chad Stroike of Hilti. Chad does an excellent job explaining the hose stream test, why it is part of the fire test standard and what it is intended to replicate.
I am excited and proud to announce that I will be teaching at Rutgers in 2017. There will be two classes- one on Grease Duct Wrap Installation and Inspection and the other on Understanding the Requirements of Third Party Special Inspection of Firestop. They did not accept my 2 day class on Firestop Inspection and the Common Mistakes because there are other people who already train on firestop. If you are interested in joining one of the classes, please let me know and I will send you the schedule when it is pulled together. Have a great weekend everyone and when you get back to work Monday, be prepared to make a difference!
ANNULAR SPACE- This is a term used only in a discussion of through penetration firestop not in rated joints. It is basically the gap. More specifically it is the distance from the inside edge of the opening to the outside edge of the penetrating item. It is actually a critical and often overlooked part of a firestop assembly.
When measuring the annular space, sometimes it gives a “nominal” measurement. If the detail says nominal ½”, then the tested and listed detail expects the field condition to have a pipe that is centered in the opening. That can happen, and it snows in Las Vegas…sometimes. More often the annular space will offer parameters defined by a minimum and maximum annular space. If the annular space lists 0” to 1” this means that the penetrating item does not need to be centered in the hole. It also means that its okay if the penetrating item makes contact on one side.
This does NOT mean that when an electrician runs a 1” conduit, they can use a 1” hole saw. Some contractors see the 0”-1” and think that the pipe can squeeze into the opening and the firestop contractor can firestop the application. This happens all the time, but that doesn’t make it right. It only makes it common.
When the opening is just barely big enough to allow the pipe through, this creates a condition known as CONTINUAL POINT CONTACT. Another time this can occur is when a 6” sleeve is run for a 4” pipe that will have 1” insulation on it. There is enough room to get everything through the sleeve, but there will not be enough room to install the firestop detail that should have been submitted.
There are very few tested and listed systems that allow CONTINUAL point of contact for a bare metal pipe, let alone for a combustible penetration such as insulation or even plastic. This gap is critical to the proper performance of the firestop assembly. If the tested and listed detail calls for 0”-1” then it assumes there will be some space into which the sealant can be installed. For a typical 1-hour gypsum wall the required sealant thickness will likely be 5/8”. If there isn’t at least ¼” gap, then the sealant depth cannot be achieved. This is critical to the performance of the firestop installation and we will talk more about this in our discussion on HOSE STREAM TEST. We will go into this in depth, but for now we are not finished with the discussion about annular space. How do you measure it?
If there is a square duct in a square hole, measuring the annular space is pretty simple. If it is a round pipe in a round hole, its simple again. What about when you have a round pipe in a square hole? Do you measure to the longest distance, which would be to the corner or do you measure from the edge? According to UL, the measurements should be made to the edge, so basically at a 90-degree angle from the edge of the opening to the side of the pipe.
That covers annular space pretty well for now, but there is more to consider. If you have any questions feel free to reach out to us and we are happy to help if we can. Next up we will talk about the hose stream test. This will help clarify why the annular space is such an important element to verify during a firestop inspection. You will know how a continual point contact installation will likely fail and much, much more. Thank you for taking the time to learn more about firestop. If this information has not convinced you to take a closer look at the annular space requirements during our firestop inspections then the discussion on hose stream test certainly will. Till then…