February 1, 1996
96-006
The Office of the Fire Marshal (OFM) has received several inquiries regarding the compliance of tubular core doors with Retrofit requirements for suite and corridor fire separations. These tubular core doors appear to satisfy the existing door criteria by having a minimum thickness of 45mm and a total weight that is approximately equal to a solid wood door. However, an examination of the cross section reveals that the core material of tubular core doors consists of wood particle board with parallel cylindrical voids running in either a vertical or horizontal direction. As this type of door is of substantial construction but not completely solid, the intent of the existing door provisions under Sections 9.5 and 9.6 of the Ontario Fire Code as it applies to these doors seems unclear.
Sentences 9.5.2.8.(4) and 9.6.2.6.(5) of the Fire Code state that existing closures consisting of 45mm solid core wood doors installed in solid wood or hollow metal frames and equipped with self-closing devices are acceptable where a 20-min rated closure is normally required. Although these doors may not perform to the same level as a 20-min rated door, they are capable of resisting the spread of smoke and fire long enough for occupants to evacuate the floor. The provision to allow existing doors of substantial construction (i.e., doors that approximate the fire performance of a rated wood door) was included in the Fire Code as minimal benefit would be gained in upgrading to rated closures.
The lack of exact specifications for a solid core wood door in the Fire Code has created some uncertainty in accepting doors that contain hollow voids. A number of different door types have been identified which satisfy the minimum thickness criteria of 45mm. These doors appear solid but in fact, they contain hollow voids. One example is the tubular core door which is included in the Underwriters Laboratories of Canada (ULC) standard, ULC S113, The Standard Specification for Wood Core Doors Meeting the Performance Required by CAN4-S104 for 20-min Rated Closure Assemblies. Since these doors may not be labelled, it may be difficult to determine compliance with this standard without destructive examination.
Although the structural integrity of tubular core construction under fire exposure may be sufficient, discussions with ULC and observations at fire scenes indicate that tubular core doors tend to warp excessively under extreme fire conditions. This raised concerns that these doors may not perform adequately in resisting the spread of smoke and fire due to excessive deflection. In response to these concerns, the OFM initiated a test in conjunction with ULC to compare the fire performance of a tubular core door with a completely solid wood core door.
The only objective of the test was to compare the performance levels of the doors under identical fire conditions. The test standard chosen was, CAN4-S104-M-80, Standard Method for Fire Tests of Door Assemblies. To ensure a uniform fire exposure, both doors were tested simultaneously on the same test panel assembly at ULC laboratories. The furnace was fired in accordance with the time-temperature curve in the standard. This is considered more severe than the typical fire exposure received by an entrance door to a suite of fire origin. At the conclusion of the 20-min. fire test, both doors remained in place even when subjected to a hose stream. Although the tubular core door exhibited some deflection at the top edge, it was still capable of providing an acceptable degree of protection to the door opening.
The test results confirm that doors of tubular core construction provide an acceptable level of protection for openings between suites and a public corridor and thus are capable of achieving the necessary fire performance envisioned by the current Fire Code requirement. However, there is need to clarify what is meant by the term 'solid core' as per the Fire Code. Solid core wood construction includes doors of completely solid cores (see diagram 1) and any wood core configuration where the core material is in direct contact with the entire surface of both door face panels (see diagram 2). There should be no part of the door cross-section consisting only of the two combustible door face panels with no wood core material between.
In conclusion, it is the OFM's opinion that existing tubular core doors may be accepted under the provisions of Sentences 9.5.2.8.(4) and 9.6.2.6.(5) of the Fire Code as solid core wood construction. Furthermore, destructive examination of any "solid core" wood door to confirm compliance with a standard is not required by the Fire Code.
For additional information or inquiries, contact your Regional Office of the Fire Marshal.
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