Firestopping Hollow Core Concrete- Part 2

In our last post we discussed the firestop requirements for penetrations through hollow core concrete floors, we gave you a few examples of UL listed details that don’t require you to follow the requirements noted in the XHEZ


In the last blog, I said that I hoped you were getting this information in time.


Today, I want to explain why I made that comment. If you stick with us in the next post I will give you some ideas that might help your next project run more smoothly.


First, let me explain the problem you might face:


If your subs have run services half way up your building before they even think about what to do for the firestop installations, how are they going to get back in to the opening and fill those cells with any of the required material.


Here is a refresher of what is allowed:

Any cores breached by the opening need to be filled with min 4” depth of

  • Min 4pcf mineral wool
  • Ceramic fiber blanket
  • Concrete
  • Grout


So, let’s fix this before it becomes a problem.  The first step is DO NOT assume that everyone knows how to do this the right way.  Second step is to have a discussion, possibly at a pre-bid meeting, but certainly at a pre-construction meeting.


In this meeting, you need to make your team aware of the structural concerns related to a hollow core concrete floor, but you can’t forget to talk to them about firestop and here is what we suggest for the meeting.


  • Print out the UL XHEZ document (give everyone a copy)
  • Read the section on hollow core concrete in the meeting
  • Explain what this means to all of your trades by giving specific examples based on the firestop submittals
  • Put it in your meeting minutes in detail
  • Completely review the firestop submittals against the penetrations you will have on the project (see our video series for more on how to do this)
  • Conduct field walks before the trades run their penetrations to ensure the cells are filled if needed
  • Then hold everyone accountable


If all of this sounds like a lot, I have good news.  The easiest way to be sure you have it right, is to hire us to conduct a pre-construction meeting with your team.  We will help get your team on the right page with what is required before they start and we will make a few field walks with the team as the project starts and progresses to be sure we are there to support any issues you may encounter.


If you want to do it right, we are a great addition to the team. Past clients tell us they are stronger on future projects because of what they learned working with us.


We are like a concentrated dose of support. Concentrated- stronger and more impactful because we focus on what we know and we share that with your team.  Clients who have worked with us in the past tell us the look at firestop differently and they believe the life safety of their future projects will always be better because of what they learned when we worked together.  Give it a try and see for yourself!


Our next post will give you a few more things to think about on your hollow core project when we discuss block outs. After that we will also share a few ideas on how to remedy the problem if you are reading this too late in the game.


Please share this information with anyone you think can benefit from it and if we can support your project in any way, give us a shout!


Until then, thanks for taking the time to read through this today.