Firestopping Penetrations in Rated Shaft Walls- Are You Getting it Right? Part 2

Welcome back to our discussion about firestopping shaft penetrations. With this post we are looking into the question of how do you properly firestop penetrations in a shaft wall assembly. First we will look at block wall assemblies. For the sake of this discussion we will assume these are shafts where we have no reasonable access to the inside of the shaft. Clearly, this will exclude stair shafts because in this condition typically we have access to the inside of the stairwell as well as the outside where the rooms would be located. For the sake of this discussion let’s say we are talking about a mechanical shaft so the penetrations might be 1) bare metal pipe 2) plastic pipe 5) insulated 7) ductwork. If you think my numbers are not in the right order please look at this post so you understand why the numbers are in perfect order. Looking at these different penetrations will help you maneuver through firestop submittals much faster, so please become familiar with the UL nomenclature.


If you have any questions or comments about the importance of knowing the nomenclature or asking for submittals feel free to contact me.


So let’s start with the easy stuff first. We know that wall applications have to be protected on both sides for the simple fact that we do not know which side of the wall the fire could start on. This makes it complicated because we don’t have access to both side of the wall in this case. If you have been following this blog post or if you have just now reviewed the link above, then you know the UL listed details we need to look at in the submittal will be either CAJ1000 or WJ1000 details.


My guess is, that what you need will be found in the WJ details because the CAJ details (as you know) can be used both for floor applications and for wall applications.


I’m a dinosaur in this industry (almost 20 years yup I’m a dinosaur- and yes I started when I was 12…LOL) and since I no longer work for a firestop manufacturer I don’t get updated on the new wiz bang details. I had to do a little digging to find you some examples of relatively new details that are perfect for this type of application.


You may have heard me say “I don’t have a favorite firestop manufacturer” so don’t think that because I should you use brand A that means they are the best. The best solution for any application is one with a third-party testing agency standing behind the applications as opposed to 1) the guy in the field “wingin’ it” 2) an engineering judgment.


That said, here is a perfect detail for your metal pipe through a concrete or block shaft wall: 3M’s WJ1108. This is not the only detail, other manufactures have a similar test, but since this tested system exists; I would suggest that jurisdictions not allow the use of an EJ for the simple fact that tested and listed details should trump EJ’s any day of the week for the simple fact that it that has not been tested.


Can you use this for a wall where you have access to both sides? Certainly, but whether you have access or you don’t, be very careful that this is installed properly. Both of these details require 1” of sealant. If you don’t have sufficient annular space then this installation will be difficult to properly install. If you are responsible for special inspection (or even the standard AHJ inspection) you may want to ask to be on site for several installations so you can be sure they install the mineral wool in a way that it is recessed 1” from the outside edge of the concrete. Clearly, if they don’t do this then they cannot install the required 1” depth of sealant.


Imagine you have ¼” annular space. Now, picture trying to install 1” of sealant in that space. It will be easy to make it look good when the installation is complete but it will be a challenge to do this right. As an inspector or part of the QC team, it’s your job to be sure its right. If you have any questions, contact us.


So, let ‘s move on to the gypsum shaft walls. In this case you know that we are looking at a WL1000 series detail. So first take a look at this detail, WL 1222 


If we are going to install the firestop in stages as the drywall is installed, this means we will firestop the shaft liner before the outer layer of drywall goes up. So, does WL1222 work for this? Please take a moment to look at the detail and think about this question.


Have you looked at the detail and considered the question? If you think you can use this WL1222 for a shaft wall, I will tell you that you can’t. Go back to the detail and see if you can find out why? Tune in Wednesday to this blog post and I will share the answer with you.