Fire Stop Installer Tips: Do’s and Don’ts When Firestopping

Why is it Important to Do Firestopping Correctly?

By Mike Tobias, Unique Fire Stop Products

Firestopping is such a hot issue now because cabling professionals have not been doing a very good job of it. Public safety officials, fire marshals, and building inspectors want us to respect the firewall, which is designed to save lives and property in the event of a fire. In fact, any AHJ (Authority Having Jurisdiction) will require a cable installer to restore the firewall to it’s previous rating before they approve the job. So it’s very important that firestopping is done correctly. However, there is some confusion as to how to properly firestop a cabling installation.

Firestopping to Code

The National Electrical Code (NEC) requires that metallic conduit be installed in vertical penetrations of fire barriers. The conduit sleeve has a fill capacity, usually under 50%, and the resulting void must be filled with fire-dam caulk or putty. There should also be backing for the intumescent material to expand against. (Intumescent material expands in the presence of heat.) Installing cables in a core-drilled floor without the benefit of a metallic mechanical sleeve is a violation of the fire code.

The NEC is less straightforward in dealing with horizontal penetrations of fire barriers: It stops short of calling for metallic conduit, but instead, specifies an ‘approved system’. This can create confusion among low-voltage cabling installers, who may think that a tube of fire-dam caulk is, in itself, an approved system. This is not the case. Approved systems consist of installation guidelines as well as materials, and such comprehensive assembly instructions are rarely found on tubes of caulk.

Firestopping tips:

Here are some practical firestop installer tips to consider when you are faced with firestopping a cabling installation:

  • Does your company have a standard operating procedure for accomplishing this task? If not, one should be established. If you have one, it should be reviewed periodically.
  • Firestopping procedures should explicitly follow manufacturers’ instructions for products such as caulks and putties. There are inherent limitations not found on the package. AHJ Inspectors know these limitations. Don’t exceed them!
  • Before beginning a job, contact the local building inspector and fire marshall to make sure you are complying with the fire codes in your area. Better yet, get pre-approval for your system using our AHJ Pre-approval form found here and on many of our product pages.
  • Use a Metallic Sleeve System  for both vertical and horizontal penetrations of fire barriers. They are the most durable method for firestopping through penetrations.
  • Whatever firestopping method you employ, ensure that all materials and assemblies are approved by a nationally recognized testing facility, such as UL.
  • At the penetration, use indelible ink to record your company name, the date, and the number of cables penetrating the fire barrier. Purchase a disposable camera and take pictures of your penetration next to the documentation. This will protect you if other companies open your firestop assembly and exceed its fill capacity or otherwise violate the fire code.
  • Do not run new cables through existing violations of fire barriers. Some building inspectors will then hold you responsible for all cables in violation of the fire code.
  • Do not caulk or ‘mud up’ around your cables if the fill cavity exceeds the recommended limits. Minimum depth thickness is affected by the space to be packed.
  • Do not exceed the fill capacity of a sleeve. Most caulks and putties are intumescent and will expand to seal the sleeve when exposed to heat.
  • Remember to drill oversized holes for core-drilled conduit. For example, for a 4-inch sleeve, you need a 4 ½-inch hole.
  • Do not use regular insulation in place of mineral wool batt insulation for packing.

At Unique Fire Stop Products, we pride ourselves on providing the best quality firestop products, prices, installer training, and customer service available. Contact us if you have questions about any of our systems.