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Aug 30 2016

WWYD? Clearance vs. Undercut

Category: Fire Doors,WWYD?Lori @ 12:18 pm Comments (20)

Last week I got a call about a problem that led me to do some research on the difference between the clearance and the undercut on a fire door.  On the project in question, the fire doors were supplied with a 5/8-inch undercut, which would typically result in a clearance dimension under the door that meets the requirements of NFPA 80.  But when the frames were installed, the slab was not consistent so the bottom of the frame was not set level with the slab – the frames were set higher.  When the flooring was installed and the doors were hung, the clearance between the bottom of the door and the top of the flooring was larger than the 3/4-inch maximum allowed by NFPA 80.

The contractor considers the door and frame supplier responsible for the problem – even though the supplier did not install the frames.  The project is a health care facility, and the owner is requiring the newly-installed fire doors to be code-compliant, and rightly so.  The supplier maintains that they provided doors with a code-compliant undercut, and can not be held responsible for the non-code-compliant clearance, since the floors are out of level and the installer did not place the bottom of the frames at floor level.  So whose problem is it?

I went looking for some documentation to help clarify the difference between clearance and undercut.

The SDI Fact File includes these definitions:

UNDERCUT: The distance between the bottom of door and the bottom of the frame.

FLOOR CLEARANCE:  The distance between the bottom of the door and the top of the material directly below the door. This varies with applications, such as concrete, any floor covering and/or a threshold.

The same SDI PDF includes information about setting the frame with the bottom of the frame at floor level.  It’s in SDI 122 – page 23, which is page 90 of the PDF.

NAAMM/HMMA has a document called Defining Undercuts, which includes similar information and this figure indicating the undercut and the clearance:

Clearance vs Undercut

Although NFPA 80 doesn’t clearly state the difference between the undercut and the clearance, the NFPA 80 Handbook includes a paragraph stating:

“Undercutting is not to be used interchangeably with door clearance. Many users of the document often confuse the two terms and concepts, assuming that undercut and clearance under a fire door are the same item. Chapter 4 mandates that the maximum clearance under a fire door be not more than ¾ in. (19 mm). Undercutting is the process required to achieve this ¾ in. (19 mm) door clearance. Undercutting is permitted in some job site preparation for wood and composite doors per”

It seems clear to me that if fire doors are supplied with the proper undercut and the frames are not installed by the door and frame supplier, the supplier should not be held responsible for clearances that are not code-compliant if the frames are not set at floor level or because the floor level varies excessively from one side of the opening to the other.  (Note: This is my opinion.)

Have you ever run into this situation?  Is there a way for suppliers to clarify where their responsibility ends?  What’s the best process for coordinating the door undercut with the various types of flooring that are used?  WWYD?

Graphic: National Association of Architectural Metal Manufacturers

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20 Responses to “WWYD? Clearance vs. Undercut”

  1. MartinB (aka lauxmyth) says:

    Seen similar in past. If the situation is as you describe, I see the responsibility with the contract installer. Like you, my opinion.

    I also believe there is a need for a new type of rated door hardware. After all, the 3/4 inch of clearance is there to limit airflow. If a door bottom cap are designed to screw/bolt to the door and fill the gap, it would do the same. Of course, this needs testing. May not be visually great but the choice is complete teardown of the frames. In some locations, the looks would not be a big issue.

  2. Jerry Richmond, AHC/CDC says:

    We made our own in-house drawing decades ago, similar to your NAAMM/HMMA drawing, clearly indicating the differences between the door “undercut” and the floor material “clearance”. It is included in all of our shop drawing submittals.
    As for responsibility, in this case, it is my opinion that this rests solely on the contractor.

  3. Rich says:

    If the supplier provided doors and frame that would be compliant if properly installed on a flat level floor, but are not compliant due to the installation on a non level floor, then the installer and contractor are at fault. The cheapest fix will probably to replace the doors on the installed frame with ones having a smaller undercut. Not the suppliers fault at all but they could be kind (and business wise) by offering some partial compensation if the doors are returned to them in resalable condition.

  4. Jason Freitas says:

    I am not sure if there is any more the supplier can do. I don’t believe they have any responsibility, in my experience. Unless the doors were not manufactured to the specs given to them by the contractor, that is completely the fault of the installers. I would maybe even put some blame on framers for not pointing that out. That is why you field check your roughs before ordering material.

  5. Bill Cushman says:

    This is where A good submittal comes in handy. At the front side of our submittal we have an entire section dedicated to the proper installation of frames as they pertain to the finish floor. Once bitten twice shy. Now, if one of our frames is installed wrong by a 3rd party, we can point to our installation instructions which are stamped and approved. CYA is the name of the game in this biz.

  6. Eric says:

    I agree with your opinion although I cannot find much in the way of standards that address this issue. Nothing in ANSI A250.11 but SDI-122 2015 mentions it. Page 23 states that the frame should be installed “on the floor, not ‘in’ the floor”. I’ve had the latter occur on a project where a self-leveling concrete was poured after the frames were installed which raised the floor up 5/8″. The GC called and told me the hollow metal doors were manufactured too tall for the opening and they were rubbing on the new floor. “I’m gonna back charge you for fixing this floor!” yadda, yadda, yadda. You know the drill. Once I politely showed Mr. Superintendent the real problem and helped him revise his story, he paid me to have them cut down.

  7. Raymond Holman, AHC says:

    Unless the architectural plans showed a slope in the floor, I’d say the supplier is off the hook. Another gotcha would be if the supplier did a jobsite walk as part of the bid process (assuming the floor was already there). If the installer was a sub and not a GC employee, my guess is that he’s being told it’s all his fault, too. The installer should have set the frame on the floor at the high point and shimmed the other leg. Should have informed the GC Superintendent at that point, too. Sounds like he may have set it even higher than needed. Coordination between trades is a GC responsibility and the installer should be aware of rules governing fire rated openings. Threshold? Ramp? As a material supplier, we depend on communication from the jobsite. I’m sure someone will find fault with this logic.

  8. Jason says:

    Sounds like it’s the contractor’s problem for either not making the floor level, or not taking that into account when ordering or installing the doors. The door supplier only makes what they are told, and made doors that would work in a normal installation.

  9. Chuck Park says:

    In this particular scenario, I would put the blame squarely on the installer and whomever spec’ed-out the doors and frames.
    The supplier did what was required, which was to supply the items specified for the job, and has no culpability in this.

  10. Jared says:

    An electrical supply house is not responsible for a 120 lighting ballast that blew because the installer ran 220 to it. Even Von Duprin says they won’t warranty their El devices if the proper gauge wire isn’t used. If a supplier provides doors and frames per spec it SHOULD be as simple as that. A good detailing of the project will note different floor conditions. Carpet, terrazzo, slurry, a very broad range of elevations, there’s no way the door and frame supplier can assure proper installation. Just my thoughts.

  11. Bob Caron says:

    Hotel guest rooms are always a problem. They can change carpeting, padding and thresholds on a whim and never tell you. The best way to assure that you won’t end up having to cut the bottom of a couple hundred doors is to do a mock-up unit and catch it before it’s too late.

  12. David Barbaree says:

    This seems like an installation issue, not a manufacturer issue.

    To be fair to installers, the construction industry doesn’t put too much thought into installation details like this because door inspections only find these details when an AHJ is very picky (diligent).

    The door frame installer should examine the floor level, ask for details on precise floor covering thicknesses, and possibly undercut one leg of the frame to compensate for an uneven floor. This should be standard practice, but I don’t think it is. The typical installer has a matter of minutes to install the frame and keep moving in order to stay competitive. The installers who capture details like this are the ones that take personal pride and are likely not compensated for taking the time. They should be. It’s not their building or their fault that floors are not level and there should be an incentive, not a penalty, for making things right.

    If a quality general contractor only uses quality installers who are trained and consistently take the time to do this, the end user benefits. Door inspections, not just fire doors, would help the whole industry get better.

  13. Richard Page says:

    Based on the narrative I would have to place the blame on the installing contractor and supervision. The frame bottom is understood to be located at the finished sub-floor level typically concrete in a hospital. There is no rational argument for expecting the door supplier to anticipate elevating the frame. If there was, where would it end? 3/4 inches or 3 feet? Supervision is on the hook for because they would have had to provide the floor elevation to the frame installing contractor. The frame installer is going to have to prove that they were directed to place the frames at the elevation they did.

  14. Curtis Meskus says:

    So the simple fix is peel the flooring back an appropriate distance, apply a leveling compound to make a code acceptable slope, then reinstall the floor or install a rated threshold for the application that meets the accessibility requirements.

  15. Robert says:

    The one thing that is great when you do a walk on site as some talk about. the time to look and see what the condition of the floor is or what the floor will be. I am looking at a site that for the fire doors is the tile that is going on. this is where I see the problem and can talk to the GC on the 5/8 marble tile going down and be sure the frames go on as needed to meet code. that is were the tile is put down with self level and can reach great heights than the under cut can handle. it is a challenge out there on even the easy ones will bite back but sure glad for this site and have to say thanks to Lori for all her hours of time to see this work.

  16. Ginger says:

    This sounds very familiar. I have a cross corridor pair of Rite/Total style doors. The frame was installed at the floor on one jamb and above the floor at the other to attempt a square frame installation. With this I have a 1/2″ clearance at one hinge jamb, 1″ at that lock jamb, 1-1/8″ at the other leaves lock jamb and 1″ at its hinge jamb. We are re-ordering both leaves with different lengths to accommodate this. To make matters worse, when the door with 1-1/8″ clearance at the lock jamb is open 90° (where it will typically be held) clearance is 7/16″, so once we order the door 3/8″ longer it will have 1/16″ clearance at 90°. We have shown the GC the issue on the frame installation (one jamb is also twisted) and said that the frame needs to be ripped out and installed properly or at the very least the floor needs to be leveled, yet here I sit holding the bag.

  17. Vince Black says:

    Been down this road way too times.
    Laser for setting metal frames.
    Put high side on concrete, shim other leg level.
    If more than 1/8 shim (red horseshoe shim) is needed for fire door frame…alert G.C.

    Make him sign something, or tell them, we’ll come back when you level all 250,000 feet of floor.

    See how well they take that .

  18. Glenn says:

    Project managed the frames, doors & hardware for a new 14 story children’s hospital a few years back. New poured floors were out of level (as much as 3/4″ in a 8’0″ width frame). Issue was not addressed until just prior to inspection time (walls/floors finished). Although the we were not responsible the contractor wanted the us to fix the issue by field welding filler material to the frame at the floor. This included fire-rated frames. For liability reasons we refused to field modify any frame with this issue. Contractor hired their own fabricators and did the modifications on-site. AHJ allowed sweeps/door bottoms (purchased by the contractor from another supplier) and installed on the doors to bring the clearance into compliance. I find it curious how the contractor’s solution was acceptable to the inspectors and hospital management. (If I created this issue I would still be there installing new frames, doors & hardware several years later!)

  19. Bob Caldwell says:

    My preference is to specify clearances in my Div 08 door sections, and avoid the term undercut altogether. This should help in the bidding process for renovation projects, as competent contractors will walk the floors before bidding and adjust their numbers for floor leveling. On new core and shell work, our requirements for clearances are clear and the GC needs to provide an acceptable installation.

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