2012 IBC clarifies fire rated glass and framing applications
This article explains how the 2012 IBC clarifies fire rated glass and framing applications. The ICC recognized that prior versions of the IBC were confusing about fire rated glass and framing applications, so it revised three tables to clarify the codes.
2012 IBC Clarifies Fire Rated Glass and Framing Applications
by Diana San Diego
In 2009, The ICC (International Code Council) recognized that the fire rated glazing (FRG) provisions of the IBC were confusing and appointed an as hoc committee comprised of fire and building officials, test agencies and industry representatives to study the glazing labeling provisions and make recommended code changes. As a result, three tables in the 2012 IBC were revised: Tables 716.3, 716.5 and 716.6. This is significant because, for the first time, the IBC recognizes the difference between fire-protective and fire-resistive glazing and clearly outlines their allowed applications and limitations.
It’s important to note that these are not new code requirement, but rather a clarification of the 2006 and 2009 editions of the IBC. Even though the new tables will not be adopted locally until jurisdictions accept the 2012 IBC, they are useful today in understanding the 2006 and 2009 IBC glazing requirements. The requirements contained in the new tables have been in effect since the 2006 IBC and conform to what NFPA 80 provided in the 1999 and 2007 NFPA 80 editions, which are incorporated by reference in the 2012 IBC.
Table 716.3 – Marking Fire Rated Glazing Assemblies
Table 716.3 clarifies recent glazing label-marking requirements, which mandate that FRG be marked with a letter designation corresponding to the test standard to which the product was tested.
- The letter “W” means that the glazing has been tested to the fire wall test standard (ASTM E-119/NFPA 251/UL 263) and thus is classified as fire resistive.
- Glazing products has been marked “OH” show that the glazing has been tested to the fire window test standard NFPA 257 and meets both the fire endurance and hose stream requirements of the test standard.
- The letter “D” indicates that the glazing product has been tested to the fire foor test standard NFPA 252, and the marking “H” means that it passes the hose stream procedure. The marking “T” means that the glazing meets the temperature rise limits required for doorsused in exit enclosures and passageways.
Note that some products have been multiple markings. For example, if a fire-resistive glazing product has been fire tested both as a wall and door assembly, t will carry a dual marking of “W” and “DHT”. This product can be used in large vision panels in 60- and 90-minute doors. Fire-protective glazing marked only as “DH”, such as safety wired glass or safety ceramic, is limited to 100 square inches in 60- and 90-minute door applications.
Table 716.5 (Revised 715.4) – Opening Fire Protection Assemblies, Ratings and Markings
In reviewing the glazing provisions of the code, the ad hoc committee recommended significant changes to the door assembly rating Table 716.5. For the first time, the code clearly lays out the vision panel size limits and adds a column that specifies the sidelite and transom rating requirements. Importantly, the table distinguishes between the use of fire “protection” rated (or fire-resistive) products. It also makes it easy for the end user to identify appropriate size limits affecting fire-protective glazing, where fire-resistive products must be used if glazing is desired in larger sizes, and where the code would not otherwise allow FRG. The table shown on the previous page is an excerpt from Table 716.5.
Note that 60-minute (1-hour) and 90-minute (1 ½-hour) doors require 60-minute and 120-minute fire-resistive sidelite/transoms respectively. Fire-protective sidelites and transoms are not permitted in this application. Also, 20-minute (1/3-hour) doors in a 1-hour exit corridor require 45-minute fire-protective sidelites/transoms.
Table 716.6 – Fire Window Assembly Fire Protection Ratings
The ad hoc committee recommended an expansion of the information in Table 716.6, a table specifying required fire window ratings. As in Table 716.5, Table 716.6 now clarifies where fire-protective products are allowed, where fire-resistive glazing must be used (e.g., in 2-hour interior walls), and wherefire-protective windows are not permitted. Table 716.6 in the 2012 IBC further clarifies that fire windows are not permitted in 1-hour fire barriers used as exit enclosures or passageways, but are permitted in fire barriers used as incidental use areas and mixed occupancies.
- The marking “NP” stands for “not permitted.” However, there is an exemption. Fire-resistive glazing assemblies tested to ASTM E-119 are allowed.
- “XXX” is a place holder for the fire rating duartion in minutes, which is equal to the fire-resistive rating required for the wall assembly.
Code Change Removes Sprinkler Tradeoff for Doors in Exit Enclosures and Passageways
To repeat, nearly all of the modifications to Tables716.3, 716.5 and 716.6 in the 2012 IBC are intended to clarify requirements and limitations on FRG in effect since the 2006 IBC. These 2012 IBC tables do, however, include one important code change. Previous editions of the code provided for an exception that allowed larger fire-protective vision panels in fire doors used in exit enclosures and passageways when the building was fully sprinklered. The new 2012 IBC removes that sprinkler exception and now reads as follows:
718.104.22.168 Glazing in doors. Fire protection rated glazing in excess of 100 sq. inches (0.065m²) is not permitted. Fire resistance rated glazing in excess of 100 sq. inches (0.065m²) shall be permitted in fire door assemblies, and not ad glass lights, and shall have the maximum end temperature rise of 450 degrees F (250 degrees C) in accordance with 716.5.5.
Section 722.214.171.124 makes it very clear that fire-protective glazing cannot exceed 100 square inches. It further states that fire-resistive glazing is allowed in excess of 100 square inches as long as it limits the temperature rise to 450 degrees F above ambient after 30 minutes of fire exposure. There is no question that fire-resistive glazing meets this requirement.
Note that no fire-protective glazing product can meet the 450 degrees F above ambient after 30 minutes of fire exposure. Therefore, the code makes it clear that it is limited to 100 squre inches, regardless of whether or not the building is fully sprinklered.
The ICC made this change in recognition of the hazards of radiant heat transmission because sprinklersin a buildingfail to eliminate the life safetyand fire spread hazards posed by the unrestricted transmission of radiant heat through large sizes of fire-protective glazing panels in 60- and 90-minute doors, especially when those doors are protecting exit enclosures and exit passageways deemed essential for occupant life safety.
The 2012 IBC tables also clarify that sidelites and transoms around 60- and 90-minute exit enclosure and passageway doors must be fire resistive and rated equal to the wall. These exit enclosures and passageways are intergral to life safety, and occupants need to be protected from dangerous radiant heat levels transmitted through fully glazed exit enclosure doors, sidelights and transoms.
A Cautionary Note about Fire Rated Glazing Listings
One reason why end users are frequently confused about the proper use of fire-protective versus fire-resistive glazing products is the way in which they are listed by test agencies, such as UL and ITS. It is important for design professionals and code enforcement officials to understand that the listing agencies do not list FRG products in accordance with the codes or limitations on their use. Instead, test agencies simply report the sizes and types of assemblies in which a FRG product has been tested. For example, test agencies often list certain ceramic products in 60- and 90-minute sidelit and transom assemblies that are not permitted under any building code in the United States. Accordingly, listings cannot be relied on for determining accepted code applications of FRG products.
When in Doubt, Seek the Manufacturer’s Expertise
Advances in FRG technology over the last 30 years have changed how the building community uses these specialized products. The new generation of clear fire-rated products includes several custon options (e.g. ballistic attack or hurricane defense), reduced UV transmission, noise abatement benefits and various decorative make-ups, affording professionals almost unlimited design possibilities. The codes and testing agencies are working to catch up with technological advances.
Never hesitate to consult the FRG manufacturer if you have questions about product performance, allowed applications, or need help in understanding the code requirements. In some cases, it makes sense to involve the manufacturer in early design phases, especially when dealing with highliy technical products such as FRG. With ever-changing codes and rapid advances in material technology, product and industry knowledge in the selection and use of FRG products can help you save time, money and lives.
Source: Doors and Hardware, 2012