Parts of a Commercial Door – Storefront and Steel Door

All 19 parts on the diagram

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Start here: 7 main parts 7

Glass lite The glass in the door; lite is the trade word for it.
Header (head) The horizontal frame member across the top.
Jamb A vertical frame member: hinge jamb one side, strike jamb the other.
Threshold The strip across the floor under the closed door.
Pull handle (pull) The fixed handle on the outside of the door.
Door closer Closes the door at a set speed. A spring and oil device.
Exit device (panic bar) Pushing the bar draws back the latch.

The frame 4

Transom The framed area directly above the door opening.
Transom bar The horizontal frame member over the door, under the transom.
Sidelight A framed, fixed area of glass right beside the door.
Mullion The frame member between the door and the sidelight.

The door 4

Stile The vertical members at the door's two edges.
Top rail The horizontal member at the door's top.
Bottom rail The horizontal member at the bottom, taller than the top rail.
Glazing stop Holds the glass in the door. It comes off to change the glass.

Hardware 4

Mortise cylinder The round keyed cylinder set into the door's lock edge.
Offset pivot One at the top and one at the bottom carry the door.
Strike Fixed to the frame; receives and holds the latch.
Kick plate Shields the door from feet and carts.

How this list was compiled: Read 2026-09-30; a name is kept only where two of these use it. (1) A storefront door maker's guide specification for its standard aluminium entrances, linked from https://www.kawneer.com/products/doors-and-entrances/190-350-500-standard-entrances/ : narrow, medium and wide stile doors, top rail and taller bottom rail, glazing stops and gaskets, threshold, offset pivots, push/pull, exit device, closer, mortise cylinder and thumbturn. (2) Steel Door Institute, Hollow Metal Door Nomenclature, https://steeldoor.org/glossary/ : stile, rail (top, bottom), head or header, jamb (hinge jamb, strike jamb), mullion, transom, transom bar, sidelight, door light, glazing bead or stop, pivot hinge, strike, panic hardware and rim exit device, pull side and push side. (3) A second entrance maker's flush glazed framing and door installation instructions, https://special-lite.com/wp-content/uploads/2019/06/Flush-Glazed-Framing.pdf , and its monumental doors brochure: header, jamb, mullion, threshold, lite, glass stop, glazing bead, hinge stile, strikes, closers and pivots, stiles and top and bottom rails. (4) A hardware maker's guide, https://www.pdqlocks.com/blog/different-types-of-commercial-door-hardware : exit devices, door closers, kick plates. (5) Wikipedia: Transom (architecture) (the crosspiece between a door and a window above it), Crash bar (exit device, panic bar; pressing the bar unlatches the door), Door closer, Door furniture (pull handle, kickplate), Mortise lock (mortise cylinder). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's door, nothing traced. Licence: own work

How it works

A shop entrance is usually an aluminum frame with a glass door in it, so these are also the parts of a glass door. The second view is a steel back door from inside, with its closer and exit device.

Read the full guide

The frame

The header runs across the top and a jamb stands at each side. A mullion is an upright between two openings, here between the door and the sidelight. The transom bar is the crosspiece over the door, and the glass above it is the transom.

The door

The two stiles are the uprights, and the rails run across the top and bottom. The glass sits between them, held by the glazing stop. This door turns on offset pivots at the top and bottom in place of hinges, and closes onto a threshold.

On the steel door the exit device is on the inside: pushing the bar toward the way out draws back the latch.

Questions and answers

What are the parts of a commercial door called?

On a storefront door: header, jambs, transom, stiles, top and bottom rails, glass lite, glazing stop, pull, mortise cylinder, pivots and threshold. On a steel door: door closer, exit device, strike and kick plate.

What is the bar across a commercial door called?

An exit device, also called a panic bar or crash bar. Pushing it in the direction of the exit draws back the latch, so people can get out without turning a handle.

What is the window above a commercial door called?

A transom. The horizontal bar between the top of the door and that glass is the transom bar. A fixed pane of glass beside the door is a sidelight.

What is the difference between a stile and a rail?

Stiles are the vertical members at the two edges of a door. Rails are the horizontal members at the top and bottom. On a narrow stile door they are thin, so most of the door is glass.