I recently helped an architect design a wood-framed wall assembly with different membrane arrangements on each side of the wall. We used the calculated fire resistance approach from IBC 722 to achieve a one-hour rating for the wall. This project led me to create a new tool that calculates the fire resistance of the wall assembly based on the materials that you choose for each side. Check it out at the link below!
In the A/E world, there is much confusion regarding the definition of fire protection rating and fire resistance rating when designing doors, windows, transoms, sidelights and other openings in rated construction. These terms are often used interchangeably by mistake, but they represent two very different types of assemblies. A third term, "fire rating", is often used as well, making the distinction even more confusing. In this article, we'll review the differences between fire resistance ratings and fire protection ratings and show you how to determine the requirements for your specific situation. All code references are to the 2018 IBC.
Before distinguishing between fire-resistance-rated assemblies and fire-protection-rated assemblies, it's important to note that both of these are types of fire-rated assemblies. So if someone refers to a fire-rated glazing assembly, they could be potentially referring to either a fire-resistance-rated assembly or a fire-protection-rated assembly. The majority of the requirements for either type of assembly come from IBC Table 716.1(2).
Fire Resistance Rating
Fire-resistance-rated assemblies are those that have been tested to ASTM E119 or UL 263. This is the same test that is used for rated wall, floor and ceiling assemblies. Therefore, if you have a door, window, shutter or any other type of openings protective that is tested to ASTM E119 or UL 263, it is treated no differently than a rated wall or floor. There are no limitations to the area or location where you can provide such opening protectives.
Functionally, these tests measure an opening protective's ability to stop the transmission of smoke/flames AND to limit the transmission of radiant heat. In order to pass ASTM E119 or UL 263, assemblies must limit the temperature rise on the non-fire side of wall/floor to 250 degrees or less.
Any fire-rated glazing assembly, whether a fire-resistance-rated assembly or fire-protection-rated assembly, is required to be labelled per IBC 7188.8.131.52. The markings for these assemblies are shown in IBC Table 716.1(1) and replicated in the table provided below. For fire-resistance-rated glazing, you are looking for markings containing either a "W" or "F". If the marking does not contain either of these letters, the assembly is not fire-resistance-rated. Fire doors are required to be labelled per the requirements of NFPA 80.
Fire Protection Rating
Fire-protection-rated assemblies are those that have been tested to one of the following:
Functionally, these tests measure an opening protective's ability to stop the transmission of smoke/flames but do not test for the transmission of radiant heat. There are a number of limitations on the size and use of fire-protection-rated assemblies.
Fire-protection-rated openings have area limitations as indicated in the table below. Remember that these apply only to fire-protection-rated assemblies. Fire-resistance-rated opening protectives are treated no differently from the wall itself and are not limited in area.
In interior fire doors that require a 1-hour rating or greater, fire-protection-rated glazing is permitted in the door vision panel up to 100 square inches. The glazing in the door vision panel is required to pass the hose stream test and bear the "D" and "H" markings. The duration (in hours) of the required rating depends on the type and rating of the wall itself - specific requirements are provided in IBC Table 716.1(2). If a vision panel greater than 100 square inches in area is desired, the vision panel must be fire-resistance-rated glazing and bear the "W" marking. Additionally, vision panels exceeding this area in exit stairways, ramps and passageways must meet the maximum temperature rise criteria of 450 degrees after 30 minutes and bear the "T" marking. There is an exception for this temperature rise criteria if the building is fully-sprinkler protected in accordance with NFPA 13 or 13R. Finally, sidelights and transoms adjacent to fire doors that require a 1 hour rating or greater are required to have a fire-resistance-rating equal to that of the wall itself; fire-protection-rated glazing is not permitted in these.
If the fire door requires a 45 minute rating or less, fire-protection-rated glazing is permitted in the door vision panel up to the maximum size tested. There is no requirement for fire-resistance-rated glazing in such doors. Sidelights and transoms adjacent to these doors are required to have a fire protection rating of either 20 or 45 minutes depending on the location. Refer to IBC Table 716.1(2) for the specific requirements.
Fire doors in rated exterior walls have slightly different requirements. If the exterior wall has a rating greater than 2 hours, the fire door is required to have at least a 90-minute rating and a fire-protection-rated vision panel is permitted up to 100 square inches in area. Any sidelights and transoms are required to have a fire-resistance-rating the same as the wall itself.
Exterior walls rated 2 hours or less are permitted to have fire-protection-rated glazing in the door vision panel, sidelight and transom. The rating requirement for these elements is the same as the door itself.
Fire-protection-rated glazing is permitted in certain fire windows in interior wall assemblies, up to a maximum rating of 45 minutes. Fire windows in fire walls and fire barriers (excluding atrium separation, incidental use separations and occupancy separations) are required to have fire-resistance rated glazing. Refer to the table below, based on requirements form IBC Table 716.1(3). Note that walls allowing fire-protection-rated glazing can be provided with fire-resistance-rated glazing as indicated, but this is not required.
*except those noted in the next row
Fire-protection-rated glazing is permitted in all fire windows in exterior walls, as described in the table below. IBC Table 705.8 provides requirements for opening protectives in exterior walls, so be sure to refer there as well. Depending on the fire separation distance, you may be permitted to have unprotected openings in a rated exterior walls. Conversely, if the fire separation distance is less than 3 feet, you are not permitted to have any openings in the exterior wall, even if they have a fire protection rating. Fire-resistance-rated glazing is always permitted since it must meet the same test criteria as the wall itself.
There are two types of fire-rated openings protectives: fire-resistance-rated and fire-protection-rated assemblies. Fire-resistance-rated assemblies have to meet the same test criteria, ASTM E119 or UL 263, as a rated wall or floor assembly. Since the test is the same, there are no size or location limits for where you can provide fire-resistance-rated protectives. Fire-protection-rated assemblies are tested to lesser criteria and are limited in size and location. Full requirements for both types of assemblies are found in IBC Table 716.1(2).
If you have been involved in the design or installation of a fire alarm system, whether as an architect, engineer, or owner, you have probably asked the question, "Is a strobe required here?" Like all engineering questions, the answer depends on a number of factors. In this post, I will walk through the code path step-by-step to help you understand where fire alarm strobes are required.
Starting Point: Is a Fire Alarm System Required?
The starting point for determining strobes requirements is the applicable building code for your jurisdiction. If you are in the United States, this is most likely based on the International Building Code (IBC). For projects located elsewhere, this could be NFPA 5000. Buildings owned or operated by the government could also be subject to other requirements, such as the GSA PBS-P100 or UFC 3-600-01. You may also be in a jurisdiction that enforces NFPA 101, which also has requirements for fire alarm systems.
Assuming the applicable code is the IBC (all references here are to the 2018 IBC), your first step is to check Section 907.2 to determine if a fire alarm system is required for your building. This section requires a fire alarm system based on occupancy type and other building criteria, such as classification as a high-rise building. In some instances, 907.2 requires a manual fire alarm system (pull stations) and in others a smoke detection system. For the purposes of this article though, the main concern is whether any type of fire alarm system is required at all. That's because, according to IBC 907.2, if a fire alarm system is required by Sections 907.2.1 through 907.2.23, occupant notification is required.
Fire alarm equipment required outside of Section 907.2 such as duct smoke detectors or elevator emergency operations would not trigger a requirement for strobes.
Fire Alarm Requirements by Occupancy
Fire Alarm Requirements for Specific Situations
In addition to the occupancy requirements above, IBC 907 provides requirements for specific building situations.
Step Two: Are Strobes Required?
Once you have determined that a fire alarm system is required, you'll want to flip ahead a few pages to determine which rooms require strobes. The starting point is IBC 907.5.2.3:
Public Uses Areas and Common Use Areas
Strobes are required in public and common use areas, with the exception of employee work areas, which are permitted to be provided with spare circuit capacity to account for future addition of strobes if needed for hearing-impaired employees. Public use and common use are defined terms in the IBC:
Common Use: Interior or exterior circulation paths, rooms, spaces or elements that are not for public use and are made available for the shared use of two or more people.
Public Use Areas: Interior or exterior rooms or spaces that are made available to the general public.
Examples of spaces that fall under one of these categories are: lobbies, corridors, circulation areas, meeting rooms, conference rooms, assembly areas, public or shared restrooms, retail spaces, and classroom. This is by no means an exhaustive list, so you'll need to consider each space in your building to verify if it falls under the definition of public use or common use.
Groups I-1 and R-1
Strobes are required in a certain percentage of dwelling and sleeping units in Group I-1 and R-2 occupancies. Refer to the table below, replicated from IBC Table 907.5.2.3.2.
Group R-2 occupancies requiring a fire alarm system must have the capability to support strobes appliances in the future. The intent is that the fire alarm system has the capability to be modified if a hearing impaired occupant were to move into the sleeping or dwelling unit.
Step 3: Requirements Outside the IBC
The final step is to review other documents that could drive strobe requirements. One common question is whether or not ADA Accessibility Guidelines (ADAAG) or NFPA 72 require strobes in certain rooms. Neither of these documents actually require a fire alarm system or strobes to be installed at all. When a fire alarm system is provided, however, ADAAG brings in requirements for where visible notification is required. Similarly, NFPA is only applicable when the IBC or other applicable codes require a fire alarm system.
Assuming you are required to provide a fire alarm system, the requirements of NFPA 72 would apply (ADAAG would also apply, assuming your building is required to comply with the Americans with Disabilities Act (ADA), which is a longer discussion for another article). In most cases, if you provide a fire alarm system and a strobe layout that complies with the IBC and NFPA 72, you will meet the requirements of ADAAG.
The general process for determine strobe requirements is: