Perimeter Containment- Firestop Joints. Who is Up for a Challenge? –part 2 of 2-

Posted on 2/28/2018 11:44:13 AM By Sharron Halpert

Our last post set the groundwork for a challenge for you. Before we get to the ideas I want to share with you, let’s make sure you understand why protecting this space is so important. 

When I was an intern, working for Hilti, I was given an obtuse project.  Learn whatever you can about the exterior facades on buildings. This task, lead me to a GANA conference in Vegas.  The Glass Association of North America conference was about 500 guys, one other woman aside from this crazy intern who knew nothing about fenestration (crazy intern- that would be me). 

One speaker made it obvious that the fenestration industry knew as little about firestop as I knew about their industry.  He argued that, because of the frog effect there was no reason to even bother firestopping this space.  He said that if there was a fire on the 5th floor, the fire would lap up the outside of the building.  The combination of winds and fire dynamics would quickly break through the glass on the floor above, allowing the fire access to the upper floor.  Granted this discussion took place in 1999 and the understanding of the industry has changed dramatically since then, in fact now this firestop location has its very own test standard ASTM E2307. 

This was a pivotal moment in my firestop career. I found my self torn between speaking out and being timid in a room full of people who have been in their industry much longer than I.  At this point, I had been working in firestop for all of maybe 4 months, what did I know?  For those of you who know me, timid doesn’t sit well with me. While in my head I was debating whether or not to speak up, I found my arm was straight up in the air and as soon as the speaker called on me I had started dislodging the idea he had so carefully begun to create to support why protecting this space was a waste of time. 

I began – Imagine a 30-story building, and as you said the fire starts on the 5th floor. If there is nothing in that space, smoke and toxic gasses quickly spread to the upper floors through the stack effect.  It will endanger everyone on the upper floors and begin to spread down. No one will know the fire started on the 5th floor, so the first responders will be getting conflicting reports from scared people.  As the fire rages and the heat rises, these spaces above can be subject to flash over more rapidly than without some means of slowing the spread of the fire. Not to mention, the fire will spread to the floor immediately above even faster without at least something to slow it. 

Now, imagine there is something in this space. Yes, the leapfrog effect will not be able to protect the 6th floor, but at least it will only impact the ONE floor above and not all of them. While this solution is not perfect, it is certainly better than the nothing this guy was proposing.  

Folks, that was the moment I realized I was passionate about firestop.  I can’t tell you how many people came up to me after grateful I clarified how and why this area was so important, and I was “just an intern”. 

Now, you know why protecting this space is so important, and from our last discussion you know how it is currently protected.  Now, let’s combine mechanical engineering and origami together with special coatings and whatever your imagination can come up with, to create something that is difficult to goof up.  The right combination of materials have the potential to replace not only the protection required at this slot location, but also the array of expansion joints seen on larger projects. 

Break out your mechanical engineers hat for a moment and think about things that are designed to expand and contract without any deleterious impact on the device.  

                  (click to enlarge)

Double cell honeycomb blinds, desk lamp arms, and an array of amazing origami creations can all expand and contract over and over again. 

Jacobs ladder

Even a simple Jacobs ladder you may have made as a kid, works on the mechanical principle of a double hinge.  Any of these contraptions will allow movement needed in this slot or in a standard expansion joint for that matter.  

Next, figure out how to get this contraption to stop fire. All it will take is something  similar to the intumescent coating used on steel that we talked about in this blog

This is a combination of an acid, which is typically phosphorous based and a carbon source.  This magic combination, when heated to temperaturesjust below 400F, will expand and create an insulating char, capable of protecting structural steel.  I wonder if it could be used to coat one of these mechanical contraptions and protect the occupants of the upper floors of a building.   If not this phosphorous carbon combination, what about a graphite mix that is often used in firestops intumescent materials. We talked about these materials in this blog.

Once you have figured out these two elements, you have to come up with a way to secure this contraption to both the concrete floor and the exterior façade.  Oh, and did I mention that you have to get this contraption of yours to pass the requirements in ASTM E2307?

One last thing to consider; if you can find a way to make this installation watertight,
You may capture an even greater market share. If you come up with something, 
please let me know.

Leapfrog Effect
ASTM E2307