Welcome back to the series where we talk about “stuff we see wrong in the field.” This blog is going to discuss a few challenges we have found with PEX lines in wood framed buildings. If you are working on a concrete project that is using PEX, you should still read this just in case you are making the same mistake. We hope it is useful.
Here is our field condition:
The plumber drilled a hole through the two by fours that are sitting on the plywood floor to frame the wall that will be built. The hole is less than ½” larger than the pex line they are running. This gives them just enough space for the bracket the plumber is using. In the field, they call them mickey mouse ears. I’m not sure what they call them in your area but here is an example of one.
The firestop installer simply smeared firestop around the pex line and covered the mickey mouse ears. It wasn’t until we did destructive testing that we discovered the problem. So, if you are an inspector on a project that is not going to require special inspection, please walk the site before the firestop is installed to see if they are using these things. If they are, you may want to ask a few questions. If you need some help give us a call.
The mickey mouse ears use up all the annular space that you need for the installation of the firestop material. With plastic pipes you typically need to have an intumescent firestop material. This is one that is capable of expanding to fill the void created when the plastic pipe melts away during a fire. The intumescent material can close down the opening and prevent the passage of fire.
Intumescent materials act like most things in nature. That is to say that they move in the area of least resistance. That means if it is sitting on the top of the two by four and adjacent to the pex pipe, when it starts to expand its going to move in the area of least resistance. This will be away from the pipe.
For this reason, the intumescent material needs to be forced into the opening so that the two by four, the concrete or the drywall can contain the sealant as it expands so it is forced into the center of the opening. This enables the material to close down the opening as the plastic pipe softens in a fire and yields to the expanding intumescent sealant.
This is also why, when a plastic pipe touches the side of the opening, its required to have a bead of sealant, which is a build-up of material along the edge of the penetrant and against the rated assembly.
However, when a detail allows for annular space to be 0-1” for example it does not mean that you can have 0 annular space all the way around the opening. If this is allowed the detail should say “continual point contact” and few details do.
There are a few ways to handle this. One would be to not use the Mickey Mouse ears. Another would be to install the firestop first and then force the sealant into the opening as you push the bracket into place. Inspection would be difficult and ensuring proper sealant depth during installation would be imperative.
If you run into this issue, let us know how you handle it.
Thanks for taking the time to read this. We hope you found it valuable. If you did, please leave comments and let us know what other topics you would like to see us address in future blogs. Share this with anyone who can benefit and keep learning. Check back for more in this blog series as we discuss other field issues we encounter.
If you have a Hollow Core Concrete Project- You MUST Read This Blog Series!
Hollow core slabs have a number of advantages, but when it comes to firestop they create a number of challenges that must be addressed BEFORE the project starts in order to ensure a successful project. If you are currently on a hollow core project I hope you are getting this information in time.
If you wait until the pipes and cables are run and then try to figure out how to firestop everything ya’ might be screwed. You might not be able to firestop the penetrations properly in many cases. Realistically you will have two choices. Honestly, you won’t like either of them.
Choice 1: Ignore your problems and do it wrong and create a liability for your company and the people stuck with your building once you leave.
Choice 2: Work backwards, so you can move forward correctly. In some cases this will mean you have to remove the penetrating items first, so you can address the cores in the slab. Another option might be to use a product that you may not have in your budget.
I said, neither choice is a good one. They both suck, right? One creates a major liability and the other has cost implications. They both have a negative impact on your schedule if you didn’t take this into account before construction started. There are a few manufacturers with products that can help, but at the moment I can think of three different manufacturers with products that work for one solution but not another, so you would have to deal with three different sales people to find the best solutions.
I have been in the industry since 1999. Back then you were only allowed to use firestop details that specifically called out hollow core concrete in item number 1 of a UL listed detail. That is the section of the UL detail that lists the information about the rated assembly being penetrated.
That has changed and the details are not so limiting. Now you can use any CAJ or FA detail PROVIDED THAT YOU COMPLY WITH THE FOLLOWING.
- The thickness of the hollow core floor is the same or greater than the requirements of the firestop system
- The opening is not greater than 7” dia or 7”x7”
- Any cores breached by the opening need to be filled with min 4” depth of
- Min 4pcf mineral wool
- Ceramic fiber blanket
For more on these specifics please visit the UL website, right here on UL’s XHEZ.
The only time you do not have to adhere to the requirements noted above is when the listed detail calls out specifically Hollow Core concrete floors AND it doesn’t note these same requirements (see above). One example of this would be with pre-fabricated or semi-fabricated devices such as drop in devices that are similar to cast in place devices or sleeves. We will give you a few examples of these in our final Firestopping Hollow Core Concrete blog post.
In our next blog post I will explain why I hope that you are getting this information in time.
Thanks for joining us again for another video about firestop submittals. Today we are going to touch on a few more things that people often get wrong when pairing the field conditions with the paperwork. Check out the video here and as always if you have any questions please reach out to us here.
We have another video for you today. I gave it a bad title because the reality is, all the information is important, it’s just that most people scan through and miss a lot of valuable information.
If you followed the series on shaft walls you may see where I am coming from. You will have a better idea of what I mean once you see this new video. If you want more information on point contact and annular space you can check out this blog, or point contact, or defining a bead of sealant required at point contact.
After a field walk with a firestop contractor a few months ago I realized that I need to share some information with you about some common mistakes people make when looking at the firestop nomenclature. This video is just the start, we will have a follow up to it as this series progresses. The video today can be seen here. Please let us know what you think of it or how we can help you on your project here.
Welcome back to our firestop submittal video series. Our goal with this is to change the way people on construction projects look at firestop. If you took us up on the last challenge please let us know how it turned out. Today we have a second challenge for you. We got some interesting responses from the last challenge and we look forward to hearing what you think of this one and what the results are. Check out the challenge here and contact us here.
Welcome back. Now that you have a better understanding of how to work your way around a firestop submittal, I want to issue a challenge to you. Check it out in this video here.