Garage door glossary

The barrel is the cylindrical shaft inside a roller door's headbox that the curtain winds around as the door is raised and lowered.

Canopy gear is a UK up-and-over garage door mechanism where the springs and pivot arms sit entirely on the head of the frame above the opening, so roughly a third of the door remains outside the garage when open.

The curtain is the complete assembly of interlocking slats that forms the moving surface of a UK roller garage door, winding onto the barrel as the door opens.

Drive-through width is the clear, unobstructed horizontal space available once a garage door is fully open, measured between the finished sides of the opening.

An extension spring is a coiled spring mounted along each side track that stretches to store energy as the door closes, most often used on retractable-gear up-and-over doors.

The fixing frame is the perimeter frame fitted into the structural opening that the garage door, its tracks and its hinges or gear are actually mounted to.

Force limitation is the requirement under BS EN 12453 that a power-operated garage door detect resistance from an obstruction and stop or reverse rather than continuing to close with excessive force.

Headroom is the vertical clearance above the top of a garage door opening, needed to house the door's track, springs or, on a roller door, the headbox.

A lifting cable is a steel wire rope that connects the bottom corners of a garage door to the spring or drum mechanism, helping guide and support the door as it opens and closes.

The operator is the electric motor unit that drives a garage door open and closed automatically, typically controlled by a remote handset, keypad or smartphone app.

A photocell is a paired safety sensor, one transmitter and one receiver, mounted on each side of a UK power-operated garage door that stops the door closing if the infrared beam between them is broken.

Retractable gear is a UK up-and-over garage door mechanism with springs mounted on both sides of the frame, letting the whole door retract fully inside the garage and handle openings up to around 5m wide.

A roller door is made of narrow interlocking aluminium slats that wind onto a barrel housed in a headbox above the opening as the door is raised.

A round-the-corner door is an up-and-over variant whose track curves at the top of the opening to run back along the garage side wall instead of straight along the ceiling, used where roof space is limited.

A sectional door is made of several hinged horizontal panels that travel vertically up into the roof space along a track, rather than pivoting outward as a single panel.

Side room is the clear space to the left and right of a garage door opening, needed for the door's side tracks, retractable-gear springs or fixing frame to be fitted.

A side-hinged door consists of two door leaves hung on hinges at each side of the opening that swing outward like a pair of traditional cottage doors.

A slat is one of the narrow, interlocking horizontal aluminium sections that together form the curtain of a roller garage door.

A spring cone is the fitting at the end of a torsion spring that anchors it to the shaft or frame and allows the spring's winding tension to be adjusted.

The structural opening is the raw masonry or timber opening in the garage wall before any door frame is fitted, measured wall to wall and floor to lintel.

A torsion spring is a coiled spring mounted horizontally above the door opening that twists to store energy as the door closes, releasing it to help lift the door when opened.

The track is the metal channel, either vertical, curved or horizontal, that guides a garage door's rollers or panels along their path as the door opens and closes.

A tubular motor is a cylindrical electric operator that fits inside the roller door barrel itself, driving the curtain directly rather than via an external gearbox and drive arm.

An up-and-over door is a single rigid panel that pivots outward and up on canopy or retractable gear to sit horizontally under the garage ceiling when open.

A wicket door is a small pedestrian access door built directly into a larger garage door panel, letting someone walk through without raising the whole door.