FCIA Standard Answers to Common Questions Document 1 – Equal F & T Ratings

FCIA Firestop Contractor Members report that Specifications sometimes request equal F and T Ratings on metallic and other penetrating items, joints and gaps with no extra treatment specified by the architect. The purpose of this “Standard Answers” paper is to provide clarification for FCIA Member Contractors and the construction industry about “Equal F and T Ratings” for Firestopping

Definitions – Firestop Systems tested to ASTM E 814 or UL 1479 result in hourly ratings for both flame (“F”) and temperature transfer (“T”). The “F” Rating defines the amount of time before flame pokes through openings to the unexposed side of the test assembly. The “T” Rating defines the amount of time for the surface of the penetrating item on the non-fire side of the test assembly to rise 325F plus ambient temperature.

The purpose of the “T” Rating is to prevent fire spread from the fire side to the non – fire side of the assembly even when no breach in the fire resistance rated compartment exists that would allow flame propagation. Below is discussion regarding the “Equal F and T Ratings” issue that affects FCIA Member Specialty Firestop Contractors regularly:

The 2000 edition of the International Building Code requires equal “F” and “T” Ratings for items penetrating through fire resistance rated floor assemblies. In floor assemblies, penetrations contained and located within the cavity of the wall do not require a “T” Rating. For floor penetrations outside wall cavities, “T” ratings of no less than 1 hour or the required rating of the floor penetrated are. When penetrations are in fire resistance rated walls, there is no mention of a “T” rating requirement. (See IBC 2000 Code for further explanation)

Upon review of the Underwriters Laboratories, (UL) Fire Resistance Directory for through penetration firestop systems, FCIA Member contractors found the following results:

  1. Metal Pipe Testing – In the CAJ, CBJ, FA, WJ, metallic penetrating item series tested systems in concrete floors, concrete and concrete block walls, there are no listed systems with equal “F” and “T” Ratings. In some cases, a “T” Rating of ¼ to 1 hour can be attained in WJ (Walls) systems depending on the system requirements. Insulation may be required to be wrapped around the penetrating item, 2″ thick, extended 12″ past the fire resistance rated assembly on both sides of the wall/floor, in concrete assembly to attain the “T” ratings equal to the “F” Ratings. For wood framed assemblies, there are some cases where equal “F” and “T” Ratings exist. The ratings are available on mainly pipe diameters of 4″ and less.
  2. Plastic Pipe Testing – The CAJ 2000 series plastic pipe assemblies have a significant number of tests where equal “F” and “T” Ratings occur. However, there are a number of tested plastic pipe, through penetration firestop systems where the “T” Rating is less than the “F” Rating.

    Additionally, whenever a metallic sleeve is used in the penetration assembly, the “T” Rating is reduced to “0” hours.
  3. Insulated Pipe Testing – In cases where metal plumbing, or electrical piping is covered continuously with insulation, ratings with “F” and “T” Ratings either less than or equal to each other are available in testing directories. Insulation can either be continuous or partial to attain these “T” Ratings.

    For insulated metal piping, where insulation is not continuous, there are tested systems available. Typically, approx. 36″ of insulation, of approx. 1 – 3″ thickness, depending on the system, installed so that 12″ plus extensions above and below the fire resistance rated assembly is applied to attain a “T” Rating. Consult specific tested and listed systems for details.

    When electrical conduit is insulated to attain a “T” Rating, particular attention must be paid to the thickness of insulation applied and it’s affect on ampacity capacities. Insulation may “derate” ampacity capabilities, limiting power transmitted, and possibly creating a fire hazard.
  4. Cable Testing – Although there is metal used in cable assemblies for wire, conduit, etc., there are some rated systems where equal “F” and “T” Ratings exist. Where aluminum piping is used, “T” Ratings will be higher than harder metals due to the low melt point of aluminum, meaning the pipe will melt before it has a chance to transfer temperature to the non-fire side of the assembly.
  5. Joints and Gaps – All tested and listed assemblies are available with equal “F” and “T” ratings in joint assemblies as the test criteria requires an equal “F” and “T”. In cases where non “insulated” firestop systems are used, “F” ratings may be greater than “T” Ratings. “T” Ratings may be as low as “0” hours.

Based on the above referenced information, it is FCIA’s position that “Equal “F” and “T” Ratings can be provided in some cases. However, Equal “F” and “T” Ratings may not be available in all cases. Architects and engineers shall communicate the need for equal “F” and “T” ratings when required by code for life safety or property protection in construction documents, with specific tested and listed systems referenced to accomplish the ratings.

Due to the limited number of available tested and listed systems in metal pipe applications, there may be engineering judgments or equivalent fire resistance rated assemblies (EJ’s or EFFRA’s) needed to provide the specific “T” Ratings ratings requested.

FCIA Standard Answer # 1 – “Equal “F” and “T” Ratings May 6, 2004 FINAL; Edited August 18, 2018

Firestop Contractors International Association
FCIA Technical Committee Document number 1
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