Last month, we discussed firestop collars and the importance of proper installation. If you missed it, read the article here. Today we’ll show you what happens when a firestop collar is installed incorrectly.
What is a Firestop Collar
To recap, firestop collars are used to maintain the integrity of a firewall, like the shared wall between a house and an attached garage, when running pipe through the wall. If there’s a fire, the intumescent material inside the firestop collar will expand to close off the pipe, preventing smoke and fire from entering the home.
Firestop Collar Proper vs. Improper Installation Performance Test
We wanted to test how well a firestop collar works when installed correctly versus how it performs when it’s not installed correctly. *For this experiment, we ran two pieces of 3-inch pipe through a mock wall. The firestop collar on the left is installed correctly. However, the firestop collar on the right is not. In the picture below, the garage side of the wall faces us. The other side of the wall would represent the house.
Proper Firestop Collar Installation
For proper installation, we drilled a 4-inch hole through the sheetrock and a 3 5/8ths hole through the rim joist. That left a quarter-inch gap around the pipe we sealed with intumescent firestop sealant.
Next, we anchored the firestop collar to the wall with number 8 wood screws that went into the rim joist.
Improper Firestop Collar Installation
For the improper installation, we drilled a 3 5/8ths-inch hole, which was a tight fit. For this one, we did not use any sealant. Instead, we attached the firestop collar with drywall screws that only went into the drywall.
Lastly, we glued fittings to each pipe.
The Test
Now for the fun part. To see the firestop collars in action, we lit a fire under each of them. Let’s take a look at the results.
Proper Installation Results
The greatest difference was how the intumescent material performed. On the proper installation, it worked as intended.
It also sealed the fitting before it fell off.
The properly installed firestop collar remained secure.
Improper Installation Results
On the improper installation, the intumescent material pushed out the side of the pipe.
The force of the intumescent material pried the collar away from the wall. By the end, only one of our three screws were still in place. 
The improperly installed collar did not fully seal the pipe or the fitting.
Side-by-Side Comparison
The proper installation (right) effectively prevented smoke from entering the home. However, on the improper installation (left), smoke came through the pipe and the crevices around the pipe.
With the correct install (right), there was very little damage on the house side of the wall. However, the incorrect install (left) was a different story. The pipe melted, and there was damage to the wall itself.
As you can see, the installation plays a crucial role in a firestop collar’s effectiveness. When a firestop collar is not present or is installed incorrectly, your home will be more susceptible to smoke and fire damage.
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*This experiment was inspired by Structure Tech’s video Not a flamethrower testing on intumescent firestop collar
