Garage Door Glossary

Aluminum Garage Door

An aluminum garage door is a sectional door whose sections are made from extruded aluminum rails and stiles, usually filled with glass, plastic or aluminum panels, giving a light door that does not rust.

Astragal: see Bottom Seal

Automatic Reversal System

An automatic reversal system is the safety feature built into a garage door opener that senses when the closing door hits an obstruction and drives it back up, as federal law requires within 2 seconds of contact.

Backroom

Garage door backroom is the horizontal depth measured from the door’s mounting surface back into the garage to the first obstruction, which the open door, tracks and opener must fit inside.

Balance Test

A garage door balance test is a check of whether the springs are carrying the door’s weight, done by disconnecting the opener and seeing whether the door lifts easily by hand and stays where it is left.

Belt-Drive Opener

A belt-drive opener is a garage door opener that uses a steel-reinforced rubber belt, instead of a metal chain, to pull the trolley that moves the door along a ceiling rail.

Bottom Seal

A bottom seal is the compressible strip of rubber, vinyl or silicone attached to the bottom edge of a garage door so that it squashes against the floor when the door closes, blocking water, drafts, debris and pests.

Cable Drum

A cable drum is the grooved wheel fixed to each end of a garage door’s torsion shaft that winds the lift cable on as the door opens and pays it out as the door closes.

Carriage House Garage Door

A carriage house garage door is a door styled to look like the side-hinged doors of old carriage houses, with wide panels, decorative handles and hinges, while usually opening straight up as a sectional door.

Center Bearing Bracket: see Torsion Shaft

Chain-Drive Opener

A chain-drive opener is a garage door opener whose motor turns a sprocket that moves a metal chain along a ceiling rail, and the chain pulls a trolley connected to the top of the door.

Commercial Sectional Door

A commercial sectional door is a vertically acting door made of hinged horizontal sections that rides on rollers in track, built heavier than a residential door for vehicle entrances at commercial and industrial buildings.

Corrosion Resistance

Corrosion resistance is the ability of a garage door’s panels, springs, cables, track and hardware to resist rust and chemical attack from moisture, salt and other contaminants, through material choice and protective coatings.

Counter Shutter

A counter shutter is a small rolling door that closes onto a counter-type sill, used to secure openings whose main purpose is non-pedestrian service, such as food counters, pharmacy windows and package transfer points.

Counterbalance System

A garage door counterbalance system is the set of springs or weights, with their cables, drums or pulleys, that offsets the door’s weight so a person or opener can move it with little force.

DASMA Technical Data Sheets

DASMA Technical Data Sheets are numbered technical guides published by the Door & Access Systems Manufacturers Association that explain industry terms, test standards, safety practices and code issues for garage doors, rolling doors, high performance doors and door operators.

Direct-Drive Opener

A direct-drive opener is a garage door opener whose motor rides inside the trolley and pulls itself along a fixed chain in the rail, so the motor and door connection move together.

End Bearing Plate: see Torsion Shaft

Entrapment Protection

Garage door entrapment protection is the set of required safety features on an automatic opener that make a closing door reverse when it meets a person or object, so no one is pinned underneath.

Extension Spring System

An extension spring system is a way of lifting a garage door with two long springs that stretch along the horizontal tracks when the door closes and pull back as it opens, through cables and pulleys.

Fiberglass Garage Door

A fiberglass garage door is a sectional door whose exterior face is molded fiberglass, usually textured to look like wood grain, bonded over a steel section that is often insulated with foam.

Fire-Rated Rolling Door

A fire-rated rolling door is a rolling steel door assembly with an automatic-releasing device that is tested and listed to protect an opening in a fire-rated wall, closing on its own when a fusible link melts or a detector or alarm signals.

Flush Panel Garage Door

A flush panel garage door is a door whose sections present a smooth, even face with no visible rails, stiles or raised panels, giving a flat, modern look.

Force Setting

The force setting is the opener control that sets how much push or pull the motor may use before it decides the door has hit something and reverses or stops.

Galvanized Steel Garage Door

A galvanized steel garage door is a door whose sections are made from sheet steel coated with zinc to protect it against corrosion, usually primed and given a baked-on paint finish on top of the zinc.

Garage Door Header

A garage door header is the horizontal framing member across the top of a garage door opening that carries the wall or roof above and provides the mounting surface for the spring assembly and opener bracket.

Garage Door Jamb

A garage door jamb is the upright framing member on each side of the door opening, to which the vertical tracks, brackets and side weatherstrip are fastened.

Garage Door Lubrication

Garage door lubrication is the routine application of a light lubricant to a door’s moving metal parts, such as hinge pins, roller bearings, torsion springs and bearings, to cut friction, noise and wear.

Garage Door Rough Opening

A garage door rough opening is the framed hole in the wall that the door closes, measured as opening width between the jambs and opening height from the floor to the bottom of the header.

Garage Door Spring Cycle Life

Garage door spring cycle life is the number of full open-and-close cycles a spring is rated to complete before metal fatigue is expected to break it.

Garage Door System

A garage door system is the complete working assembly of a garage door: the door sections, tracks and rollers, the spring counterbalance with its cables and drums, and, if fitted, the opener and its safety devices.

Headroom

Garage door headroom is the clear vertical space between the top of the door opening and the lowest obstruction above it, such as a ceiling, beam, pipe or light.

High-Lift Track

High-lift track is garage door track with extended vertical sections that make the door rise straight up some distance above the opening before it curves back into the horizontal track.

High-Speed Roll-Up Door

A high-speed roll-up door is a non-swinging, power-operated industrial door with an automatic closing device that opens at least 32 inches per second and closes at least 24 inches per second, used on busy vehicle and material-handling openings.

Hinge Numbering

Hinge numbering is the system of stamping garage door end hinges #1, #2, #3 and up, each one taller than the last, so that from the bottom of the door upward each roller sits a little further from the section and the door closes snugly against the jambs.

Horizontal Track

The horizontal track is the section of garage door track that runs back under the ceiling from the curved radius, guiding the door’s rollers and holding the door when it is open.

Impact Resistance

Impact resistance is a garage door’s tested ability to survive strikes from wind-borne debris, such as a flying 2x4, and then hold up under repeated wind pressure cycles without opening up.

Lift Cable

A garage door lift cable is the braided steel wire rope that connects the door’s bottom corners to the spring system, carrying the springs’ lifting force to the door as it opens and closes.

Loading Dock Door

A loading dock door is a door serving a loading dock, giving access to a parked transport vehicle so goods can be loaded and unloaded, usually as part of a system with a dock leveler, seals or shelter, bumpers and vehicle restraints.

Manual Release Mechanism

The manual release mechanism is the red handle on a cord hanging from a garage door opener’s rail that disconnects the door from the opener so the door can be raised or lowered by hand.

One-Piece Garage Door

A one-piece garage door is a door made of a single rigid panel that pivots from upright to a horizontal position above the garage floor when it opens, instead of bending through tracks in sections.

Opener Drive System

An opener drive system is the mechanism that carries a garage door opener’s motor power to the door, such as a chain, belt or screw pulling a trolley along a rail, or a wall-mount unit turning the door’s torsion shaft.

Opener Duty Cycle

An opener duty cycle is the number of door cycles an opener is designed to perform in a defined time period, which tells you how hard it can be used before its motor needs to rest.

Opener Horsepower

Opener horsepower is the lift-power rating printed on a garage door opener, and on most modern DC openers it is a comparison to an AC motor’s horsepower rather than a measured output.

Opener Rail Assembly

An opener rail assembly is the straight track on the garage ceiling that runs from the opener’s motor to a bracket above the door, carrying the trolley and the drive (chain, belt or screw) that moves the door.

Opener Travel Limits

Opener travel limits are the stored stopping points that tell a garage door opener where the door is fully open and fully closed, so the motor stops in the right place on every cycle.

Opening Height: see Garage Door Rough Opening

Opening Width: see Garage Door Rough Opening

Operating Noise

Operating noise is the sound a garage door system makes while it opens and closes, coming from rollers, hinges, springs, tracks, loose hardware and the opener, and carried into the house as vibration.

Panel Delamination

Panel delamination is the separation of a garage door section’s bonded layers, such as a steel, fiberglass or wood skin pulling away from its foam core or backing, which weakens the section and lets water in.

Panel Thickness

Panel thickness is the overall depth of a garage door section from its outer face to its inner face, which sets how much insulation the section can hold and how stiff it is, and is different from the gauge of the steel skin.

Perimeter Seal: see Weatherstripping

Photoelectric Safety Sensors

Photoelectric safety sensors are the pair of small units mounted near the floor on each side of a garage door that send an invisible light beam across the opening and make a closing door reverse if anything breaks it.

Pinch-Resistant Design: see Section Joint

Polystyrene Insulation

Polystyrene insulation, in a garage door, is rigid foam board, expanded (EPS) or extruded (XPS), that is cut to fit inside a door section and either inserted behind the steel skin or bonded between two skins.

Polyurethane Insulation

Polyurethane insulation, in a garage door, is a foam that makers inject between a door section’s two steel skins, where it expands to fill the cavity and bonds to the skins, insulating and stiffening the section.

Pressure Rating: see Wind Load

Preventive Maintenance

Preventive maintenance is the routine inspection, testing, cleaning and lubrication of a garage door and opener on a schedule, so that wear is caught early and the door stays balanced, safe and reliable.

Product Approval

Product approval is an official finding that a specific garage door model, as tested and installed per its drawing, complies with the building code, recorded under a number such as a Florida FL# or a Miami-Dade NOA.

R-Value

R-value on a garage door is a calculated measure of how well one door section resists heat flow, based on its insulation type and thickness; the higher the number, the slower heat passes through that section.

Raised Panel Garage Door

A raised panel garage door is a door whose sections show rectangular panels that stand out from the surrounding surface, in short or long shapes, giving the classic traditional garage door look.

Roll-Up Garage Door

A roll-up garage door is a vertically operating door whose curtain of interlocking slats or corrugated sheet coils around a barrel or axle above the opening when it opens, instead of sliding back under the ceiling.

Roller Stem: see Roller Wear

Roller Wear

Roller wear is the gradual breakdown of a garage door’s track rollers, the wheel-and-stem assemblies that guide each section along the track, through worn bearings, flattened or cracked wheels and bent or worn stems.

Rolling Code Technology

Rolling code technology is a remote-control security method in which a garage door opener and its remote change the transmitted code with every press, so a signal recorded once cannot be replayed to open the door.

Rolling Steel Door: see Roll-Up Garage Door

Safety Containment Cable

A safety containment cable is a steel cable threaded through the center of a garage door extension spring and anchored at both ends, so that if the spring breaks, its pieces stay on the cable instead of flying.

Sandwich Construction

Sandwich construction is a way of building a garage door section in which an insulating foam core is bonded between an exterior and an interior skin, so the three layers act together as one stiff, insulated panel.

Screw-Drive Opener

A screw-drive opener is a garage door opener in which a long threaded steel rod turns inside the rail and drives the trolley along it, pushing the door closed or pulling it open.

Section Joint

A section joint is the interface where the bottom meeting rail of one garage door section meets the top meeting rail of the next, shaped so the two edges nest together and form a weather-resistant seal when the door is closed.

Sectional Garage Door

A sectional garage door is a door made of two or more horizontal sections hinged together that ride on rollers in side tracks, bending through a curve to rest flat under the ceiling when open.

Service Life

Service life is the length of time, or number of open-close cycles, that a garage door system keeps operating safely before a component wears out and must be replaced, with the door, springs and opener each wearing at their own rate.

Sideroom

Garage door sideroom is the horizontal space from each side of the door opening out to the nearest wall or obstruction, where the vertical track and its brackets mount.

Sound Transmission

Sound transmission, for a garage door, is the amount of airborne noise that passes through the closed door from one side to the other, rated by single numbers such as STC and OITC that rise as noise reduction improves.

Spring Fatigue: see Garage Door Spring Cycle Life

Spring Inside Diameter: see Spring Wire Size

Spring Torque

Spring torque is the twisting force a wound torsion spring applies to the door’s shaft, measured in inch-pounds, which the cable drums turn into the lifting pull that balances the door.

Spring Wind Direction

Spring wind direction is the direction a torsion spring’s coils spiral, left or right, which decides which side of the center bracket the spring mounts on and which way it must be wound.

Spring Wire Size

Spring wire size is the diameter of the steel wire a garage door spring is wound from, written in thousandths of an inch, such as .250; thicker wire makes a stronger, longer-lasting spring for the same door.

Thermal Bridging

Thermal bridging is heat flow that bypasses a garage door’s insulation through more conductive paths, such as steel that wraps from the outer to the inner skin at section joints and ends, stiles, hardware and gaps in the seals.

Threshold Seal

A threshold seal is a raised strip of rubber or vinyl, sometimes on an aluminum track, fixed to the garage floor where the door closes, so the door’s bottom seal lands against it and water, debris and pests are held back.

Torsion Shaft

A torsion shaft is the steel bar or tube mounted above a garage door that carries the torque from the torsion springs to the cable drums at its ends, which wind the lift cables.

Torsion Spring System

A torsion spring system is the set of springs, shaft, drums and cables mounted above a garage door that twists to store energy and lifts the door’s weight when it opens.

Torsion Spring Wire Diameter: see Spring Wire Size

Track Lift Type

Track lift type is the shape of the track a sectional garage door rides in, which sets the path the door takes as it opens: turning back under the ceiling early, late, or not at all.

Track Misalignment

Track misalignment is a fault in which a garage door’s vertical or horizontal tracks are bent, loose, out of plumb or not parallel, so the rollers bind, grind or leave the track instead of running freely.

Track Radius

Track radius is the radius of the curved section of garage door track that joins the vertical track beside the opening to the horizontal track under the ceiling, commonly 12 or 15 inches on homes.

Travel Distance: see Opener Travel Limits

U-Factor

A garage door U-factor is the measured rate of heat flow through a complete installed door, including sections, joints, hardware and seals, tested under ANSI/DASMA 105; the lower the U-factor, the less heat the door lets through.

UL 325 Safety Standard

The UL 325 safety standard is UL’s rulebook for door, drapery, gate, louver and window operators, and its entrapment rules for garage door openers are part of U.S.

Vertical Track

The vertical track is the upright section of garage door track fastened beside each side of the opening, which guides the door’s rollers from the floor up to the curved radius section.

Vertical-Lift Commercial Door: see Commercial Sectional Door

Vertical-Lift Track: see Track Lift Type

Vibration: see Operating Noise

Vision Panel

A vision panel is a cutout in a garage or commercial door that is glazed with clear glass or plastic, so people can see through the door and daylight can enter while it is closed.

Weatherstripping

Weatherstripping is the set of flexible seals that close the gaps around a garage door, chiefly the perimeter seal along the jambs and header, plus seals at the top, between sections and at the bottom edge.

Wind Load

Garage door wind load is the pressure wind puts on a closed door, pushing it in and pulling it out, measured in pounds per square foot (psf) and set for each building by the local code.

Wind-Bracing System

A garage door wind-bracing system is the set of horizontal struts, and sometimes vertical posts, that stiffen a door so it resists wind pressure without bending out of its tracks.

Wind-Load Rating: see Wind Load

Wind-Rated Assembly: see Wind Load