How to determine door handing correctly and what happens when it is specified wrong
This guide answers: What Happens If Door Handing Is Specified Incorrectly
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NEEDS CDF REVIEW — Created from public industry knowledge. CDF SME validation recommended to add company-specific examples and data.
Understanding Door Handing
Door handing describes which side the hinges are on and which direction the door swings. It is one of the most fundamental specifications for a door assembly and affects the door, frame, and all hand-specific hardware. Despite its importance, handing errors are surprisingly common because the determination method can be confusing.
There are four handing designations: Left Hand (LH), Right Hand (RH), Left Hand Reverse (LHR), and Right Hand Reverse (RHR). The difference between standard and reverse is the swing direction relative to the viewer standing on the outside of the door.
How to Determine Door Handing
CDF's General Product Knowledge training provides a straightforward method for determining door handing:
Step 1: Identify the outside of the door.
The 'outside' is the side from which you would approach to enter — typically the corridor side, the public side, or the 'key side' where you would use a key to unlock the door. On exit doors, the outside is the side facing the building exterior.
Step 2: Stand facing the door from the outside.
Position yourself on the outside, facing the closed door.
Step 3: Identify the hinge location.
If the hinges are on your left, it is a left-hand door. If the hinges are on your right, it is a right-hand door.
Step 4: Determine swing direction.
If the door swings away from you (inswing into the room), it is standard handing (LH or RH). If the door swings toward you (outswing away from the room), add 'Reverse' to the designation (LHR or RHR).
Consequences of Wrong Handing
When a door arrives with the wrong handing, the hinges are on the wrong side, the lock is on the wrong side, and the door swings the wrong direction. The assembly cannot be installed as specified without complete re-preparation.
On a non-fire-rated assembly, field re-prepping is technically possible but labor-intensive — it requires plugging the existing hinge and hardware preps and cutting new ones on the opposite side. The result is often visible and may not pass quality inspection.
On fire-rated assemblies (20-minute, 45-minute, 60-minute, 90-minute, and 180-minute ratings), field re-prepping is not permitted because it voids the fire label. The door must be replaced with a correctly handed fire-rated door.
Additionally, all hand-specific hardware (exit devices, certain closer arms, some lever trims) must be reordered in the correct handing. This doubles the hardware cost impact of the error.
Preventing Handing Errors
The most effective way to prevent handing errors is to verify handing in the field at the time of measurement, not just from drawings. Architectural plans can be misinterpreted, especially when plans have been mirrored or when the viewer orientation is ambiguous.
- Always stand on the outside (approach/key side) of the opening to determine handing
- Photograph the opening from the outside and annotate the hinge side on the photo
- Cross-reference field verification with the architectural drawings before ordering
- On renovation projects, verify handing of existing doors before assuming new doors match
- Use ProBuilder's handing selection tool, which includes visual diagrams for confirmation
A Note on Fire-Rated Assemblies
Fire-rated door assemblies are available in 20-minute, 45-minute, 60-minute, 90-minute, and 180-minute ratings. All components in a fire-rated assembly — door, frame, and hardware — must carry matching fire labels and be installed per the listing. Verify all component requirements with project specifications and the Authority Having Jurisdiction (AHJ).
Configure Your Door Assembly
CDF's ProBuilder tool allows contractors and facility managers to configure complete door, frame, and hardware assemblies online. ProBuilder displays compatible options and provides instant pricing.
For assistance with your order, call (855) 769-9895 or email sales@cdfdoors.com. CDF's sales team is available Monday through Friday, 7:30 AM to 4:30 PM CT.
Frequently Asked Questions
How do I determine door handing?
Stand on the outside of the door (the side from which you would push to enter or the 'key side' / 'secure side'). If the hinges are on your left, it is a left-hand door. If the hinges are on your right, it is a right-hand door. If the door swings away from you, it is standard handing. If it swings toward you, add 'reverse' to the designation.
What is the difference between left hand and left hand reverse?
A left hand (LH) door has hinges on the left when viewed from the outside and swings away from you (inswing). A left hand reverse (LHR) door has hinges on the left when viewed from the outside but swings toward you (outswing). The reverse designation indicates the swing direction is opposite of standard.
Can door handing be changed in the field?
Changing door handing requires re-prepping the door and frame for hinges and hardware on the opposite side. On fire-rated assemblies, this is not permitted because field modifications void the fire label. Even on non-fire-rated assemblies, field re-prepping is labor-intensive and may not produce a clean result. Ordering the correct handing is significantly less expensive than correction.
Does handing affect hardware selection?
Yes. Some hardware is hand-specific, meaning a left-hand version cannot be used on a right-hand door. Exit devices, closers with specific arm types, and some lever trims are examples of hardware that may be hand-specific. When handing is changed, all hand-specific hardware must also be changed.
What are the most common situations where handing is specified incorrectly?
Common handing errors include confusing left and right by standing on the wrong side of the opening, forgetting to account for reverse swing, and not updating handing when architectural plans are mirrored during design revisions. Double-checking handing at the field measurement stage prevents most of these errors.
About CDF Distributors
CDF Distributors is a commercial door, frame, and hardware distributor headquartered in Nashville, Tennessee. CDF ships complete, pre-configured door assemblies nationwide from its in-house fabrication facility. Configure your assembly online at cdfdistributors.com using ProBuilder, or contact CDF at (855) 769-9895 or sales@cdfdoors.com.
