Understanding more about HOW firestop is tested will help you understand what is important when inspecting it. It will help you understand how firestop installations can fail when they are not installed properly. This series will address a wide array of issues while discussing how firestop is tested.
If you want to understand firestop and why certain requirements are important then you need to understand how firestop is tested. You could dig out the standards from ASTM or UL and read all about the process for firestop tests. But, that is a bit dry. So, this will be an attempt to explain how firestop is tested without getting dry and technical. There are a lot of pieces to this puzzle so bare with me as we discuss each one. Along the way you will also garner a better understanding for WHY all this stuff matters. This will be a series of interconnected posts that will loop back into each other and connect with former posts so you can skip what you already know or beef up on things you may want to know more about. Let’s get started.
WHY: Why do we test firestop? The basic answer is to ensure safe installations and to keep all the various manufactures on the same playing field and playing with the same rules.
If you want to create a firestop material and have any hope of selling it in the US, you have to first have it tested by a third party testing agency. There are a number of companies who will do the test, but the lions share of the through penetration tests are done at Underwriters Laboratories. There are more and they include such as Omega Point Labs, Warnock Hersey and others. Having a material tested by a third-party testing agency means that each manufactures material will be subject to the same type of critique and will have to meet the same expectations in the test burn. This means that the end user can have the same expectations of any product installed according to the details in the tested and listed documentation. Understanding why certain elements of a test are important requires you to know more about HOW things are tested. Here is a start to the explanation:
Here are some basics:
Rated floor or wall– the assembly is built, allowed time to cure, set on the furnace. The assembly is peppered with thermocouples’ connected to computers so they can make sure the non-fire side of the assembly doesn’t get too hot. There are specific requirements to how they are placed. You can read more about if you wish by digging into the actual test requirements. We wont get into those specifics here other than to say that the edges of the assembly are not really considered important to this particular test because they are covered in the test for rated joints. This test assembly will be tested for an F rating and for a T rating.
The F rating is the time it takes for fire to breach the assembly. If you are testing a gypsum wall for 1 hour and fire breaches the wall before 60 minutes then you will fail the test. If it breaches at 61 minutes you have at least passed for a one-hour assembly. The T rating is a bit more complex, but still very important. We will save that for our next blog topic, so don’t forget to check in with us next week.
The technical term for this is to ensure that the F rating equals the T rating. There is a whole other topic that needs to be addressed which is the hose stream test, which is an important part of the test and again warrants its own blog post to come shortly.
Rated Joints– the test for the rated joints is basically the same as the test for the rated assemblies, but with a few additions. Now, we are dealing with two different assemblies. The way they are connected will provide the “code required” continuity of a rated assembly. So, if you have a floor joining a wall and they are both rated, we want to know that the joint between the two assemblies will be capable of withstanding the same rigors as the two assemblies independently. The tests are similar but there is one added dimension for many joint assemblies. (note we are not talking about Perimeter Containment/Edge of Slab firestop)
Joint assemblies can be either static (no expectation of movement) or they can be dynamic. Dynamic joints are subject to very specific movement criterion (another topic for later) the joints also require that the F rating and the T rating are the same, meaning that significant amounts of heat wont pass through the rated joint. This expectation will make more sense once we post the information on T ratings shortly.
Through Penetration- As you might expect, the test for through penetrations is very similar to the test for rated assemblies and rated joints. The differences are that we don’t have the T rating requirement. The T rating is a measure of thermal transfer (how much heat goes through the assembly). If you have a copper pipe running through a concrete floor the heat will be on the non-fire side of the assembly very quickly because copper is an excellent conductor. Therefor the T-rating requirement is not in the test standard but rather in the building code (you guessed it, a topic for later discussion). These through penetration tests often have a requirement that the penetrant be rigidly supported. This causes problems for the firestop installer in some cases, but causes even bigger problems for the long-term impact of the firestop if it is not complied with. This is a common deficiency in firestop installations.
If you have attended one of our training seminars or if you already know a bit about firestop you may be thinking…she didn’t even mention the hose stream test. This is critical to understanding why certain elements of the firestop listed assembly are so critical, such as sealant depth, annular space and other topics, but it also helps you understand how various drywall patch applications would not survive the laboratory test conditions AND you guessed it- it’s a topic for another blog post!
So we have basically set the groundwork for the next few months of posts. I hope you take the time to write in and let us know what you think and what else you think we should include. If you need help on a project don’t hesitate to contact us. We are happy to help you improve the level of life safety on your building.