The question has to do with opening force for fire doors – particularly stairwell doors. Trying to find the balance between pressurized stairwells and the maximum allowable opening force for the stairwell doors has been an ongoing problem. I wrote about it back in 2014, and I still don’t have a good answer.
The maximum opening force for doors allowed by the accessibility standards is 5 pounds, but fire doors and exterior doors are exempt from this requirement in the ADA standards and ICC A117.1. NFPA 80 does not limit the opening force for fire doors, but in Annex A of the standard there is a section reinforcing the importance of sufficient closing force to allow the fire door to latch. This section recommends a door closer with a spring size of 3 or 4, which will require well over 5 pounds of opening force.
The model codes establish an opening force limit of 30 pounds to set a fire door (or exterior door) in motion, and 15 pounds to open the door to the fully-open position; some state and local codes further restrict these forces. Even with the 30lb/15lb allowable forces, there are often problems getting doors swinging into pressurized stairwells to comply. When the air pressure is factored in, the doors often exceed the allowable forces to open.
This prompted a question from a reader:
Where did the limit of 30 pounds to set the door in motion and 15 pounds to open the door fully come from?
This is a really good question. These limits are far beyond the 5-pound limit for accessibility, so these doors would be problematic for some people with disabilities to operate. Were these numbers just randomly selected, or was research done regarding forces that would allow the doors to be operable by the majority of building occupants? I understand the reason for the exclusion of fire doors and exterior doors from the 5-pound limit, but it’s interesting that the codes and standards don’t include a means of providing more closing force while also allowing people with disabilities to use the doors. And with regard to pressurized stairwells, how far into the closing cycle is the 30-pound force allowed? Or if 15 pounds to open the door to the fully-open position is acceptable, why not 16 pounds? Or 20?
I did some research and found that these limits were added to the NFPA codes in the 1985 edition. I don’t have the code change proposal and reason statement from that code development cycle – maybe that would give us a clue about where the limits came from.
The IBC Commentary doesn’t really help:
The ability of all potential users to be physically capable of opening an egress door is a function of the forces required to open the door. The 5-pound (22 N) maximum force for pushing and pulling interior swinging doors without closers that are part of the means of egress inside a building is based on that which has been deemed appropriate for people with a physical limitation due to size, age or disability. The operating force is permitted to be higher for all exterior doors, interior swinging doors that are not part of the means of egress, doors that are part of the means of egress but also serve as opening protectives in fire-resistance-rated walls (i.e., fire doors), sliding doors and folding doors. This recognizes that doors with closers, particularly fire doors, require greater operating forces in order to close fully in an emergency where combustion gases may be exerting pressure on the door assembly. Similarly, exterior doors are exempted because air pressure differentials and strong winds may prevent doors from fully closing automatically. Requirements for power-operated doors are in Section 1010.1.4.2. The opening force is different than the force to retract bolts or operate other types of door hardware.
A maximum force of 15 pounds (67 N) is required for operating the latching mechanism. Once unlatched, a maximum force of 30 pounds (133 N) is applied to the latch side of the leaf to start the door in motion by overcoming its stationary inertia. Once in motion, it must not take more than 15 pounds (67 N) of force to keep the door in motion until it reaches its full open position and the required clear width is available. To conform to this requirement on a continual basis, door closers must be adjusted periodically and door fits must also be checked and adjusted where necessary.