Topic: Penetrations through Fire-rated Wall Assemblies
Learning objective: The student shall be able to identify the building code requirements for sealing penetrations through fire-rated wall assemblies.
Two workers are sitting in a bar. One asks, “How big of a hole do you need to make to run three wires through a wall?” The second one answers, “I don’t know. How big are your shoulders?” A bad joke? Yes.
A common problem? Also, yes.
Fire and building officials often find fire-resistive-rated assemblies that have been compromised by electrical wires, telecommunications wires, pipes, ducts, tubes, and other penetrations through one or more sides of the membrane protection. Often, the holes are substantially larger than the item going through the barrier. These holes and penetrations create an unrestricted path for heat, smoke, and other toxic gases to pass through the wall into adjoining spaces, including rooms and means of egress. The results can be disastrous.
The model building codes require that many penetrations through fire-resistance-rated walls be sealed with materials to prevent the passage of flame and hot gases, or be protected by listed through-penetration firestop systems installed in accordance with ASTM E814, Standard Test Method for Fire Tests of Through-Penetration Fire Stops, or UL 1479, Standard for Safety for Fire Tests of Through-Penetration Fire Stops.
The model fire codes also require that these protection methods be maintained.
Firestop systems in wall assemblies must have an F rating of at least 1 hour, and be equal to the fire-resistance-rating of the wall in which they are located. The “F rating” is the time period that the throughpenetration system limits the fire spread during the controlled laboratory testing to obtain its listing. Most firestop manufacturers and suppliers will sponsor local training sessions for building and fire officials to explain how their products work and how to inspect them to verify compliance.
Topic: Penetrations through Fire Resistive Construction
Learning objective: The student shall be able to explain the difference between T Ratings and F Ratings of through-penetration fire stop systems.
When pipes, ducts, conduits, wires or other objects penetrate fire resistive barriers such as walls, floors or ceilings, the openings create a path for heat and smoke to spread through a structure.
The building codes require these “penetrations” to be firestopped with materials that meet the requirements of ASTM E 814, Standard Test Method for Through-Penetration Fire Stops or UL 1479, Standard for Safety for ThroughPenetration Fire Stops.
These documents refer to T Ratings and F Ratings for the penetration fire stop materials.
What is the difference?
• T Rating. The time period that the penetration firestop system, including the penetrating item, limits the maximum temperature rise to 325°F above its initial temperature through the penetration on the non-fire side in accordance with the test standards.
• F Rating. The time period that the through penetration fire stop system limits fire spread through the penetration in accordance with the test standards.
Thus, the T Rating references temperature limits, and the F Rating references fire spread control.
Topic: Through-Penetration Firestop Systems Learning
Objective: The student shall be able to obtain installation details on through-penetration firestop systems.
Today’s picture illustrates a common problem with through-penetration firestop systems: improper installation that renders the system ineffective.
Through-penetration firestop systems (caulk, pillows, protective wraps) must be installed in fire-resistance-rated assemblies to stop the passage of dangerous combustion products and maintain the integrity of the wall or ceiling in which they are installed.
Some of these products involve fairly sophisticated installation procedures that must be followed exactly if the material is expected to act as designed.
Penetrations for pipe, tube, conduit, wires, ducts, and other equipment must be cleaned, properly prepared, and then sealed in accordance with strict manufacturer’s recommendations.
Substituting materials different from the manufacturer’s specifications, or installing the firestop products differently from what the manufacturer requires should not be done unless specifically permitted by a product’s listing.
ANSI/UL 1479, “Fire Tests of Through-Penetration Firestops,” defines the criteria for hourly F, T, L, and W ratings for firestop systems.
F Prohibits flame passage through the system and requires acceptable hose-stream test performance.
T Prohibits flame passage through the system and requires the maximum temperature rise on the unexposed surface of the wall or floor assembly, on the penetrating item and on the fill material not to exceed 325 °F (163 °C) above ambient, and requires acceptable hose-stream test performance.
L Determines the amount of air leakage through the firestop system at ambient and/or 400 °F (204 °C) air temperatures at an air-pressure differential of 0.30 inch (747 microbar) water column.
W Determines the capability of the firestop system to maintain watertightness.
For additional information, go to www.ul.com, and select “Online Certifications Directory.” Type “XHEZ” in the UL Category Code field, and the first document on the list will be an informational guide (“XHEZ.GuideInfo) explaining through-penetration firestop systems.