Commercial door and hardware terminology covers the specialized vocabulary used across hollow metal doors, steel frames, locksets, hinges, closers, and fire-rated assemblies. This reference guide defines over 100 terms organized by category, giving contractors, facility managers, and specifiers a single resource for understanding the language used in door schedules, hardware specifications, and architectural drawings. Each category below groups related terms so you can quickly find the definition you need during takeoffs, submittals, or field installation.
CDF Distributors provides complete commercial door, frame, and hardware assemblies shipped from its Nashville, Tennessee headquarters. You can configure and order online using CDF’s ProBuilder tool at cdfdistributors.com. For assistance selecting the correct components for your project, call (855) 769-9895 or email sales@cdfdoors.com.
About This Guide
This glossary is compiled from CDF Distributors’ technical documentation, industry standards published by the Steel Door Institute (SDI), the Door and Hardware Institute (DHI), and NFPA 80 fire door assembly requirements. CDF’s engineering and sales teams use these terms daily when fabricating hollow metal assemblies, consulting on hardware schedules, and supporting contractors in the field. The definitions reflect current commercial construction practice in the United States.
Steel Gauge and Door Prep Terms
Steel gauge numbers and door prep designations appear on virtually every commercial door schedule. Gauge numbers indicate the thickness of the steel used in doors and frames, while prep numbers specify the cutouts required for specific lock and hardware types. The following table defines the most common gauge and prep terms.
Term | Definition |
12 Gauge (12 ga.) | Steel thickness of 0.1046 inches. Used for heavy-duty frames in high-traffic or high-security applications. |
14 Gauge (14 ga.) | Steel thickness of 0.0747 inches. Standard gauge for commercial hollow metal frames. |
16 Gauge (16 ga.) | Steel thickness of 0.0598 inches. Common for standard commercial hollow metal doors. |
18 Gauge (18 ga.) | Steel thickness of 0.0478 inches. Used for lighter-duty commercial doors and some interior frames. |
20 Gauge (20 ga.) | Steel thickness of 0.0359 inches. Used for door face sheets in some hollow metal door constructions. |
161 Prep | A 2-1/8” diameter cutout (bore hole) in a door for bored/cylindrical locksets. This is the standard prep for lever-handle locksets. |
86 Edge Prep | An 8” cutout in the edge of a door to accept a mortise lock body. Used when the hardware schedule specifies mortise locksets. |
Hinge Prep | Pre-punched or pre-mortised hinge locations on doors and frames. Standard commercial doors use three hinges; doors over 7’0” may require four. |
Closer Prep | Reinforcement and/or pre-drilled holes in a door or frame to accept a door closer. Closer reinforcement provides the structural backing needed to support repeated closer operation. |
Door Components
Commercial doors are manufactured with specific components that differ from residential construction. Understanding these components is essential when reading hardware schedules, ordering replacements, or specifying new assemblies. The terms below cover hollow metal and wood door construction.
Term | Definition |
Active Door | The leaf of a pair of doors (double doors) that opens first and contains the locking or latching device. The other leaf is called the inactive door. |
Inactive Door | The leaf of a pair of doors that is normally fixed in place with flush bolts or surface bolts. It opens only after the bolts are released. |
Astragal | A strip of steel or wood that covers or closes the gap between the edges of a pair of doors. Some types overlap; others meet at the center line of the gap. |
Beveled Edge | A door edge that is not at a 90-degree angle to the face. Standard bevel is 1/8 inch in 2 inches. The narrow side contacts the stop when the door is closed. |
Borrowed Lite | A four-sided steel frame that is glazed (contains glass) but does not include a door. Often referred to as a steel window frame or sidelight frame. |
Door Lite | A glass panel or window set into a door. Lites are available in various sizes and may require fire-rated glazing in rated assemblies. |
Flush Door | A door with smooth, flat faces on both sides. Both hollow metal and wood commercial doors are commonly manufactured as flush doors. |
Hollow Metal Door | A door constructed from steel sheets formed around a core material. The steel face sheets are typically 16 or 18 gauge. |
Mineral Core Door | A wood door with a core made of mineral composition material, commonly used in fire-rated assemblies up to 90 minutes. |
Stile | The vertical edge member of a door. The hinge stile receives the hinges; the lock stile receives the lockset. |
Rail | A horizontal structural member of a door. Top rail and bottom rail define the upper and lower edges. |
Door Silencer | A small rubber bumper installed in the frame stop to cushion the door when it closes and reduce noise. |
Louver | A ventilation opening in a door consisting of angled slats that allow airflow while maintaining visual privacy. Louvers must be fire-rated in fire-rated door assemblies. |
Undercut | The clearance between the bottom of a door and the finished floor. Standard undercut is 3/4”; may vary depending on floor finish and ADA requirements. |
Frame Components
Commercial steel frames consist of multiple components that work together to support the door, receive hardware, and integrate with the surrounding wall construction. The following terms describe the parts and features of hollow metal door frames.
Term | Definition |
Head (Header) | The horizontal top member of a door frame that spans the width of the opening. |
Jamb | A vertical side member of a door frame. Each frame has a hinge jamb and a strike jamb. |
Hinge Jamb | The jamb that receives the hinges and supports the door’s weight. |
Strike Jamb | The jamb that receives the strike plate for the locking or latching device. |
Rabbet (Stop) | The recessed portion of a frame profile against which the door closes. Also called the door stop. Frames may have rabbets sized for 1-3/8” or 1-3/4” doors. |
Cased Opening | A steel frame with no stops (no rabbet). Used for openings that do not receive a door. |
Sill | The bottom horizontal member of a frame, used primarily in exterior or specialty frames. Most interior commercial frames do not include a sill. |
Throat | The inside dimension of the frame from the back of one face to the back of the other face. Must match the wall thickness exactly. |
Face | The visible front surface of a frame jamb or head after installation. |
Return | The portion of a frame that wraps back toward the wall. In a drywall wrap frame, the returns wrap around the drywall edges. |
Anchor | A device used to attach a door frame to the surrounding structure or wall. Types include base anchors, compression anchors, combination anchors, and masonry anchors. |
Base Anchor | A piece of metal attached to the base of a door frame to secure the frame to the floor. |
Compression Anchor | An anchor located at the top of each jamb in a drywall wrap frame. A flange presses against wall studs to hold the frame in position. |
Combination Anchor | A device for anchoring a frame to a wall constructed with either wood or metal studs. |
Masonry Anchor | A wire or strap anchor welded to the back of a frame for embedding in mortar joints during masonry wall construction. |
Closer Reinforcement | A reinforcing plate inside a door or frame that provides additional strength for attachment of door closers. |
Drywall Wrap Frame | A three-piece steel frame designed to wrap around a finished drywall opening. Consists of a head and two jambs that interlock at the corners. |
Welded Frame | A one-piece frame in which the head and jambs are factory-welded together. Typically used in masonry or concrete wall construction. |
Knock-Down (KD) Frame | A frame shipped in three separate pieces (head and two jambs) that are assembled in the field. Drywall wrap frames are a common type of KD frame. |
Hardware Types
Commercial door hardware includes all of the devices that control how a door operates, locks, and closes. Hardware is specified in a hardware schedule or hardware set, which lists every device for each opening in a project. The following terms cover the major categories of commercial door hardware.
Term | Definition |
Lockset | A complete locking device including the lock body, trim (handles or levers), and strike. Commercial locksets are available in bored (cylindrical) and mortise configurations. |
Cylindrical Lockset (Bored Lock) | A lockset installed through a bored hole (161 prep) in the door face. The most common lockset type in standard commercial applications. |
Mortise Lock | A lock installed in a rectangular pocket (mortise) cut into the edge of the door (86 edge prep). Provides heavier-duty operation than cylindrical locksets. |
Deadbolt | A lock bolt that is moved into the locked position by a key or thumb turn, with no spring action. Provides higher security than a latchbolt alone. |
Latchbolt | A spring-loaded bolt with an angled face that retracts when the door closes against the strike and extends automatically to hold the door shut. |
Exit Device (Panic Hardware) | A door-locking device that allows immediate egress by pressing a bar or paddle on the interior side. Required by code on doors in the path of egress. |
Door Closer | A hydraulic or pneumatic device that controls the closing speed and force of a door. Mounted on the door, frame, or concealed in the door header. |
Coordinator | A device used on a pair of doors to ensure that the inactive leaf closes before the active leaf. Necessary when both doors have closers and overlapping astragals. |
Flush Bolt | A bolt installed flush into the edge or face of the inactive door in a pair. Used to secure the inactive leaf at the head and/or sill. |
Surface Bolt | A bolt mounted on the surface of a door (not mortised in). Used to secure the inactive leaf of a pair of doors. |
Pivot | A door-hanging device that uses a top and bottom pivot point instead of hinges mounted on the side. Used for heavy or wide doors. |
Threshold | A raised member at the bottom of a door opening, typically used at exterior openings. Provides weather sealing and ADA-compliant transitions. |
Weatherstripping | Gasket or seal material applied to the door or frame to prevent air, light, smoke, or water infiltration around the door perimeter. |
Kick Plate | A protective plate mounted on the bottom push side of a door to resist damage from foot traffic and carts. |
Push Plate / Pull Handle | Trim devices mounted on doors that do not have lever or knob hardware. Push plates on the push side; pull handles on the pull side. |
Door Stop | A device that prevents a door from opening beyond a desired point, protecting walls and hardware from impact damage. |
Lock Functions
Lock function describes how a lockset operates, specifically which side locks, which side is always free, and how the lock is controlled. Lock functions are standardized across the industry, and each function has a specific use case. Specifying the wrong lock function can create code violations or security gaps. The table below lists the most common commercial lock functions.
Term | Definition |
Passage (Function F75) | Latchbolt operated by lever from both sides at all times. No locking capability. Used for closets, corridors, and interior rooms that do not require locking. |
Privacy (Function F76) | Latchbolt operated by lever from both sides. Inside button or turn locks the outside lever. Emergency release on outside. Used for restrooms and break rooms. |
Entry/Office (Function F82) | Latchbolt operated by lever from both sides. Deadlocking latchbolt. Outside lever locked/unlocked by key or inside button. Used for offices and interior rooms. |
Classroom (Function F84) | Latchbolt operated by lever from both sides. Outside lever locked/unlocked by key only. Inside lever always free for egress. Used for classrooms and meeting rooms. |
Storeroom (Function F86) | Latchbolt operated by lever from inside at all times. Outside lever always locked; entry by key only. Used for storerooms, mechanical rooms, and supply closets. |
Vestibule / Apartment (Function F88) | Latchbolt operated by lever from both sides. Deadlocking latchbolt. Outside lever locked by key; inside lever always free. Key retracts latchbolt from outside. |
Dummy Trim | Non-operating trim (lever or knob) that does not connect to any lock mechanism. Used on inactive doors or for decorative purposes. |
Cam | A rotating piece attached to the end of a cylinder plug to engage the locking mechanism within a lockset or deadbolt. |
Keying Terms
Keying systems in commercial buildings control which keys open which doors. A properly planned keying system balances security with convenience, allowing building managers to maintain access control across departments, floors, or entire facilities. The following terms describe the most common keying concepts.
Term | Definition |
Change Key (Day Key) | A key on the lowest level of a master keying system. Change keys typically provide access to one or two doors and are issued to individual personnel. |
Master Key | A key that operates all locks within a specific group or system. A master key opens every lock that the individual change keys open. |
Grand Master Key | A key that operates all locks in an entire master keying system, across multiple master key groups. |
Construction Master Key | A temporary key used during the construction phase. Once the building is turned over, the construction master is voided and the permanent keying system takes effect. |
Key Cylinder | The component of a lock that accepts the key and translates the key rotation into lock operation. Available in several types including mortise cylinders and rim cylinders. |
Keyed Alike (KA) | A group of locks that all operate with the same key. Used when the same person needs access to multiple doors without carrying multiple keys. |
Keyed Different (KD) | Each lock in a group operates with its own unique key. No key opens any other lock in the group. |
Hinge Types
Hinges are the primary door-hanging device in commercial construction. The type of hinge specified depends on the door weight, frequency of use, fire rating requirements, and security needs. All hinges for fire-rated openings must be steel, bearing-type hinges. The following table covers the most common commercial hinge types.
Term | Definition |
Butt Hinge (Mortise Hinge) | A hinge designed for mortising (recessing) into the edge of a door and into the rabbet of a door frame. The standard hinge type for commercial hollow metal and wood doors. |
Ball Bearing Hinge | A butt hinge with ball bearings between the hinge knuckles to reduce friction. Required for doors with closers and for all fire-rated door assemblies. |
Continuous Hinge (Piano Hinge) | A hinge that extends the full length of a door. Distributes the door’s weight across the entire height of the frame, reducing hinge wear and frame stress. Common on high-traffic and heavy doors. |
Spring Hinge | A hinge with a built-in spring mechanism that pulls the door closed automatically. Can be used in place of a door closer in some applications. |
Raised Barrel Hinge | A hinge with the barrel (knuckle) offset from the face of the door. Used to provide additional clearance for the door to swing past trim or casing. |
Non-Removable Pin (NRP) Hinge | A hinge with a pin that cannot be removed when the door is closed. Required on outswing doors in secure applications to prevent hinge pin removal from the exterior. |
Hospital Tip Hinge | A hinge with a slightly rounded, flat tip that reduces the gap between the hinge leaves. Used in healthcare settings where infection control and ligature resistance are considerations. |
Hinge Knuckle | The interlocking cylindrical portion of a hinge through which the pin passes. The number and size of knuckles affect load capacity and durability. |
Fire Rating Terms
Fire-rated door assemblies are required by building codes at specific locations to prevent the spread of fire and smoke. A fire-rated assembly includes the door, frame, hardware, glazing, and any other components, all of which must carry matching fire labels. Fire ratings are assigned in five standard levels: 20-minute, 45-minute, 60-minute, 90-minute, and 3-hour (180-minute). The following terms define key fire rating concepts.
Term | Definition |
20-Minute Rating | The lowest standard fire rating. Used for corridor doors and smoke barriers where a limited fire resistance period is required. Both hollow metal and wood doors can achieve this rating. |
45-Minute Rating | Used for openings in 1-hour rated corridor walls and room separations. Both hollow metal and wood doors are available at this rating level. |
60-Minute Rating (1-Hour) | Used for openings in 1-hour rated walls, including exit enclosures and exit passageways. Available in both hollow metal and mineral core wood door assemblies. |
90-Minute Rating (1-1/2-Hour) | Used for openings in 2-hour rated walls, including stairwell enclosures and shaft walls. Both hollow metal and mineral core wood doors can achieve this rating. This is the maximum rating for drywall wrap frames. |
3-Hour Rating (180-Minute) | The highest standard fire rating for door assemblies. Required for openings in walls with a fire resistance rating of 3 hours or more. Assemblies at this level must use masonry frames; drywall wrap frames cannot achieve a 3-hour rating. |
Fire Label | A permanent label riveted or attached to a fire-rated door, frame, or hardware component certifying that it has been tested and listed to the specified fire rating. Labels are required by NFPA 80 and the Authority Having Jurisdiction (AHJ). |
Fire-Rated Assembly | The complete combination of a fire-rated door, frame, hardware, glazing, and seals that together provide the required fire resistance. All components must carry matching or compatible fire labels. |
Fire-Rated Glazing | Glass or transparent material tested and listed for use in fire-rated door assemblies. Fire-rated glazing has maximum size limitations depending on the rating level. |
Positive Pressure Fire Test | A fire test method (UL 10C / NFPA 252) that applies positive furnace pressure to the assembly during the test. This is the current standard test method for fire door assemblies. |
Temperature Rise Door | A fire-rated door that limits the temperature rise on the unexposed face to 450 degrees Fahrenheit or 250 degrees Fahrenheit within 30 minutes. Required in specific locations such as stairwell enclosures. |
NFPA 80 | National Fire Protection Association Standard 80: Standard for Fire Doors and Other Opening Protectives. The primary standard governing inspection, testing, and maintenance of fire door assemblies. |
Authority Having Jurisdiction (AHJ) | The organization, office, or individual responsible for enforcing code requirements related to fire-rated assemblies. The AHJ has final authority on fire-rated assembly compliance. |
Smoke Seal (Gasketing) | Material applied to the door or frame perimeter to limit smoke passage through the opening. Required on fire-rated smoke barrier openings per code. |
Finish Designations
Commercial door hardware and hollow metal assemblies are specified with standardized finish codes. These codes identify the color, texture, and coating type for doors, frames, and hardware. Matching finish designations across all components ensures a consistent appearance. The following table lists the most commonly specified finishes in commercial construction.
Term | Definition |
US26D (626) | Satin chromium plated. The most commonly specified commercial hardware finish. Provides a matte silver appearance with good durability. |
US26 (625) | Bright chromium plated. A polished silver finish. Less common than satin chrome in commercial applications. |
US32D (630) | Satin stainless steel. A matte finish on stainless steel hardware. Preferred in healthcare, food service, and corrosive environments. |
US32 (629) | Bright stainless steel. A polished finish on stainless steel hardware. |
US10 (612) | Satin bronze plated. A matte bronze finish used in traditional and institutional applications. |
US10B (613) | Dark oxidized satin bronze. A darker variation of the bronze finish. |
US3 (605) | Bright brass plated. A polished gold-tone finish. |
US4 (606) | Satin brass plated. A matte gold-tone finish. |
US19 (607) | Flat black coated. A matte black finish increasingly specified in modern commercial interiors. |
Prime / Primed | Factory-applied primer coat on hollow metal doors and frames, ready for field painting. The standard finish for hollow metal assemblies unless a factory finish is specified. |
Galvanized | A zinc coating applied to steel to prevent corrosion. Used on frames and doors in exterior, humid, or wet environments. |
Powder Coat | A factory-applied colored finish baked onto hollow metal doors and frames. Available in a wide range of colors. More durable than field-applied paint. |
Frame and Wall Construction Terms
Frame installation and wall construction terms describe how frames are anchored, how walls are built, and how the frame integrates with the surrounding structure. These terms appear frequently in architectural specifications and on construction drawings.
Term | Definition |
Rough Opening | The opening in a wall into which a door frame is installed. For drywall wrap frames, the rough opening is typically the door width plus 2 inches by the door height plus 1 inch. |
Wall Thickness | The total thickness of the wall assembly, including studs and finish materials on both sides. Frame throat depth must match wall thickness exactly. |
Metal Stud Wall | A wall constructed with cold-formed steel studs and track, typically finished with gypsum board (drywall) on each side. |
Masonry Wall | A wall constructed with concrete masonry units (CMU), brick, or stone. Frames for masonry walls are set during wall construction, not after. |
Plumb | Perfectly vertical. A plumb frame jamb is critical for proper door operation and latch engagement. |
Level | Perfectly horizontal. The frame head must be level for the door to operate properly. |
Square | A condition where corners form 90-degree angles and opposite sides are parallel. A square frame produces consistent gaps between the door and frame on all sides. |
Shim | A thin wedge or piece of material used to fill gaps and make fine adjustments when leveling and squaring a frame in a rough opening. |
Backset (Lock) | The distance from the edge of a door to the center of the hole drilled for a lockset or deadbolt. Standard commercial backsets are 2-3/4” for bored locks. |
Additional Industry Terms
The following terms appear in specifications, submittals, and hardware schedules but do not fit neatly into a single category above. They cover standards organizations, measurement conventions, and operational concepts that contractors encounter across commercial door projects.
Term | Definition |
SDI | Steel Door Institute. The industry organization that publishes standards for steel doors and frames, including recommended gauges, tolerances, and installation practices. |
DHI | Door and Hardware Institute. The professional association for the architectural openings industry. DHI administers the AHC (Architectural Hardware Consultant) certification. |
BHMA | Builders Hardware Manufacturers Association. Publishes performance standards (ANSI/BHMA) for commercial door hardware including locksets, closers, hinges, and exit devices. |
Door Schedule | A document listing every door in a project with its size, material, fire rating, frame type, and hardware set. Typically included in the architectural drawings. |
Hardware Schedule (Hardware Set) | A document listing every hardware item for each opening in a project. Organized by hardware set number corresponding to the door schedule. |
Hand / Handing | The swing direction of a door determined by standing on the outside (key side) and noting which side the hinges are on. Right Hand (RH): hinges on the right. Left Hand (LH): hinges on the left. Reverse (RHR/LHR) indicates the door swings toward you. |
Pair (Double Doors) | Two doors in a single frame. One is the active leaf and one is the inactive leaf, unless both are specified as active (equal pair). |
Transom | A panel (glazed or solid) above a door within the same frame. Used to increase light transfer or to fill the space between the door head and the ceiling. |
Sidelight | A glazed or solid panel adjacent to a door within a frame assembly. Provides visibility or additional light at the opening. |
ADA Compliance | Americans with Disabilities Act requirements for door openings, including minimum clear width (32”), maximum opening force (5 lbf for interior doors), and maximum closer sweep time. |
Configure Your Door Assembly
CDF’s ProBuilder tool allows contractors and facility managers to configure complete door, frame, and hardware assemblies online. ProBuilder uses the terminology defined in this guide throughout the configuration process, displaying compatible options for each selection. During configuration, ProBuilder automatically applies correct preps, gauges, and fire rating requirements based on your selections.
For assistance with terminology on your project’s door schedule or hardware specifications, 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
What is the difference between a cylindrical lockset and a mortise lock?
A cylindrical lockset installs through a round bored hole (161 prep, 2-1/8” diameter) in the door face. A mortise lock installs into a rectangular pocket (86 edge prep, 8” cutout) cut into the edge of the door. Mortise locks are heavier duty and offer more function options, but they require a thicker door stile to accommodate the lock body. Both types are used in commercial applications.
What do the fire rating levels mean for commercial doors?
Fire ratings indicate how long an assembly can resist fire in a standard test. The five standard levels are 20-minute, 45-minute, 60-minute, 90-minute, and 3-hour (180-minute). The required rating depends on the wall’s fire resistance rating and the opening’s location in the building. All components in the assembly, including door, frame, hardware, and glazing, must carry matching or compatible fire labels.
What is the difference between a drywall wrap frame and a welded frame?
A drywall wrap frame ships in three pieces (head and two jambs) and installs after the wall is finished by wrapping around the drywall edges. A welded frame is a one-piece unit with the head and jambs factory-welded together, typically set during wall construction in masonry or concrete applications. Drywall wrap frames are standard for interior commercial applications in metal stud walls.
What does "hand" or "handing" mean on a door schedule?
Handing describes the swing direction of a door. Stand on the outside (key side) of the door and note which side the hinges are on. Hinges on the right means Right Hand (RH); hinges on the left means Left Hand (LH). If the door swings toward you, add "Reverse" (RHR or LHR). Correct handing is essential when ordering locksets, exit devices, and closers because many hardware items are hand-specific.
What gauge steel should I specify for commercial door frames?
Standard commercial interior frames are typically 16 gauge (0.0598”) or 14 gauge (0.0747”). For high-traffic areas, high-security applications, or frames receiving heavy hardware, 14 gauge or 12 gauge (0.1046”) is appropriate. The project specifications or architect typically dictates the required gauge.
What is a 161 prep and an 86 edge prep?
A 161 prep is a 2-1/8” diameter hole bored through the face of a door to accept a cylindrical (bored) lockset. An 86 edge prep is an 8” rectangular cutout in the edge of a door to accept a mortise lock body. The prep type is determined by the lockset type specified in the hardware schedule. Doors must be ordered with the correct prep to match the specified hardware.
Do all components in a fire-rated opening need to be fire-rated?
Yes. NFPA 80 requires that every component in a fire-rated opening carry a matching or compatible fire label. This includes the door, frame, hinges, lockset, closer, glazing, louvers, smoke seals, and any other component installed in the assembly. Missing or mismatched labels can cause the assembly to fail inspection by the Authority Having Jurisdiction (AHJ). Fire labels are available at all five standard rating levels: 20-minute, 45-minute, 60-minute, 90-minute, and 3-hour (180-minute).
What finish should I specify for commercial door hardware?
The most commonly specified commercial hardware finish is US26D (626), satin chromium, which provides a durable matte silver appearance. For environments with moisture or chemical exposure, US32D (630) satin stainless steel is preferred. The finish should be consistent across all hardware on each opening. CDF’s ProBuilder displays available finishes for each hardware selection during the configuration process.
