For such a simple product, the code requirements that apply to gasketing can be complex and confusing. Here is a simple breakdown with links to articles which provide more information:

Gasketing, sweeps, door bottoms, and thresholds installed as part of a fire door assembly must be listed for that purpose. The manufacturer’s catalog will identify which products are listed for use on a fire door assembly.

Not all fire doors or smoke doors require gasketing or thresholds, and the codes and standards don’t specifically state where these products are required. Typically, gasketing must be installed where the code or standard requires limited air infiltration when the assembly is tested to UL 1784 – Standard for Air Leakage Tests of Door Assemblies. A code reference to testing in accordance with UL 1784 is the key when trying to determine whether a door is required to have gasketing. The IBC and NFPA 101 have differing requirements on this, so there are two articles that cover each of these sets of requirements in detail (IBC, NFPA 101). Products which meet the air infiltration criteria will be listed for use on smoke doors, and the manufacturer’s catalog will designate which products have that listing.

For most gasketing and door bottoms used on fire door assemblies, the listing covers installation on fire doors that meet the clearance requirements of NFPA 80. When a door has clearances that are too large, installing most gasketing and door bottoms will not bring the door back into compliance. There are products that have been tested for use on fire doors with excessive clearance, but the listings include limitations on the door material, rating, and amount of clearance. Some of those products are linked in this blog post. If you have not read the article referenced in ShortCodes 3F – Fire Door Test Methods, it describes a fire test on doors with excessive clearance.

For pairs of doors, the meeting stiles may require gasketing if the air infiltration has to be limited when tested in accordance with UL 1784. Some fire door listings require overlapping astragals at the meeting stiles, but many manufacturers do not require astragals. When overlapping astragals are installed on a pair of fire doors, a coordinator is usually required in order to ensure that the doors close in the proper sequence. It’s also important to make sure that the overlapping astragal does not inhibit egress through the doors.

This Decoded article includes some FAQs about thresholds and gasketing for fire doors, and if you need a refresher on thresholds and gasketing, this optional video covers some of the basics:

After reviewing these materials, proceed to the review questions below.


Review Questions

1. A reference to which of the following in a code or standard indicates that smoke gasketing is probably required for compliance?

  1. NFPA 80
  2. NFPA 105
  3. UL 10C
  4. UL 1784

2. When clearances on a fire door are larger than what is allowed by NFPA 80, what is the most appropriate solution?

  1. Install gasketing that is listed for use on a fire door assembly
  2. Install gasketing that limits air flow when tested in accordance with UL 1784
  3. Install gasketing that has been listed for use on doors with excessive clearance
  4. None of the above – the door must be replaced

3. On a pair of outswinging fire doors equipped with vertical rod fire exit hardware, what is the proper method of limiting air infiltration at the meeting stiles?

  1. Listed meeting stile gasketing
  2. Listed overlapping astragal
  3. Rabbeted edges
  4. All of the above are acceptable

Answers: 1 – D, 2 – C, 3 – A