Printed from the blog of Lori Greene, AHC/CDC, CCPR, FDAI
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Jun 06 2017

QQ/WWYD? Excessive Clearance on Fire Doors

The rapidly-approaching deadline for fire door inspections in health care facilities is resulting in LOTS of questions about fire door assemblies.  The most FAQ in the last few weeks has been…

When a fire door has more clearance than what is allowed by NFPA 80, can a door sweep and/or gasketing be added to solve the problem? 

Excessive clearance is one of the most common problems found with existing fire door assemblies.  NFPA 80 – Standard for Fire Doors and Other Opening Protectives limits perimeter and meeting stile clearance to a maximum of 1/8 inch for wood doors and 1/8 inch +/- 1/16 inch for steel doors, when measured on the pull-side face of the door.*  For most fire doors, clearance at the bottom of the door is limited to 3/4 inch.

There are many types of gasketing, thresholds, door bottoms, and sweeps that are listed for use on a fire door.  However, almost all of these products are designed and tested for use on doors which have clearances within the acceptable limits shown in NFPA 80.  Installing this gasketing on a non-compliant fire door assembly will not bring the opening back into compliance.

Crown Fire Door Products invited me to attend a test at UL a few years ago, and I wrote about it for Doors & Hardware magazine. Click on the photo of Uriah Noble installing Crown’s door extender to read the article. Photos courtesy of Leslie Miller, Fire Protection Publications

Several products have been introduced in the last few years that are tested and listed for use on fire doors with clearance that exceeds what is allowed by NFPA 80.  When using these products, it’s very important to consider the limitations of the product – for example, the maximum clearance that the product has been tested to accommodate, the door/frame material, and the rating.

The 2016 edition of NFPA 80 has been updated to include references to this type of product, allowing their use for doors with clearance in excess of what is allowed by the standard when the products are installed in accordance with their listings.  Prior to the 2016 edition, NFPA 80 does not mention any methods of resolving oversized-clearance problems, but the standard does address alternative methods and equivalency, which would allow AHJ approval of listed products even if they are not specifically addressed in NFPA 80.

One thing to keep in mind, which is mentioned in the 2016 edition of NFPA 80 and in the NFPA 80 Handbook, is projection of the latchbolt.  If the clearance is too large, latchbolts at the bottom of the door or on the latch edge may not engage the strike securely enough.  To determine the minimum engagement, refer to the manufacturer’s listings – according to the NFPA Handbook, most latches are required to engage the strike by 11/16 inch.  If gasketing and/or door bottoms are added to an existing door, the assembly must be tested to ensure that the door will still close and latch properly.  Shimming the hinges with steel shims may help to decrease the latch-side clearance.

Listed below are the products that I have seen, that can be used when fire doors have excess clearance.  If you know of other products, please leave them in the reply box and I will add them.

* The 2016 edition of NFPA 80 also allows the extra tolerance of +/- 1/16 inch for high-pressure decorative laminate (HPDL)-faced doors, flush wood doors, and stile and rail wood doors installed in hollow metal frames – when the assembly is rated for 20 minutes.  Assemblies of these types that are rated for more than 20 minutes are limited to 1/8-inch clearance between the door and frame, and at the meeting stiles of pairs.  Doors constructed of other materials (not including hollow metal doors) are limited to 1/8-inch clearance unless permitted by the door, frame, and latching hardware listings. 


If you’d like me to send you some of our laminated cards showing the requirements for fire door inspection, email me or leave your address and the desired quantity in the reply box.  The cards are shown on the fire door page of iDigHardware.

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6 Responses to “QQ/WWYD? Excessive Clearance on Fire Doors”

  1. Cda says:

    Thank you for the info

  2. Don Hicks says:


    Would you please send 50 of the laminated cards to me?

    Don Hicks
    Overhead Door Company Of Atlanta
    221 Armour Drive NE
    Atlanta GA 30324

  3. Robby Castro says:

    Great information, thank you. What is this NFPA handbook, and where can I get a copy? Is it distributed by the NFPA, or an outside source? My concern is the 11/16″ engagement. I’ve researched this everywhere and have yet to find a code that lists how far a latch needs to engage, or penetrate. I’ve seen “minimum throw”, but never engagement. Any help you can offer would be much appreciated. Thanks again.

  4. BK Kersenbrock says:

    Hi Lori

    I would like to further explore Mr. Castro’s inquiry as you didn’t specifically address the 11/16″ flush bolt/ strike engagement. Years ago, while attending DHI’s FDAI (600) course, the text book stated that the flushbolt should engage the floor strike one half inch (minimum). At the time, we could not find anywhere in the listings or manufacture’s instructions, stating this required adjustment. I even asked Mr. Pardo. He said that the half-inch engagement is based on a mathematical formula where the margin between the bottom of the door (flush bolt head) and top of floor strike is 1/4″. This is based on 3/4″ flush bolt throw. [After factoring a 1/8″ margin between the meeting stiles.]
    We have (again) looked at the UL listings, as well as manufacturer’s installation instructions for several well respected brands, including Ives and DCI. To date, we have not found any dimensions for either projection or strike engagement listed.
    Can you direct us further or provide clarification? Thank you.

    • Lori says:

      I have looked for this too, and have not found where it states the specific amount of engagement required. Hopefully someone else will know where to find it.

      – Lori

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