Lower Bottom Rods

Q: I am a consultant and I am surveying a system where the bottom strike rod and the floor receiver have been removed.  I think this “field” modification may void the UL rating.  Is there a reference for clarification on this?

A: You’re not going to find a section in any NFPA code or standard that says “There must be a lower bottom rod on fire rated doors”. But, nonetheless, they are required when the manufacturer says they are required. The manufacturer of fire rated door assemblies have to have them listed by on independent testing laboratory, such as UL or ETL (Intertek). The manufacturer submits their fire door assembly for testing and if it passes the test, then the testing laboratory will list it as meeting the required standards based on the total assembly, including the hardware.

For decades certain types of cross-corridor fire rated door assemblies were designed with surface mounted hardware that included the lower bottom rod for latching. And for decades, hospital employees hit that lower bottom rod with carts and instead of repairing the rod, the poorly-informed maintenance staff would just remove the rod. Along comes better-informed surveyors who identifies that this is not correct and cites the hospitals.

Recently, some door manufacturers are actually designing cross-corridor fire-rated doors with surface hardware that eliminates the lower bottom rod all-together. This design was tested and listed by the testing laboratories. Some of these designs have employed devices what are commonly called ‘fire-pins’ in the lower part of the door that releases a pin from one door leaf to the other door leaf to ‘lock’ it in place when the ambient temperature at the floor approached 500 degrees (or so).

As you come across fire-rated doors that have surface mounted hardware but no lower bottom rods, I suggest you do the following:

  • Check the horizontal crash bar hardware and confirm if there is an opening on the underside of housing for a lower bottom rod. If not, then check the independent testing laboratory label on the horizontal crash bar assembly to confirm that it is listed for use as fire-rated hardware.
  • If there is an opening on the underside of the housing, then check to see if there is a fire-pin installed on one of the door leafs.
  • If there is no fire-pin installed, then ask the organization to provide you with documentation that the door assembly as presented meets the requirements for the UL (or ETL) listing. If they can provide that information, then review it and determine that the remaining hardware is installed as designed.
  • If they cannot provide that information, then cite them for non-compliant modifications to a fire-rated doors assembly.