What Exactly is a BEAD of FIRESTOP?
If you have been following this blog, then at this point you are well aware that the annular space is the gap between the penetrating item and the rated assembly. We have also mentioned several times that when there is NO gap it is considered point of contact. Did you know that the firestop needs to be installed differently when there is no annular space than when there is? It makes sense if you think about it. If there is annular space, many firestop details will require 5/8” of sealant be installed INTO the annular space. If there is NO space in which to install the firestop, many installers simply smear the firestop sealant over the top of the rated assembly. When they do this, it is not always obvious that there is point of contact. The installation can easily appear compliant if destructive testing is not conducted. The reality is, however; that the installation does not conform to a tested and listed assembly and in a fire scenario it there is a risk it may fail prematurely. Unfortunately, many installers are not even aware of the liability they create when they do this. It is a bit of a catch 22, if you will. If the inspectors do not catch this mistake, the installers assume that they are doing it right. The jurisdictional inspectors bear no liability for missing this during an inspection, however the new building code requirement calls for third party special inspectors in high-rise and risk category III and IV buildings. These inspectors would likely be liable for missing this during an inspection. The firestop installers certainly would be liable, because they are the ones who are supposed to assess the firestop assembly before the installation. They are the ones who are supposed to know the details they themselves submit.
So, if you are installing or inspecting these firestop installations, what should these point contact locations look like?
First of all let’s be VERY clear that point contact and continual point contact are two different things. An example of continual point contact is when a 1” pipe or conduit is put through a 1” opening. There are very few firestop details that allow for continual point contact. When a firestop detail says annular space can be 0”-1” that generally means that a 1” pipe can easily be installed in a 2” opening. If the pipe is concentrically installed (centered in the opening) then the 1” pipe in a 2” opening would give you apx ½” annular space all the way around the pipe. If it is off center then the annular space would be different on either side. If it is all the way to one side of the opening then the annular space is 0”-1”. The firestop detail will typically call for a bead of firestop at the point of contact. It will also define the size of that bead, so lets take a closer look at what is expected in this case.
Most of the penetrants will pass through the rated assembly at a 90-degree angle. If we remember our geometry classes from way back in middle school, the hypotenuse is the face of the triangle immediately opposite the 90-degree angle. In the diagram below, it is marked as C. When the firestop detail says that the bead of sealant needs to be ½” it means that the hypotenuse must measure ½”.
Now, at what point is the bead supposed to start or stop? This is not clearly detailed in any requirements but my personal opinion is that if the firestop installation calls for ½” of sealant to be installed INTO the annular space, the bead should be required in any space that the required ½” of sealant cannot be installed. This is not a standard. This is not a requirement. This is just Sharron’s opinion, so take it as that. Adopt it as your own if it makes sense. If you disagree, please let me know your argument against it.
On the other hand I have seen inspectors that require that if a bead is installed, it shall be installed all the way around the penetrant. I disagree with this because I feel it encourages installers to complete continual point contact installations and just throw the bead around the entire penetrant.
If there is no tested and listed application for continual point of contact, it should not be allowed. Here are a few examples of continual point contact details. These are the only times it is acceptable to have continual point contact. You will note they are all 1000 series details, meaning metal pipes. WL1054 is an example of a metal pip through a gypsum wall and CAJ1673is an example of a metal pipe in a concrete or block assembly. Please look at item 3, where you will see it allows for continual point contact and will require respectively a ½” or ¼” bead of sealant. Now you know what a bead of sealant should look like and how to measure it properly. Remember it must be tooled to ensure it sticks both to the substrate and to the penetrant. In the case of these two details, please also know that these two manufacturers likely have details that could utilize a more cost effecting non-intumescent material. It should be noted that BOTH of these details need to be done with intumescent firestop and not the less expensive products.
So with that, let me know what you think. Do you agree? Do you disagree? What do you see in the field?
Thank you for taking the time to learn a little bit about the industry in which I work. If you have questions about any of this don’t hesitate to reach out to me. In the meantime, keep learning and continue to make projects better.