When installing a radon mitigation system, fire safety usually isn’t top of mind. However, it’s important for mitigators to ensure that radon systems do not interfere with fire-resistant structures. Today we’ll discuss firewalls, firestop collars, and proper installation.
What is a firewall?
Firewalls are fire-resistant walls that reduce the chance a fire spreads from one portion of a building to another. In radon mitigation, we usually run into firewalls when running pipe through the shared wall between a house and an attached garage. When drilling a hole through a firewall to run a pipe, it’s important to maintain its integrity with a firestop collar.
What is a firestop collar and how does it work?
Firestop collars have intumescent material that expands up to 60 times when it’s exposed to heat. In the event of a fire, the material in the collar will expand to close off the opening left by the pipe, preventing smoke and flame from entering the home. However, for a firestop collar to be effective, it must be installed properly.
How to properly install a firestop collar?
Let’s say you’re running a 3-inch pipe through the wall. The outside diameter of the pipe is 3 1/2 inches, and you want to have about a quarter inch of smoke sealant around the pipe. You would cut a 4-inch hole through the sheetrock and a 3 5/8-inch hole through the rim joist. You could also drill a 4-inch hole all the way through and put a backer rod just beyond the back side of the sheetrock.
Next, use smoke sealant to seal around the pipe, at least the thickness of the drywall. The smoke sealant will prevent smoke from entering the house around the pipe.
After the pipe is sealed, it’s time to place the firestop collar. The firestop collar should go over the pipe, not over a fitting. In the event of a fire, the fitting may fall off, which would leave an opening in the firewall.
Now it’s time to fasten the firestop collar to the wall. It must be secure enough that when the intumescent material expands, it will not push the collar off of the pipe. When screwing into wood, use a number 8 wood screw and a 1-inch fender washer to attach the firestop collar.
If you have drywall, which is common when going through a ceiling, use a toggle bolt and a 1-inch fender washer.
If going through the block, use concrete anchors to secure it to the wall.
Firestop collars may seem like a minor detail when installing a radon mitigation system, but it’s a vital step for keeping homeowners safe.
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