Fire Caulk Fail

Irving LaRue

Irving LaRue

Member
Location
Warrenton, Virginia
Occupation
Electrician Apprentice
Electrical apprentice working on my first ever attempt at fire caulking a large gap. After much mess and frustration, this is where I left off. I can’t help feeling like there must be a better way to do this than rockwhool, tubes of fire caulk and cardboard box scraps.

What are your suggestions? Are there any materials you’d use instead? I’ve seen some people use a putty type substance that scoops out of a bucket. I’ve seen others use fire caulking bricks. What would you have done here?

Thanks for the help!
 

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That's a fairly common sight in firewalls across the country. Yours looks better than most.

I opt for putty over caulk every time I get a chance. If you have some remodel skills in your blood you can patch in some drywall to narrow the gaps. Related to that, you can make friends with a drywaller and tip him twenty bucks if he throws a little tape and mud over your holes while doing some other work close by.
 
rc/retired said:
I believe that the building codes "shall require a qualified person install fire caulk, etc" JMHO

Ron
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The last ten years before I retired I always opted for a Fire Proofing contractor unless it was a small project.
 
Hilti does make a fire rated foam that can be used on fire rated walls, but it's super expensive and I've never seen it. You aren't finding it at Home Depot.

The orange "fire rated" spray foams are one of the biggest misrepresentations in the industry. They cannot be used on any wall or assembly with a rating in hours. The only thing that stuff can be used for is to fill a hole for the purpose of stopping airflow that might direct a fire into a concealed area where it can spread through the building. I encourage you to spray some of that foam out and apply a blow torch to it for a minute after it dries and see how well it burns - it basically becomes napalm.

To properly apply a fire stopping solution, you MUST have the system sheet from the fire stopping manufacturer, or you have absolutely no hope of getting it right. You cannot just buy a tube of caulk and some mineral wool and start stuffing and caulking away until it looks right. You might pass inspection if the inspector is not doing their job, but the install will never work as intended.

For most in the industry, especially an apprentice, what I just said is a total pipe dream because the boss, who wouldn't know a proper firestop system sheet if it bit him in the butt, gives you a tube of fire caulk and turns you loose. I can't blame anyone in the scenario except the inspectors who allow it to happen. That's how it went when I was wearing the tools, at least.

If you send me a DM, I have a video I can send you that will get you started on the right track. It's not a simple subject, but it will put you miles ahead in under 20 minutes.
 
Oddly I just read some responses to my sarcastic remark the other day about an ancient invention called a telephone. It is once again, applicable. I have dealt with Hilti, SpecSeal and 3 M tech support phone calls on fire caulking. I was extremely pleased with Hilti and Specseal and not as enamored with 3M.

Anyway, you can call either of these companies who's phone numbers you can get on line. When you describe your situation, they will send you documentation for an approved method of fire caulking. They will need information like the number and type of conduit, wall construction, fire rating, annular space. If there isn't a listed method, they can design a system and produce an engineering judgement that will usually be accepted by the AHJ. A good example of this is that putty pads have only been UL approved for boxes up to 5" x 5" they are not tested with three gang boxes. Hilti will send an engineering judgement that states it is adequate protection. An AHJ can accept that and I have had 3 accept it, or they could reject it and require 5 siding the box, which hasn't happened to me.
 
I retired from a large hospital where us guys in facilities along with all contractors were only allowed to use one brand of fire stop. Was a large company that made all different types of fire stop. Every two years every one of the 65 facilities guys had to take a one hour fire stop class where they handed out literature. One thing I learned if we were running a 12/2 MC cable thru a fire rated wall they told us to make the hole big enough to get around a 1/4" bead of fire stop between the admired jacket and the sheet rock. We always had cases of fire stop in a tube but very little putty. Told us the fire stop putty cost four tines more. If we had several wall penatrations we had the carpenter shop apply the fire stop.
 
I know that a lot of the very smart people here know this but a refresher. A "Fire wall", or a "Smoke Barrier" are not "walls" per se. They are Listed assemblies. In most cases UL is the listing agency so I will say UL assemblies. As such, UL tests an assembly consisting of most details and variables, sheetrock thickness, stud material, stud spacing, screw spacing mudding and taping, etc. Once done with that they test hundreds of means, methods and material for penetrating those walls. Each of these methods has a UL number, and any "legal" penetration must follow one of these methods. So, even though people often just squirt some fire caulk in a gap, it MUST comply with a UL listed method. Look here. https://systems.stifirestop.com/ for one very well constructed search engine for an example of these assemblies.

Enjoy and hope this helps those of us who don't deal with this regularly. It is important. If you don't think so, watch the movie Towering Inferno which is loosely based on a fire in the MGM Grand Las Vegas where improper fire walls caused a fire to spread to multiple floors in the 1970's or 80's, I forget which. (that is if my memory and what I read is true).
 
Thanks for the help, everyone! I’m very hungry to learn and would like to be a foreman/ project manager someday, so all this information helps.

As for fire caulk experience, I’ve done plenty, but never a large gap like this. It’s always been 1-2 pipes in a home with small enough gaps that it filled easily. This was my first large penetration and I had way more issue than I realized I would.

I caulked a second hole that these pipes passed through and it turned out MUCH better. I can’t figure out how to post a picture of the second hole, but I’ll upload them if I do. I plan to return to this hole here and caulk the middle portion after the outside is dry. On the second hole, I started from the inside and worked out, which went much better.

I have never heard anyone mention UL listings for these types of penetrations or fire caulk contractors. I was just given a couple tubes of caulk and a sheet of rock wool with no further instructions. I actually did a better job on this than my foreman did because he attempted it first. So it’s the blind leading the blind in this case.

I’m going to reach out to my superintendent when I have a chance to ask him about penetrations like this. He’s not often available so here is a faster way to get a response for a lowly apprentice like me. The proper channel would be for me to mention it to my foreman than he discusses with the PM or super, but that isn’t going to happen. So I have to get my education where I can.

Thanks for the help!
 
This is the second penetration I caulked for the same pipe run. It is passable, but I can’t help feeling like there is a better way than slamming 4 tubes of caulk and rock wool into this gap. I would use fire caulk bricks, but they’re pricey and I’m not the foreman, so that’s not my call. I also would have squared off the hole with painters tape, but we didn’t have any.

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It looks pretty good. Remember that this red caulk expands when it's heated so even tiny gaps will be filled during a fire.
 
At one time several years back the was a fire pad that would stick to inside back of box (didn't have to encapsulate the box just put on the back wall of box) and when it got warm from a fire it would activate and expand and fill the box preventing fire from spreading out of box. Can't remember the product but it doesn't seem to be around anymore.
 
Fred B said:
At one time several years back the was a fire pad that would stick to inside back of box (didn't have to encapsulate the box just put on the back wall of box) and when it got warm from a fire it would activate and expand and fill the box preventing fire from spreading out of box. Can't remember the product but it doesn't seem to be around anymore.
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https://www.3m.com/3M/en_US/p/d/b5005459011/ https://www.hilti.com/c/CLS_FIRESTOP_PROTECTION_7131/CLS_FIRESTOP_PUTTIES_7131/r1575891

There are two of them, STI and others have them also.
 
Strathead said:
....

Enjoy and hope this helps those of us who don't deal with this regularly. It is important. If you don't think so, watch the movie Towering Inferno which is loosely based on a fire in the MGM Grand Las Vegas where improper fire walls caused a fire to spread to multiple floors in the 1970's or 80's, I forget which. (that is if my memory and what I read is true).
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I don't think so. The Towering Inferno was released about 6 years prior to the MGM Grand fire. As I recall the fire did not spread to multiple floors, but smoke and toxic gasses did, and that was the cause of the large number of deaths. The biggest issue was a common return air plenum above the fire area that was separated from the fire area by plywood. When then burned, the smoke entered the common plenum and spread into to the high rise hotel area.
 
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