Issue 25: Changes to the International Building Code
By David Bowman, P.E., and Beth Tubbs, P.E.
The two code change cycles that occurred between the 2006 Editions of the International Codes and the 2009 Editions brought a greater amount of life safety provisions for high-rise buildings, more provisions for emergency responder safety, and more life safety protection for single family residences and townhouses. This article will briefly touch upon those changes.
The high-rise building provisions in the 2009 International Building Code will require an additional exit stair for buildings greater than 420 feet (128 meters) in height, and a fire service access elevator for high-rise buildings greater than 120 feet (30 meters) in height. In addition, all high-rise buildings will be required to have luminous exit path markings and, in very tall buildings (greater than 420 feet - 128 meters) the required bond strength for spray applied fire resistance material will be more than doubled, from 430 psf (20 kPa) to 1000 psf (48 kPa).
Another big change is the specific allowance of elevators for egress under certain conditions.
403.5.4 Additional exit stairway. For buildings other than Group R-2 that are more than 420 feet (128 meters) in building height, one additional exit stairway meeting the requirements of Sections 1009 and 1022 shall be provided in addition to the minimum number of exits required by Section 1021.1. The total width of any combination of remaining exit stairways with one exit stairway removed shall not be less than the total width required by Section 1005.1. Scissor stairs shall not be considered the additional exit stairway required by this section.
Exception: An additional exit stairway shall not be required to be installed in buildings having elevators used for occupant self-evacuation in accordance with Section 3008.
The provision for an additional exit stairway in very tall buildings was included in the 2007 Supplement. The proponents, the International Code Council Ad Hoc Committee on Terrorism Resistant Buildings, cited the work of the National Institute of Standards and Technology (NIST) as reflected in its World Trade Center Report.1 This is an additional stair to that already required by Chapter 10 of the IBC. If a building is required by Chapter 10 to have 3 stairs, it would require a fourth stair.
There is an important exception to this requirement which will allow the use of elevators for egress in place of the additional stair. This allowance comes with a set of requirements in Chapter 30 for such elevators. The use of such elevators does not allow the reduction in the egress width required in Chapter 10. The package of requirements also includes features such as a minimum elevator lobby size and level of construction, water protection from sprinkler activation and a two-way communication system.
The additional stair requirement is intended to address the concern of what is often termed counterflow. Counterflow occurs when fire fighting and rescue activities interfere with egress by reducing the required egress width. The concept of counterflow is primarily a concern when a building needs to be fully evacuated. The extended period of time that may be needed to fully evacuate a very tall building will likely mean that people will still be evacuating while firefighting operations are taking place. It implements, in part, Recommendation 17 of the National Institute of Standards and Technology (NIST) World Trade Center (WTC) report.
Historically, high-rise buildings have been designed with the assumption that evacuation would be phased and generally be localized to several floors affected by the incident. Until the 2009 code, the IBC had been written to reflect this practice and did not necessarily anticipate full building evacuation. The NIST WTC report specifically recommended that the building and fire codes consider full building evacuation.
This additional stair is not proposed to be a dedicated fire department stair. The intent of the proposed provision is that the fire department be able to choose the stair which is most appropriate for the actual fire event. The principal purpose of this change is to maintain egress capacity in the case of fire events, but the additional stair will also shorten the time needed for full evacuation in non-fire events.
Requirements for egress path marking with photoluminescent material were also included in the 2007 Supplement and apply to all high-rise buildings. The proponent of this change was also the International Code Council Ad Hoc Committee on Terrorism Resistant Buildings.
The new section on exit path markings will require that photoluminescent exit path markings be provided in vertical exit enclosures in high-rise buildings. The 2006 IBC has no requirements for the installation of these markings. This proposal is intended to facilitate rapid egress and assist in full building evacuation and is drawn from Recommendations 17 and 18 of the National Institute of Standards and Technology's (NIST) report on the World Trade Center tragedy.
In the City of New York, after the first bombing of the WTC, requirements were instituted to require exit path markings in vertical exit enclosures. This proposal is taken directly from those requirements. (See issue #8 of Emerging Trends.)
Requirements for increased bond strength of spray-applied fire resistant material (SFRM) were also based on the findings of the NIST WTC study. The NIST investigation into the World Trade Center (WTC) tragedy documented that the proximate cause of the actual collapse was the action of a building contents fire on light steel members in the absence of spray applied fire resistant material, which had been dislodged. Events far less dramatic than an airplane attack may dislodge SFRM. The initiating events can be as simple as elevator movement, building sway or maintenance activities.
Recommendation 6 of the NIST WTC Report called for improvement of the in-place performance of SFRM.
There were several fire service safety features added to the I-Codes. One of the more significant changes was the addition of fire service access elevators in high-rise buildings over 120 feet (30 meters) in building height in the IBC. This set of requirements enhances the current features for fire fighters provided by elevators already. The enhanced features focus upon a dedicated and more highly protected lobby, direct access to a stairway, location of standpipes within the associated exit stairway, elevator monitoring, protection of wiring and cables associated with the elevator and standby power for several key features associated with the elevator, such as machine room ventilation and cooling.
The enhanced features focus upon the following:
- a dedicated and more highly protected lobby
- direct access to a stairway
- location of standpipes within the associated exit stairway
- elevator monitoring
- protection of wiring and cables associated with the elevator and standby power for several key features associated with the elevator, such as machine room ventilation and cooling.
Another important change related to fire fighter safety addressed in the International Fire Code is the requirement for radio coverage in all new buildings. This allows fire fighters to continue to use communication systems that they are already familiar with and use everyday when entering any building. A two-way communication system installed within the building is still allowed as an alternative but must be approved. The IBC references this new requirement for buildings such as high-rise buildings covered in Chapter 4 of that book.
The 2009 International Residential Code will contain requirements for additional safety features, including residential fire sprinkler systems as well as carbon monoxide detectors.
David Bowman and Beth Tubbs are with the International Code Council.
References
1. Final Report of the National Construction Safety Team on the Collapses of the World Trade Center Towers. NIST NCSTAR 1. National Institute of Standards and Technology, 2005.
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