We are almost done with our discussion on firestopping Hollow Core Concrete projects, but we can’t leave without sharing the last few common mistakes.

The real problem comes when the subcontractors run their pipes, ducts and cables without knowing that the mineral wool, concrete, grout or mortar is required.  Once these services are run, you are going to be hard pressed to actually firestop the installation properly.   Think about it for a moment. If you have a 7” core through the floor slab and you want to run  a 6” pipe (or a 4” pipe with 1” of insulation) in the hole, how are you going to get 4” of mineral wool into each side of the core (or possibly two cores that have been breached by the core rig.  That is when you are stuck with one of two really bad choices I noted earlier.

One more thing I should tell you before we are done. One AHJ I spoke with read the paragraph from the XHEZ document because he...

Welcome back to our discussion about firestopping hollow core concrete. If you are still with us, then we hope it is because you want to make sure your next hollow core concrete project runs smoothly and that the firestop installations conform to requirements.

The topic today- BLOCK OUTS

When firestop is not part of the pre-construction discussion on a hollow core concrete project, typically the openings sizes cavalierly exceed 7”x7” that you now understand as a typical requirement. This means the opening may not be firestopped without additional documentation.  Larger openings can cause other complications as well because of the unique nature of the floor.  Assuming you can get the necessary paperwork that may not be a big deal. By necessary paperwork we are talking about a listed detail allowing for an opening larger than 7”x7”, or an engineering judgement (EJ) from the firestop manufacturer that is unique to your firestop installer...

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,...

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...

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...

Our last blog post discussed clearance requirements for sprinkler pipes when you are working in a seismic zone.  The NFPA and the damper manufacturers use the phrase clearance. The firestop industry uses the term annular spaceand defines it as the distance from the outside edge of the penetrating item to the inside edge of the opening in the rated assembly.

Firestop applications often refer to a minimum and maximum annular space. This is because most of the times the pipes are not centered in the opening. This is not going to cause a problem with most applications, but when we look at the NFPA requirements discussed in the last post we used the example of an 8” sprinkler main that would require a 12” opening.

If the pipe is centered in the opening the firestop detail will require roughly 2” annular space. This is not typically going to be an issue, but when reviewing the firestop submittals you need to make sure the annular space of the firestop...

Are you building in a Seismic Zone?  If so, are you aware that there is a required clearance around your sprinkler pipes. If you do not meet this requirement, you are risking the life safety of your building. So, if you are in a seismic zone, please ensure your team conforms with this requirement.

Allow me to share a little story with you before we get into the specifics.

I was part of the quality control team on a massive construction project. I had written the build team up, because they did not conform with this particular clearance requirement we are discussing.  The executive team called me into a meeting to explain the information in the report.   I didn’t know everyone in the room, but of the executives I knew, I had tremendous respect for them. My goal has always been to be a catalyst for positive change and you can’t do that if you run around with a chip on your shoulder always having to prove you are right. My...