Firestopping Hollow Core Concrete- Part 1

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
  1. Min 4pcf mineral wool
  2. Ceramic fiber blanket
  3. Concrete
  4. Grout
  5. mortar

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.