Refresher-Forcible Egress and Entry
InDetail: Forcible entry through building security window systems
Building with Serious Fire Safety Deficiencies
As more buildings become retrofitted with high security windows, an increased need has arisen for firefighters to become more knowledgeable on how the window products work.
BY MICHAEL NG
OFM FIRE PROTECTION ENGINEER
Recent terrorist attacks involving explosives on high profile buildings around the world continue to raise security concerns with building owners. These events have prompted owners to improve security around their building perimeter in an effort to better protect their occupants. Since a building’s most vulnerable component is its exterior glazing, upgrading this material to resist penetration from an attack has been identified as one method of ‘hardening’ it. As a result, more and more buildings are now being retrofitted with security window system products.
High velocity flying glass fragments generated as a result of window impact and breakage is a major contributor to occupant injuries. Currently, there are various window systems that offer protection against this type of hazard. One system consists of a sheet of plastic film applied to the interior side of a window. Another design is laminated glass, which consist of multiple panes of glass bonded together with an interlayer of thermoplastic. Ballistic resistant windows, which are designed to resist an attack by firearms, consist of proprietary combinations of glass, laminates and polycarbonate to obtain the required rating from a testing agency. Some window systems may also have secondary catcher systems such as blast curtain/blast shields to limit the amount of glass that enters the facility should the exterior glazing fail.
Security window systems come in varying grades to suit the level of glass protection required. Besides providing resistance against explosion and ballistic attacks in commercial buildings, other applications include protection against hurricane winds, earthquakes, and burglary/vandalism incidents in homes. Grades can be varied based on film and laminate thickness and the method in which they are applied to the glazing. Film that is mechanically secured to the window frame is more resistant than film secured only onto the glass portion of the window. Also, the deeper the window bite, which is the depth of glass captured within the frame, the more resistant it is.
The security features of these products pose additional challenges for unsuspecting fire and emergency responders who need to gain forcible entry or egress through an inoperable window for rescue or firefighting operations. Since these products are transparent and unlabelled, firefighters will not be aware of the presence of an upgraded window system until they attempt to break it without success. Without the appropriate tools and training, these windows can severely hinder firefighter entry and egress, jeopardizing the safety of personnel and building occupants.
To address these concerns, the U.S. General Services Administration (GSA) and Department of Homeland Security (DHS) commissioned a study in 2003 to perform forcible entry testing of various air blast glazing system configurations. These configurations included:
Security film applied to window interior.
Security film applied to window interior and mechanically attached to framing.
Single-paned laminate glass with varying thickness of lamination.
Insulated glass units with laminated inner pane.
Ballistic resistant window.
Blast curtain affixed behind window.
Untreated annealed glass (for reference purposes).
The study involved observing professional firefighting personnel utilizing standard operating procedures with various forcible entry tools to gain entry and egress through an array of window system mock-ups. The purpose was to gain knowledge on what are the most effective techniques and appropriate tools for firefighters for penetrating these window systems. The following is a summary of key findings generated by the study with respect to the proper use of tools and techniques:
With the exception of ballistic resistant windows, firefighters were able to gain entry into all window system mock-ups using conventional firefighting hand tools such as pickhead/flathead axes, sledge hammer, haligan tool and pike poles. Window clearing times ranged from 10 seconds to three minutes depending on the tool used and window configuration. Power tools such as circular saws and chain saws with carbide tipped blades and chains were the most effective for the stronger non-ballistic resistant systems.
A power circular saw with carbide-tipped blade was the most effective tool for penetrating ballistic resistant windows. Window clearing times took a minimum of two minutes. Conventional firefighting hand tools were found to be ineffective against these windows. When using power tools, firefighters should wear their SCBA for protection against glass dust.
For window systems that permit the use of hand tools, an effective technique was to use an 8 lb (3.6 kilogram) pickhead axe to cut/chop along the top, clear halfway down the two sides, then the bottom, followed by the remainder of the two sides.
The most effective entry technique using power tools was to cut across the top of the window, followed by one of the sides, then the bottom and finally the remaining side. see attachments
Where a blast curtain is encountered after clearing the outer glazing, a serrated pocketknife was effective for cutting the curtain horizontally along a seam.
An effective technique utilized for emergency egress was to cut two sides of a triangle or three sides of a rectangle with hand tools and use the remaining uncut side as a flap for opening up the glazing. Emergency egress took less time than forcible entry due to the shorter length and fewer number of cuts required to permit escape.
As a result of these findings, fire departments may want to update their standard operating procedures to reflect the growing use of security window systems and their implications. Some measures to consider include:
Work with owners to identify buildings that have been retrofitted with security window systems and update the Fire Safety Plan accordingly.
Provide hands on training to staff on forcible entry through security window systems.
Ensure that all responding personnel carry the appropriate power tools with the proper chains and blades.
Ensure that adequate personnel are onsite when responding to a call to a building that knowingly contains security window systems.
If a firefighter is unable to escape through a window, he/she should radio in to relay his/her location and try to find another location to exit.
More information on this subject matter, including training material, report, and demonstration videos and can be found at the General Services Administration-Office of the Chief Architect website at www.oca.gsa.gov/firefighter/introduction.php.