The Doorman’s Glossary

Name: American Door
Address: 9 Lucon Drive, Deer Park, NY, 11729, US
Telephone: +1-888-226-3667

Plain-language definitions of the terms used for commercial doors, loading dock equipment, gates and fences, and garage doors. Terms are linked from our product pages, and we add new ones as we go.

A

Air Infiltration: The passage of air into or out of a building through cracks and gaps in its shell. Doors and windows are common sources of air leakage, and the energy loss that comes with it. For doors, air infiltration is usually given in cubic feet of air per minute per square foot of door (cfm/sq ft): the lower the number, the more airtight the door.
AnchorLoc: A guide rail option on Pentagon EntrexGuard and DefendaGuard rolling shutters that retains the ends of the curtain inside each guide rail, for extra strength and stability.
ASCE Wind Load: A wind load calculated with the method published by the American Society of Civil Engineers (ASCE 7), the standard used by U.S. building codes to estimate the wind pressure a structure, including its doors, must resist.
ASTM D1929: A standard test method for the ignition temperature of plastics. It reports the flash ignition temperature and the self-ignition temperature: the lowest air temperatures at which the material ignites with and without a pilot flame.
ASTM E84: A standard test method for the surface burning characteristics of building materials. It measures how far a flame spreads across the material and how much smoke it develops, reported as a Flame Spread Index and a Smoke-Developed Index. Class A is the best rating.
Astragal: A flexible seal, usually vinyl or rubber, along the bottom edge of a door (or where two door leaves meet) that closes the gap against the floor or the other leaf to keep out drafts, water, dust and pests.

B

Barrier Gate Operator: The motorized unit that raises and lowers a barrier gate arm. It is usually tied into an access control system so a card reader, keypad, loop detector, telephone entry or guard station can open it. See barrier gate arms.
Bi-Part: On sliding or folding grilles, a closure made of two curtains that meet in the middle of the opening, used for wide openings.
Bottom Bar: The bottom edge of a rolling or sectional door, which meets the floor when the door is closed. It often carries a rubber seal, and can hold a safety edge or other sensors. A sloping bottom bar is shaped to fit an uneven or sloped floor.
Brick Pattern: A rolling grille or shutter curtain pattern in which the openings are staggered like courses of brick.

C

Cable Failure Device: A safety device on a sectional overhead door that stops the door from falling if a lift cable breaks.
Cantilever Gate: A sliding gate that is supported on rollers mounted beside the opening, so it rolls back without a track across the driveway and without touching the ground in the opening. See cantilever sliding gates.
Caster: A small wheel mounted under a gate or other movable unit so it can be rolled. Scissor gates often run on steel casters.
Chain Link Mesh Gauge: The thickness of the wire woven into chain link fabric. The lower the gauge number, the thicker the wire: 9 gauge is heavier than 11 gauge. Mesh is also described by the size of its diamond openings, such as 2".
Counter Shutter: A small rolling shutter that closes a counter or service window opening, such as a cafeteria counter, concession stand or pharmacy window. Fire-rated counter shutters close automatically in a fire. See rolling counter shutters.
Counterbalance: The spring system that offsets the weight of a door so it can be opened by hand or by a motor with reasonable force. Most rolling and sectional doors use torsion springs.
cULus Listed Equipment: Equipment that UL (Underwriters Laboratories) has tested and certified to the applicable safety standards for both the United States and Canada. The "c" and "us" beside the UL mark stand for the two countries.
Curtain: The part of a rolling, coiling or folding door that moves to open and close the opening. A curtain can be made of interlocking slats, panels, fabric, PVC, rubber or a grille.
Cylinder Lock: A key-operated lock on a rolling or sectional door that locks the door to the guides or the floor, so it can be locked and unlocked from outside with a key.

D

Deflection Plate: A steel plate at the base of a guard rail post that spreads the load into the ground or floor when a vehicle hits the rail.
Dock Leveler: A hinged plate built into a loading dock that bridges the height difference and gap between the dock floor and a truck bed, so forklifts and pallet jacks can drive on and off. See dock levelers.
Dock Seal: Compressible foam pads mounted around a loading dock door that press against the back of a trailer to seal the gap and keep weather, conditioned air and pests from passing. See dock seals vs. dock shelters.
Drop Pin: A vertical pin on a gate that drops into a hole or sleeve in the floor to hold the gate closed.
Drop Stop Device: A safety device that keeps a door from falling if a component that holds it open, such as a spring or cable, fails.
Drop Test: A test in which a rolling fire door or fire shutter is released so it closes as it would in a fire, to confirm it closes fully and resets properly. NFPA 80 requires fire doors to be tested regularly. See rolling fire door drop testing.

E

Emergency Egress: A feature that lets people open a closed grille, door or gate from the inside to get out in an emergency, for example when the power is off.
Encapsulated Insulation: Insulation fully enclosed between a door section's skins, so it is protected and not exposed.
Endlocks: Metal or plastic pieces fixed to the ends of the slats in a rolling door curtain. They keep the slats from shifting sideways, which causes wear and jamming. Windlocks are a heavier type that also hold the curtain in the guides under wind pressure.

F

Fenestrated Slat: A rolling door slat with cut-out openings (also called a punched slat) that lets air and some light through while keeping the door secure. See punched metal slats.
Fire-Rated: Describes a door, shutter or other assembly tested and labeled to resist the passage of fire for a set time, such as 1 1/2 or 3 hours. Fire-rated rolling doors and shutters close automatically when a fire is detected, and must be tested periodically.
Fusible Link: A link made of two parts held together by an alloy that melts at a set temperature. In a fire the link separates and releases a rolling fire door or shutter so it closes.

G

Gate Operator: The motor and controls that open and close an automated gate. Operators are made for each type of gate: sliding, swing, vertical pivot or barrier arm.
Guide Rail: The vertical track on each side of an opening that holds the edges of a rolling door, shutter or screen curtain as it travels. Also called a guide.

H

Helical Torsion Spring: A coiled spring that stores energy by twisting. On overhead and rolling doors it is mounted on a shaft or in a barrel above the opening and offsets the weight of the door.
Hollow Metal Door: A steel personnel door made of two steel faces over an internal core or reinforcement, hung in a steel frame. Common in commercial buildings. See hollow metal doors.
Hood: The cover over the coil of a rolling door or shutter, protecting the coiled curtain and hardware. A hood baffle is a seal inside the hood that reduces air passing over the coil.

I

I-Beam Gate: A heavy-duty sliding gate that runs on a steel I-beam track, used for very large openings. See cantilever vs. I-beam gates.
Impact Door: A flexible swinging door, opened by pushing through it with a cart, pallet jack or forklift, that springs back closed. Used between areas of different temperature. See impact swinging doors.
Interlock: A switch that prevents a door's motor from running unless a condition is met: for example, that a manual lock is open or that a man door in the curtain is closed.

J

Jackshaft Operator: A door operator mounted on the wall beside the door that turns the door's torsion shaft directly, rather than pulling the door from a rail on the ceiling. Common on sectional doors.

K

Kalamein Door: A fire-rated personnel door with a solid wood core covered in galvanized steel. See Kalamein doors.

L

Lead Post: The post at the leading edge of a sliding grille curtain that locks into the wall, floor or ceiling to secure the closed grille.
Lites: Clear panels set into a door slat or section to let light in or allow people to see through the door. Also called vision lites.
Loop Detector: A wire loop buried in the pavement that senses a vehicle by the change in its magnetic field, and signals a gate or door operator to open, stay open or close. A safety loop keeps a gate from closing on a vehicle.
Low-E Glass: Glass with a thin, nearly invisible coating that reflects heat, improving the thermal efficiency of a glazed door.
Low-Temp PVC: A strip curtain PVC formula that stays flexible at very low temperatures, for freezers and cold rooms.

M

Magnetic Lock: An electromagnet on the frame and a steel plate on the door or gate that hold it shut while powered. Used with access control systems.
Mortise Lock: A lock set into a pocket (mortise) cut into the edge of a door, rather than mounted on its surface.
Mullion: A removable or fixed vertical post between two doors in a wide opening, or at a corner, that the doors close against.

N

NEMA Rating: A rating from the National Electrical Manufacturers Association for electrical enclosures, describing the conditions they withstand. For example, NEMA 4 is watertight and NEMA 4X is also corrosion resistant.
NFPA 80: The National Fire Protection Association standard for fire doors and other opening protectives. It covers their installation, inspection, testing and maintenance.

O

OITC (ASTM E1332): Outdoor-Indoor Transmission Class: a rating of how well a wall, door or window reduces outdoor transportation noise such as traffic, rail and aircraft. It weights lower frequencies more than STC does.
Openness Factor: The percentage of a screen or shade fabric that is open to light and air. A 0% fabric is opaque; a 5% fabric lets more light and view through.
Ornamental Gate: A decorative steel or aluminum gate, often with pickets and finials, used where appearance matters. See ornamental gates.

P

Panic Bar: A push bar across a door that unlatches it when pressed, so people can exit quickly without using a key or knob. Also called panic hardware or an exit device. A rim exit device latches on the surface of the door edge. See panic bar exit devices.
Pass Door: A personnel door built into a larger door so people can walk through without opening it. Also called a wicket door.
Perforated Slat: A rolling door slat punched with small round holes, so the closed door allows air flow and some visibility.
Perimeter Seals: Seals along the sides and top of a door opening that close the gap between the door and the building, improving insulation and reducing noise and drafts.
Picket Top: The decorative top of an ornamental fence or gate picket, such as a pressed spear or triad spear.
Post Cap: A cap fitted to the top of a fence post to finish it and keep water out.
Powder Coating: A finish applied as a dry powder that is electrically charged, sprayed onto the metal and cured with heat. It forms a thicker, more durable coating than conventional paint. See powder coating.
Privacy Slats: Vinyl or aluminum strips woven into chain link fence to block the view through it.

R

R-Value: A measure of a material's resistance to heat flow. The higher the R-value, the better it insulates. R-value and U-value are inverses: R = 1/U.
Razor Wire: Wire with sharp blades set along it, mounted on top of a fence to deter climbing. Barbed wire uses twisted barbs instead of blades.
Reversing Edge: A sensing strip along the bottom of a motorized door that detects contact with an object and makes the door stop and reverse.
Roll Housing: The box that encloses the coiled curtain of a rolling shutter or screen.

S

Scissor Gate: A folding security gate of crossing steel members that collapses to the side when open. See scissor gates.
Sectional Door: An overhead door made of horizontal panels hinged together that roll up on tracks to sit under the ceiling. See rolling steel vs. sectional doors.
SFIC Core: Small Format Interchangeable Core: a lock cylinder core that can be removed and replaced with a control key, so locks can be rekeyed quickly.
Shiplap Joint: A section joint in which the edges of adjoining door sections overlap, adding rigidity and helping keep out weather.
Slat: One of the interlocking formed strips that make up a rolling door curtain. Slats come in many profiles, gauges and materials, and can be insulated, perforated or powder coated.
Slat Profile: The cross-section shape of a slat, such as flat or single crown, often with its height (for example, a 3" single crown slat).
Slide Lock: A manual lock mounted on the inside of a rolling or sectional door that slides into a slot in the guide or track to hold the door closed.
Sloping Bottom Bar: A bottom bar shaped to follow a sloped or uneven floor, so the closed door seals across the full width.
Smoke Seal: A seal, usually a brush type, on a fire-rated door or shutter that limits the passage of smoke when it is closed.
STC Rating: Sound Transmission Class: a rating of how well a wall, door or window reduces airborne sound, especially speech. A higher number means better sound reduction.
Strike Plate: The metal plate on a door frame that the latch or bolt engages.
Strip Curtain: Overlapping flexible PVC strips hung in an opening. People and vehicles pass through while the strips limit air exchange, dust and pests. See vinyl strip curtains.
Swing Gate Operator: A motor that opens and closes a swinging gate, mounted on the gate post or under the gate.

T

Tempered Glass: Heat-treated safety glass that is stronger than ordinary glass and breaks into small pieces rather than sharp shards.
Terminal Section: The end piece of a guard rail run, such as an end shoe or flared end, that finishes the rail and anchors it.
Thermal Break: A material with low thermal conductivity placed between metal parts to reduce heat flow through an assembly, such as between the inside and outside skins of an insulated door section.
Track Lift: The way a sectional door's tracks are arranged: standard lift, high lift or vertical lift, depending on the headroom above the opening.
Trolley Operator: A door operator mounted on the ceiling that pulls the door open along a rail, with a chain, belt or screw drive.

U

U-Value: A measure of how much heat passes through a material or assembly. The lower the U-value (or U-factor), the better it insulates.
UL 325: The UL safety standard for door, drapery, gate, louver and window operators. Automatic gate and door operators are tested and listed to it.
UL Listed: Tested and certified by UL (Underwriters Laboratories) to the applicable safety standard. Fire-rated doors carry a UL label showing their rating and class.

V

Variable Frequency Drive: A motor controller that varies the frequency and voltage of a motor's power supply to control its speed. On high speed doors it gives a soft start and stop, reducing wear.
Vertical Pivot Gate: A gate that pivots upward from one end to open, used where there is no room for a sliding or swing gate. See vertical pivot gates.

W

W-Beam: The common corrugated steel guard rail profile, shaped like a W in cross-section.
Wicket Door: A personnel door built into a larger door, gate or fence, so people can pass without opening the large door. Also called a man door or pass door. See roll up door man doors.
Wind Bar: A horizontal reinforcing bar in a fabric curtain or screen that helps it resist wind.
Wind Load: The force wind applies to a door, given as pressure in pounds per square foot (PSF). A door's wind load rating is the pressure it is designed to withstand.
Windlock: A heavy endlock that keeps a rolling door's curtain engaged in the guides under strong wind pressure. Roller windlocks let the door keep operating in moderate winds.
Wool Pile Inserts: Brush-like strips in the guides of a rolling grille that reduce rattling and noise as the curtain moves.

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