The following are excerpts taken from NFPA 80 which concerns the use and application of hardware for fire doors. These should always be followed when specifying hardware for doors that must be fire rated. There are exceptions to these rules when allowed by the local authorities having jurisdiction so please consult local codes as well.
The clearance under the bottom of the door shall be as follows:
- The clearance between the bottom of the door and a raised noncombustable sill shall not exceed 3/8 in. (9.53 mm).
- Where there is no sill, the clearance between the bottom of the door and the floor shall not exceed ¾ in. (19.1 mm).
- (c) The clearance between the bottom of the door and the rigid floor tile shall not exceed 5/8 in (15.9 mm).
Doors swinging in pairs and having a fire protection rating of more than 1 ½ hours shall have an overlapping astragal.
Doors swinging in pairs, where located within a means of egress, shall not be equipped with astragals that inhibit the free use of either leaf. The free use shall mean that the forces required to fully open any door manually in a means of egress shall not exceed 15 lbf (67 N) to release the latch, a 30 lbf (133 N) to set the door in motion, and a 15 lbf (67 N) to open the door to the minimum required width. These forces shall be applied at the latch stile to the minimum required width.
Pairs of doors that require astragals shall have at least one attached in place so as to protect approximately 3/4 in. (19.1mm) or as may be otherwise indicated in the individual published listings.
Hinges shall be as required in Table 2-8(a).
Locks or Latches
Only labeled locks and latches or labeled fire exit hardware (panic devices) meeting both life safety requirements and fire protection requirements shall be use.
All single doors and active leaves of pairs of doors shall be provided with an active latch bolt (one that cannot be held in a retracted position), as specified in Table 2-8(b).
Exception No. 1:
Doors other than those used in means of egress shall be permitted to be provided with dead bolts in addition to the active latch bolts or as otherwise permitted by the authority having jurisdiction.
Exception No. 2:
Locks with dead bolts that are interconnected with latch bolts and retract when the latch bolt is retracted shall be permitted for use on fire doors within a means of egress.
Exception No. 3:
Latching arrangements that do not provide positive latching in the normal mode shall be permitted to be used provide that, in a fire emergency, the door becomes positively latched by means of an automatic fail-safe device that is activated by an automatic fire detector (approved by the local authority having jurisdiction).
Where both leaves are required for exit purposes, they shall be provide with labeled fire exit hardware.
Where permitted by authority having jurisdiction, pairs of doors not provided with an astragal are permitted to have labeled fire exit hardware and an open back strike installed on the inactive leaf, and either labeled fire exit hardware or any labeled latch capable of being opened by one obvious operation from the egress side on the active leaf.
Where a pair of doors is needed for the movement of equipment and where the inactive leaf of the pair of doors is not required for exit purposes, labeled top and bottom self-latching or automatic flush bolt or labeled two point latches are permitted.
Manually operated, labeled top and bottom flush or surface bolts on the inactive leaf of a pair of doors shall be permitted to be used where acceptable to the authority having jurisdiction, provided they do not pose a hazard to safety of life. This provision limits their use to rooms not normally occupied by humans (e.g. transformer vaults, storage rooms). The inactive leaf shall not require a closer.
The throw of single point latchbolts shall not be less than the minimum shown on the fire door label. If the minimum throw is not shown or the door does not bear a label, the minimum throw shall be as required in Table 2-8(b).
The top of the plate shall be a maximum of 16 in. (406 mm) above the bottom of the door. Such plates shall be permitted on both door faces. No other plates shall be installed.
Where there is an astragal or projecting latch bolt that prevents the inactive door from closing and latching before the active door closes and latches, a coordinating device shall be used. A coordinating device shall not be required where each door closes and latches independently of the other.
A closing device shall be installed on every fire door.
Where pairs of doors are provided for mechanical equipment rooms to permit movement of equipment, the closing device shall be permitted to be omitted on the inactive leaf.
Operation of Doors
All swinging doors shall be closed and latched at the time of fire. For the purposes of this section the operation of doors is divided into three catagories.
The door shall swing easily and freely and shall be equipped with a closing device to cause the door to close and latch each time it is opened. The closing mechanism shall not have a hold open feature.
Automatic Closing Doors
A door shall be permitted to be made automatic closing by the installation of a closing device and a separate, labeled, fail-safe door holder/release device or a hold-open mechanism that shall be permitted to be an integral part of the basic closing device or an integral closing device that permits free swinging of the door during normal operation and automatically closes the door during an alarm condition, provided the hold-open mechanisms are released by one or a combination of automatic fire detectors acceptable to the authority having jurisdiction.
Power Operated Fire Doors
Power operated fire doors shall be equipped with a releasing device that shall automatically disconnect the power operator at the time of fire, allowing a self-closing or automatic device to close the door irrespective of power failure or manual operation.