ITS firestopping by the numbers

May 1, 2005
Follow these six steps to firestop information transport systems.

Follow these six steps to firestop information transport systems.

Early in the morning of November 21, 1980, a fire erupted in a delicatessen at the MGM Grand Hotel and Casino in Las Vegas, NV. As smoke and fire spread throughout the building, 84 people were killed and 679 were injured.

The disaster is considered the second-worst hotel fire in United States history. Its official cause was an improperly grounded electrical wire. Most fire damage occurred in the casino on the second floor and the adjacent restaurant, although most deaths occurred from smoke inhalation in the hotel’s upper rooms. The tragedy jumpstarted concern in the information transport systems (ITS) industry about appropriate firestopping. The subsequent World Trade Center disaster hammered home, at least to me, that something needed to be done.

According to the BICSI Telecommunications Dictionary, 2nd edition, firestopping is “the process of installing listed fire-rated materials into penetrations of fire-rated barriers to re-establish the fire-resistance rating of the barrier.” The Dictionary further defines a firestop system as, “a specific construction consisting of the material(s) (firestop penetration seals) that fill the opening in the wall or floor assembly, and around and between any items that penetrate the wall or floor (e.g., cables, cable trays, conduit ducts, pipes), and any termination devices (e.g., electrical boxes) along with their means of support.”

As ITS designers and installers plan routes for the latest in high-speed communications cables, they must routinely seal penetrations in fire-rated barriers. Many new systems by various manufacturers have been developed specifically for this task. The two key elements of a typical low-voltage penetration system are the intumescent caulk or putty and the method of “bounding” the intumescent.

Intumescent caulk and putty are the active materials of a firestop system, expanding to form a type of insulation within the system to prevent passage of smoke and flame. While all intumescents work about the same way, the key to a successful firestop system is the method selected for “bounding” the intumescent. Bounding can be done with sleeve systems, square or triangular metal boxes, or even chicken wire for bounding putty pillows in a large cable-tray penetration. Many new devices habe been designed especially for the ITS installer, so seek out these manufacturers for training and guidance on system selection.

Professionals in the ITS industry, including designers, specifiers, and installers, must know more than just firestopping theory. If you are involved in the selection or installation of firestopping systems in a building that subsequently has a fire resulting in loss of life or property, you may be liable. You can avoid these issues by using a simple six-step system that I call “firestopping by the numbers.” Make this part of your standard operating procedure for selecting and installing all firestop systems. This approach is completely vendor-neutral, and works well with any tested system on the market.

Step 1 Establish the hourly rating of the wall

Each sheet of ⅝-inch-thick fire-rated gypsum board is rated at a half-hour. A typical cinder-block wall will usually be rated at two hours. If the cinder-block wall is filled with concrete and reinforced with rebar, it could be rated for up to four hours. All barriers are tested in increments of time. Be sure to check the barrier for all applicable ratings, such as fire (F), temperature (T), and air leakage (L).

• F ratings are measured in hours. They indicate how long the system resists flames passing through the barrier, prevents ignition on the opposite side of the barrier, and prevents developing an opening where water could pass through.

• T ratings, also measured in hours, incorporates all the criteria for an F rating plus the firestop system’s ability to limit temperature rise on the unexposed surface.

• L ratings are optional, measured in cubic feet per minute, per square-foot area. They indicate a system’s ability to provide effective smoke stop. The lower the number, the better the L rating. The L rating is determined by a completely different test from the typical burn. It is the first defense from loss of life to cold smoke. The entire firestopping industry, not to mention the population in general, would benefit from the industry spending more time acquiring L ratings for their systems. A good L rating will save lives in a fire, and is at work even before the sprinklers are activated. It can save millions of dollars on smoke-damaged, high-cost equipment, including networks and PBX systems.

Once you’ve determined the barrier’s rating, seek a tested through-penetration system to match or exceed that rating. Manufacturers will assist you with this task.

Step 2 Select and acquire the system's listing

Have your firestop manufacturer furnish you with a hard copy of the Underwriters Laboratories (UL) or other independent test-facility listing. This document is the product of testing that has been performed using the system in the application for which it was designed. It is crucial that specifiers and installers understand that the installation procedure cannot deviate from that which is spelled out in the text of the listing. The authority having jurisdiction (AHJ) will quickly reject any system that is not properly installed or is not within the limitations established in the test burn.

Pay close attention to cable-load limits, fill procedure, and packing requirements (if any). Place a hard copy of the listing in the job file for future reference, and have it on hand for the official inspection. Download the material safety data sheet (MSDS) for the intumescent material you will use to seal the system, and have the document faxed or e-mailed to you along with the specifications sheet for the job and the job drawings. Keep them all in a file at the job site or in your office for easy retrieval when the AHJ asks for them. (I recommend that you keep the information on file in your office. You never know when a building you have worked on will catch fire.) Be prepared to prove that your work was within specifications.

Step 3 Plan the installation

After you have established the hourly rating and selected a tested system, pay close attention to the allowable percentage cable load, which usually is found in the section of the manufacturer’s literature that references “cables.” Usually, the firestop manufacturer defines a percentage for minimum and maximum allowable cable loads. Do the math or seek out the manufacturer’s cable-load charts. If you are not sure of your calculations, seek the manufacturer’s help.

Carefully follow instructions on packing (mineral wool batt insulation) and sealing the ends with the required manufacturer’s firestop caulk or putty. You might consider the possibilities of adding cables at a later date by futureproofing the penetration. Do not, however, make a hole any larger than necessary. A large hole is much more difficult to seal than a series of smaller holes. Also, never mix or match components of a tested system.

Step 4 Seek preapproval from the AHJ

Obtaining AHJ preapproval is a crucial, not-to-be-missed step in the firestopping process. Most of you are rolling your eyes as you read this, but in three words: just do it. At the outset of the job, learn the inspection schedule and proper authority. Seek out the inspector and submit your system’s information for preapproval. This is a good step, for several reasons. First, the AHJ will be pleasantly surprised by your request. It is not often that someone in our industry asks permission. Second, if you are convincing, the AHJ will preapprove your selected system and tell colleagues about your professionalism. Remember also, it is not approved unless the AHJ says it is.

If the AHJ approves your selected firestop before you start the job, all you have to do is install it within the limitations and guidelines provided in the listing. Find or create your own “AHJ request for consideration form.” Submit the form to the AHJ, along with the listing, specifications, MSDS, and supporting documents.

Step 5 Follow the manufacturer's assembly instructions

Cable-load limitations are the most commonly violated portion of an installed through-penetration system. Pay close attention to the tested system’s limitations and consult with the manufacturer when the situation requires a deviation. Many manufacturers can perform an engineering judgment to cover you if your deviation is minor or cosmetic, and if it will not interfere with the firestop’s function.

Our industry has alienated many inspectors in the field, and many of them are out looking for low-voltage contractors who are violating the fire barriers in their respective jurisdictions. Inspectors today will require you to seal the entire barrier once a violation is caught. A few words of advice: never argue with an inspector. It will bring you only grief and may be a career move in the wrong direction. If an inspector wants the system to be painted purple, you should have just one question: “What shade?” Then call the manufacturer to explain what happened and have the manufacturer make recommendations to appease the AHJ.

Step 6 Digitally document your installed system

Label and alphanumerically identify each penetration system with an indelible marker so you can maintain the systems you install. Many systems will come with documentation/warning labels that you can fill out and adhere to an adjacent wall. Be sure to take a time-dated digital photo from a short distance away, as well as a close-up of the label. Submit these photos to your customer as firestop certification. Keep a time-dated version on your computer. Others may use your penetration system in the future and, in the process, overfill it or otherwise negate its value. You may have to produce photographic proof for an inspector who calls to discuss a violation.

The photos also can be used to justify the expense of proper methods. ITS installers should get compensated when they have protected a building’s occupants and property. If you are proud of your firestopping efforts, there is no hesitation on the part of the building owners or tenants to pay you for your effort.

Firestopping by the numbers is the result of issues that have arisen over several years, from hundreds of projects and meetings with architects, designers, engineers, inspectors, installers, and project managers. Firestopping an installation can seem complicated. Following these steps will help ensure a safe job, no matter which manufacturer you use.

MIKE TOBIAS is chief executive officer of Unique Firestop Products (, and a member of BICSI’s Codes Committee.

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