New Definitions for a new understanding of firestop

You can Google all sorts of definitions you will need when you are talking about firestop. The problem is, now you now the meaning of the word, but you still may not understand the impact what that means in a fire scenario. This definitions section is going to focus on, not only the definition of the word, but also on the reason it may be important in a fire test condition. The hope is that this will help you take a closer look when you are inspecting these various elements of the firestop assemblies. We will give you a new word or a new concept every week and each one will be intended to change the way you may be inspecting firestop. If you know firestop it may not be a new word, but hopefully you will see the word in a new light. Let us know if we have changed the way you inspect.



Intumescent basically means to expand. So if you play rugby and catch an elbow in the mouth while getting tackled to the ground, your lip will intumesce and you will have earned your post game beer. (If you need to explain this to someone else, feel free to insert any sport analogy you wish as long. As it ends in some sort of facial contact and you will get the same image.) The difference with firestop is, that instead of a blow to the face as the catalyst for the expansion, we are looking at heat from a fire. Instead of blood rushing to the area to create swelling, we are dealing with a chemical reaction that causes the materials to enlarge, expand and fill any voids created by combustible materials or movement during a fire.


So intumescent material is all the same, right?



Different sealants will expand at different rates and at different temperatures because they are made with different chemical combinations. A basic intumescent sealant will not expand any where near as much as a wrap strip. Some wrap strips will perform differently than others. In fact, some manufacturers have different grades of wrap strip. These will perform dramatically different. Some will require more material some will require less. Some will cost more and some are considerably cheaper.


When inspecting firestop it is critical that you make sure that the material shown on the tested and listed detail that was submitted and approved for the project, is the same thing that is being installed.


If you are the inspector you may think I’m crazy or you may be cringing thinking of all the paperwork you would have to carry. When I train installers I tell them flat out, that if they want to look better than their competition, they should post a copy of the submittal on every floor. Then when the inspector had a question, the answers were right there for them. When the installer had a question, they knew where to do for the answers as well.   Here is a hint- if your firestop installer doesn’t have a copy of the submittals on the floor where they are working, then this means they are not looking at the details. If they are not looking at the firestop details, how do you expect them to be installing something that conforms to these same missing details?


Next week we will discuss annular space- we will talk about the gap and when we are done you may have another reason to change the way you inspect.  If this was useful, let us know.