Commercial Door Hardware Glossary

This is a plain-English glossary of commercial door hardware terms, with more than 130 entries. It is grouped by what the term is about: the door and frame, locks and latches, cylinders and keys, exit hardware and closers, electrified hardware and access control, and codes and ratings. Inside each group the terms run in alphabetical order.

The definitions are brand-neutral. Where a detail varies by manufacturer, we say so. Code and accessibility entries are general information only. Your fire marshal or building inspector, the authority having jurisdiction, has the final word on what your building needs.

The glossary

Door and frame

Active leaf and inactive leaf. In a pair of doors, the active leaf is the one used every day, and the inactive leaf is usually held shut by flush bolts until it is needed.

Astragal. A strip or plate on the meeting edge of one door in a pair that closes the gap between the two doors.

Backset. The distance from the edge of the door to the center of the main hole for the lever or cylinder. On bored commercial locks 2-3/4 inches is the usual backset, and 2-3/8 inches is also common. Storefront locks use different, smaller backsets, so measure before you order.

Bore (cross bore). The round hole, 2-1/8 inches across on a standard bored lock, drilled through the face of the door for the lock body and levers.

Butt hinge. The standard hinge, made of two leaves joined by a pin, with one leaf on the door and one on the frame. Commercial doors usually have three or more.

Continuous hinge. A hinge that runs the full height of the door, spreading the door weight evenly. Common on busy aluminum and steel doors.

Door bottom (sweep). A strip on the bottom edge of the door that seals the gap at the floor against air, dust and insects. Not the same as the sweep setting on a closer.

Edge bore. The 1 inch hole drilled into the edge of the door so the latch can slide into the cross bore.

Flush bolt. A bolt set into the top or bottom edge of the inactive leaf of a pair that holds it closed. Some storefront flushlocks do the same job and also take a key.

Frame (jamb and head). The frame around a door. The jambs are the vertical sides, and the head is the top. The strike is mounted on the latch-side jamb.

Hand (handing). Which side the hinges are on and which way the door swings, judged from the outside by the usual convention. Right hand (RH) and left hand (LH) doors swing away from you, and right hand reverse (RHR) and left hand reverse (LHR) doors swing toward you. Handing matters because some locks and closers are handed.

Hollow metal. Steel door and frame construction. Hardware on a hollow metal door goes into reinforced preparations, so a lock is not simply drilled in the way it can be on a wood door.

Lite. A glass panel in a door. A door with a lite may have limits on where hardware can mount.

Mullion. A post between two doors in a pair. A removable mullion lets the doors open fully for large deliveries, and rim exit devices often latch to it.

Narrow stile and wide stile. Describes how wide the vertical edge of the door is. Aluminum storefront doors usually have narrow stiles, so they need narrow-stile hardware. Each product lists a minimum stile width. See storefront door locks.

Patch fitting. A metal fitting clamped to the top and bottom corners of a frameless glass door that carries its pivots and sometimes a lock. See glass door locks.

Pivot. A hardware set that lets a door turn on a point at the top and bottom instead of on side hinges. Frameless glass doors and heavy doors often use pivots.

Rail. The horizontal piece at the top or bottom of an aluminum or glass door. Some bottom rails hold a lock bolt that goes into the floor or threshold.

Spring hinge. A hinge with a spring in it that closes the door on its own. Light-duty and not a replacement for a closer on a heavy door.

Stile. The vertical edge piece of a door. On aluminum doors it is the part the lock and exit device mount to.

Storefront. An aluminum-framed system of glass doors and windows at the front of a shop or office. See storefront door locks.

Strike (strike plate). The metal plate in the door frame that receives the latch or bolt. A standard ANSI strike plate is 4-7/8 inches long and 1-1/4 inches wide. A strike that is out of line is a common reason a door will not latch.

Threshold. The strip across the floor under the door. It seals the gap and eases the change between floor surfaces. Accessibility rules and local codes limit how high it can be.

Weatherstripping. Seals around the edges of a door that block air, dust and water. Worn weatherstripping lets air and dust in.

Locks and latches

Classroom function. The key locks and unlocks the outside lever only, and the inside lever always lets you out. Some schools now use a classroom security function, where the key works from either side. See lever handle lock functions.

Cylindrical lock. A “bored” lock whose parts sit in a 2-1/8 inch hole through the face of the door and a 1 inch hole in the edge. It is a very common commercial lever lock and is not the same as a mortise lock.

Deadbolt. A bolt that is thrown out by a key or thumbturn and stays out until it is turned back. Pushing on the end of it does not move it.

Deadlatch. A spring latch with a guard that locks the latch in place once the door is closed, so the latch cannot be pushed back. Many commercial latches work this way.

Deadlock. A lock with a deadbolt and no spring latch. On aluminum storefront doors the word usually means a narrow-stile mortise deadlock.

Faceplate. The metal plate on the edge of the door that the latch and bolt come through. Its shape (flat, radius or bevel) and size are part of how storefront locks are matched.

Finish code. A short code for the surface finish of hardware. For example, 626 (also written US26D) is satin chrome, a very common commercial finish.

Function. What the levers, key and thumbturn do on each side of the door, such as passage, privacy, classroom, storeroom or office. Functions on cylindrical locks are set at the factory and usually cannot be changed in the field. See lever handle lock functions.

Grade (BHMA grade). A durability rating for locks. Grade 1 is the heaviest duty and Grade 3 the lightest. For bored locks the test cycles are 1,000,000, 400,000 and 200,000 for Grades 1, 2 and 3. A grade rates durability, not resistance to forced entry.

Hookbolt. A bolt shaped like a hook that engages the strike and resists prying and parting. Used on some storefront and sliding-door locks.

Indicator lock (occupancy lock). A privacy lock with a small window that shows vacant or occupied from outside. It should have an emergency release on the outside. See restroom indicator locks.

Latch (latchbolt). The spring-loaded bolt with a sloped face that pushes in as the door closes and springs out into the strike. The lever pulls it back.

Lever. A handle you push down to open the door. Levers are used on commercial doors because they work without gripping or twisting.

Mortise lock. A lock whose body sits in a rectangular pocket cut into the door edge. It is heavy-duty, can combine a latch and deadbolt, and offers many functions. See mortise locks.

Office (entrance) function. The door can be locked or left unlocked from inside the room, and the key works from outside. How the lock is set from inside varies by brand.

Passage function. No lock at all. Both levers always work. Used on interior corridor and closet doors.

Privacy function. A button or turn on the inside locks the outside lever. There is no key, and an emergency release on the outside opens it.

Rim lock. A lock mounted on the surface of the door instead of inside it. Rim exit devices work this way.

Rose and escutcheon. The round plate (rose) or longer plate (escutcheon) behind a lever or knob that covers the hole in the door.

Storeroom function. The outside lever is always locked, the key opens it, and the inside lever always lets you out. It has no unlocked mode, so it suits storerooms, mechanical rooms and server closets.

Thumbturn. A small turn on the inside of the door that works a deadbolt or lock without a key.

Throw. How far a bolt or latch extends out of the lock. A deadbolt with a longer throw reaches deeper into the frame.

Trim. The visible parts, such as levers, pulls, escutcheons and key cylinders, that operate a lock or exit device from the outside or inside. Trim usually has to match the lock body or device.

Tubular lock. A lighter bored lock that uses a single large hole through the door face and a separate hole for the latch. It is usually used on interior doors that do not need a key.

Cylinders and keys

Bitting. The pattern of cuts on a key, usually written as a string of depth numbers. A bitting list records the cuts for every key and lock in a system.

Cam. The small arm or plate on the back of a cylinder that turns with the key and moves the bolt or latch. Cams differ by lock, which is why a cylinder must be matched to the lock it goes in.

Change key. The key that opens one lock, or one small group of locks, in a master key system. Master keys sit above it.

Construction core. A temporary interchangeable core, keyed alike, used while a building is being finished. When the work is done, the control key removes the temporary cores and permanent ones go in.

Control key. The key that removes or installs an interchangeable core. It does not unlock the door. See IC core locks.

Core. The removable center of an interchangeable-core cylinder, containing the plug, pins and springs. A core can be swapped out without taking the lock apart.

Cylinder. The part of a lock with the keyway. The key turns it, and it moves a cam or tailpiece to work the lock. Common types are mortise cylinders, rim cylinders and cylinders inside key-in-lever locks.

Grand master key. A key that opens every lock in several master groups. In a large building it might open all the floors or all the departments.

IC core (interchangeable core). A cylinder core that a control key can release from its housing, so it can be swapped or recombinated without disassembling the lock. Useful when keys change hands often. See IC core locks.

Key blank. An uncut key of a given keyway. Blanks for restricted keyways are controlled by the manufacturer.

Key control. How a business controls who gets keys and who can copy them. Key control usually combines a restricted keyway, a signed record of who holds each key, and limited ways to order new keys. A “Do Not Duplicate” stamp alone does not stop copying.

Keyed alike. Several locks set to open with the same key. Useful for the doors one person uses together.

Keyed different. Each lock opens only with its own key. No two keys are alike unless a master key system makes them related.

Keying schedule. The written plan for a key system: which keys open which doors, and how the cuts are assigned. It is the document that makes it possible to add doors later without starting over.

Keyway. The shaped slot in a cylinder that only keys with the matching profile can enter. Different manufacturers and lines use different keyways, and each has its own blanks.

LFIC and FSIC. Large-format interchangeable core. The core is bigger than an SFIC core, and the size is specific to each maker, so cores generally do not swap between brands. Some makers use their own name, such as full-size interchangeable core (FSIC).

MACS (maximum adjacent cut specification). The largest depth difference allowed between two neighboring cuts on a key. It varies by manufacturer and keyway, and it limits how a master key system can be designed.

Master key. A key that opens all the locks in a group, in addition to each lock’s own change key. See master key systems.

Master key system. A planned key hierarchy in which different keys open different sets of locks. Typical levels are change keys, submasters, a master and a grand master. The more levels, the more convenience and also the more risk if a key is lost. See master key systems.

Mortise cylinder. A round, threaded cylinder that screws into a mortise lock, a storefront lock or an exit device trim. Its length and cam must match the lock.

Operating key. The key people use every day to lock and unlock. It can be a change key, a master key or a grand master key. Not the same as a control key.

Pin tumbler. The most common cylinder design. Spring-loaded pin stacks sit in the plug and the cylinder body, and the correct key lifts each stack so the gap between the pins lines up with the shear line and the plug can turn.

Rekey. To change the internal parts of a cylinder so a new key works and the old keys stop working. The lock stays on the door. See commercial rekey.

Restricted keyway. A keyway whose blanks and key copies are controlled by the manufacturer, usually with a patent and an authorization process. It reduces casual copying but cannot prevent it completely.

Rim cylinder. A cylinder that mounts through the face of the door, and connects to a rim lock or exit device with a tailpiece.

SFIC (small format interchangeable core). The figure-eight shaped interchangeable core that originated with Best. Many makers produce cores in this format, so SFIC cores from different brands often fit the same housing.

Shear line. The gap between the plug and the cylinder body. When the pins line up at the shear line, the plug turns. A master key system adds extra shear lines so more than one key can work.

Sidebar. In some high-security cylinders, an extra locking bar beside the pins. The side cuts on the key must line up with it before the plug turns.

Submaster key. A key between the change key and the master key, for a department, a floor or a group of tenants.

Exit hardware and closers

Alarmed exit device. An exit device that sounds a horn or siren when someone pushes it, used where a door should be exit-only and staff want to know when it opens.

Automatic closing (self-closing). A door that closes by itself from any open position. Fire doors must do this. A closer provides it.

Backcheck. A closer setting that slows the door near the end of its opening swing so it does not slam into a wall or stop. It does not affect closing speed.

Closer (door closer). A spring and hydraulic device that closes a door and controls how fast it moves. See door closers.

Concealed vertical rod (CVR). An exit device whose latching rods run inside the door, so the face of the door stays clean. It latches at the top and bottom of the door.

Delayed egress. A lock arrangement that holds the door for a short time after someone pushes the bar while an alarm sounds. It is allowed only in specific cases and only with the approval of the authority having jurisdiction.

Dogging. A way to hold the pushbar of an exit device in, so the latch stays retracted and the door opens freely. It is done with a hex key or a cylinder. Mechanical dogging is not allowed on fire exit hardware.

Dummy trim. A fixed pull or lever on the outside of an exit device door that does not retract the latch. The door can be opened from outside only if the latch has been held back.

Exit device (panic hardware). A horizontal bar or touchpad on the inside of a door that releases the latch when pushed. Used on exit doors in many buildings. See panic bars and exit devices.

Fire exit hardware. An exit device that has also passed fire testing, so it can be used on a fire-rated door. It cannot be mechanically dogged down. Many models carry an F suffix on the model number.

Floor closer. A closer set into the floor under a door, connected to a pivot. Common with frameless glass doors.

Hold-open. A closer arm or stop that keeps a door open. On fire doors a hold-open generally has to be a listed type, usually one that releases when the fire alarm sounds, and the fire marshal decides what is acceptable.

Latch speed. The closer setting that controls the last few degrees of closing. It is what makes the door latch without slamming.

Night latch. An exit device function where the key on the outside retracts the latch, so the door can be opened from outside with a key only.

Overhead stop. A device on the door or frame that limits how far the door opens, and may also hold it open.

Parallel arm, regular arm and top jamb arm. Three ways of mounting a surface closer. Which one fits depends on the side of the door the closer is on and the frame around it.

Pushbar (touchpad). The bar or pad across the inside of the door that you press to release the latch.

Rim device. An exit device mounted on the face of the door that latches into a strike on the frame. It is the most common type for single doors.

Spring size. The strength of the spring inside a surface closer, usually a number from 1 to 6. It sets the closing force and must match the door width. Valves change speed, not opening force.

Surface vertical rod (SVR). An exit device with rods on the surface of the door that latch at the top and bottom, used on pairs of doors with no center post.

Sweep (closer). The closer setting that controls the main part of the closing swing. On most closers, turning it clockwise slows the door. Not the same as a door sweep at the bottom of the door.

Electrified hardware and access control

Access control. A system that decides who can open which door and when, using keypads, cards, fobs or phones instead of, or alongside, keys. See access control systems.

Access controller. The unit that receives the signal from a reader, decides whether to allow the person in, and tells the lock or strike to release.

Audit trail. A record of who opened which door and when. Available on networked systems and some standalone locks. Not every lock keeps one.

Credential. What a person presents to open a door: a code, a card, a fob, or a phone.

Door position switch. A sensor that tells the system whether the door is open or closed. It lets the system report a door left ajar or forced open.

Electric latch retraction. A feature on some exit devices where a small motor or solenoid pulls the latch back on a signal, so the door can be released remotely. It is fail-secure.

Electric strike. An electrically controlled strike in the door frame. When it receives a signal, it releases the latch so the door can be pushed or pulled open. It comes in fail-safe and fail-secure types. See electric strikes and electrified locks.

Electrified lock or trim. A lock or exit device trim in which power controls whether the outside lever or handle works. Inside, the lever or pushbar normally still lets people leave.

Electromagnetic lock (mag lock). A magnet on the frame that holds a plate on the door closed. It releases when power is cut, so it is fail-safe. Because it has no latch to retract, codes generally require extra release devices for people leaving.

Fail-safe. A lock that unlocks when power is lost. Power holds it locked.

Fail-secure. A lock that stays locked when power is lost. Power is needed to unlock it. On most products people can still leave through the lever or pushbar on the inside.

Fire alarm release. A connection between the building’s fire alarm and electrically locked doors, so that where required the doors unlock when the alarm activates.

Keypad lock. A lock that opens with a code. Some are standalone and store codes in the lock, and others connect to a system.

Mechanical pushbutton lock. A lock with a row of buttons and a code, and no batteries or wiring. Common on gates and back doors. See Simplex pushbutton lock repair.

OSDP. Open Supervised Device Protocol, a newer standard for two-way communication between a reader and a controller, with optional encryption. It can also report if a reader has been tampered with.

Power supply. A unit that converts building power to the low voltage a lock or strike needs, often with a backup battery. Wire gauge and voltage drop on long runs are part of planning one.

Proximity (prox) card. A simple card or fob that a reader detects when it is held close. Many readers use 125 kHz for this.

Reader. The device at the door that reads a card, fob, phone or keypad entry.

Request to exit (REX). A switch or motion sensor on the inside of a door that tells the system someone is leaving on purpose, so the door does not report a forced entry. On some arrangements it is also part of how a locked door releases for people leaving.

Smart card. A card with a chip that can hold more than a simple ID number. Features differ by card type and system, so ask what a given card and reader support.

Standalone lock. An electronic lock that keeps its own codes or credentials and is programmed at the door, instead of through a central system.

Wiegand. An older, widely used signal format between reader and controller. It sends data one way and without encryption, and it works over shorter cable runs than newer protocols.

Codes and ratings

ADA (Americans with Disabilities Act). The law behind accessibility standards for buildings. For door hardware, the 2010 ADA Standards call for parts that work with one hand, without tight grasping, pinching or twisting of the wrist, mounted between 34 and 48 inches above the floor. Interior hinged doors other than fire doors are limited to 5 pounds of opening force. Local rules can add requirements.

AHJ (authority having jurisdiction). The person or office that enforces the code where you are, such as the fire marshal or the building official. Their interpretation is the one that counts.

BHMA and ANSI. The Builders Hardware Manufacturers Association writes standards for hardware, and ANSI is the body that approves them as American National Standards. Lock grades come from these standards.

Egress. The way out of a building. Doors on an egress route generally have to open from the inside without a key or special knowledge, with exceptions that the authority having jurisdiction decides.

Fire door assembly. The door, frame, hinges, closer, latch and other hardware that together carry a fire rating. Changing or removing a part can affect the rating.

Fire rating. How long a fire door assembly is tested to resist fire, stated in hours or fractions of an hour. A common rating on commercial hardware is 3-hour.

Fire department key box. A locked box on the outside of a building holding keys for the fire department, often sold under the Knox-Box name. If the locks are rekeyed, the keys in the box have to be updated too.

Label and listing. A permanent label on a fire door or frame shows it was tested and listed by a laboratory such as UL. Painting over or removing a label can cause problems at an inspection.

NFPA 80. The standard for fire doors and similar openings. It covers how fire door assemblies are installed and maintained, including that they close and latch every time. The authority having jurisdiction decides how it applies to your building.

Occupant load. The number of people the code allows in a space. For some occupancy types, a higher occupant load triggers the requirement for panic hardware on exit doors.

Positive latching. The requirement that a fire door’s latch fully engages every time the door closes. A door that only rests against the frame does not meet it.

UL rating. A listing from UL, a safety testing organization, showing a product passed a standard’s tests. For example, UL 305 covers panic hardware, and UL 10C is a fire test used for fire exit hardware.

Where to go next

If a term here describes something on one of your doors and you are not sure what you have, send us a photo. Our commercial lock brands guide explains how to identify what is on the door, and the commercial door hardware checklist walks you through your building. When you are ready for a price, use the commercial quote page. The commercial locksmith overview lists what we do for businesses, and for key types in general see every type of key explained. Our door hardware page covers the basics for both homes and businesses.

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