Parts of a Door: Learn About the Anatomy of a Door (2023)



Are you shopping for a new door, or is there a door in your home that needs repairing? You could benefit from this door parts glossary.

July 13, 2022

If you’re embarking on a door replacement or new build project and you’re overwhelmed with all the technical terms, we’ve got you covered. This post breaks down all the parts of a door so you can understand the terminology and how all the parts and pieces come together. Understanding the basic parts of a door makes it easier to talk with contractors and dealers to choose the right door for your project.

Door frame

Side jambs, head jambs, and mulls are the parts that make up the frame. Residential door frames are most often made of woodbut can also be made of aluminum, fiberglass, or a composite material. Door frames can be purchased primed (ready to paint) or ordered with a factory finish in a variety of colors.

Head jamb

The top horizontal section of a door or window frame is called the head jamb.

Door jamb versus door frame

A door jamb is an individual section of a door frame. Two side jambs make up the vertical components of the door frame and the head jamb is the top horizontal component. Together, the jambs (along with mullion) comprise the door frame.

Mullion (mull)

When two individual windows or a door and window are joined, the seam between the frames of the two units is called the mull, which is short for mullion. In this case, a door jamb has been joined to a window/sidelight jamb. The seam is typically hidden with a piece of trim called a mull casing (See additional definition below).

Parts of a Door: Learn About the Anatomy of a Door (1)Figure 1. Shows Door Parts including: Head Jamb, Side Jamb, Casing, Mullion (Mull), Threshold, Sidelight and Glazing.


Sills are the bottom component of a door frame. They are the part of the door that gets sealed and fastened to the floor. Only exterior doors (those that lead to the outdoorsor garages) have sills. Learn how to prep a floor for a door sill.

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A threshold is the protective cap that covers the sill. It is typically sloped toward the outside to help shed water. Thresholds are made of durable materials like metal or fiberglass because they need to be strong enough to withstand foot traffic.


Glazing is just another word for the glass in a door or window. The glazing in newer exterior doors like this one are made up of at least two layers of glass and sometimes three. Inert gas, usually argon, is injected between the glass layers to provide additional insulation. Nearly invisible coatings are added to glass to help manage the amount of light and heat conducted through a windowpane or reflected away from it. Glazing can be enhanced with tints and laminations in order to add privacy, provide decorative options, and increase strength. Find out more about glazing.


Sidelights are tall narrow windows found on one or both sides of a door. Sidelights allow more light into entryways, improve views, and can create a more welcoming entry point experience. Find out more about sidelights and when you might want to install one.


Window and door casingtrim is designed to hide the gaps between a window or door frame and the surface of the interior wall.

Parts of a Door: Learn About the Anatomy of a Door (2)Figure 2. Shows Brick Mould and Weather Stripping

Brick mould

Brick mould is an exterior casing trim designed to conceal the gap between a window or door frame and the exterior wall surface. Brick mould is thicker than most interior casing trim profiles and provides a buffer between the window/door and the brick or other cladding surrounding it. Brick mouldcan be made of wood, aluminum, PVC, fiberglass, or composite materials and is the part of the door that a screen door or storm door is attached to.


On exterior doors, weather-stripping helps seal the gaps between a door frame and a closed-door panel, weather-stripping is typically made of a resilient, flexible material like silicone, rubber, or foam.


Door sweep

The weather-stripping installed on the bottom of a door panel, a door sweep creates a weather resistant barrier between a door panel and sill.


On an exterior double door arrangement like the one above, an astragal covers the seam between the two door panels and is fitted with weather-stripping to prevent wind and water from entering the house.


A transom is a narrow window located above a door or window. Most transom windows do not operate, but if they do, they are typically hinged at the top like an awning window.Simulated divided lite bars (SDL)Because large panes of glass are now stronger, less expensive to manufacture, and more energy efficient, muntin bars have largely been replaced with SDL Barswhich rest on the surface of the glass.



Grilles are bars that create the effect of divided lites but are removable for easy glass cleaning. Grilles-Between-the-Glass (GBG) are also available. As the name suggests, GBGs are bars that are permanently installed between the glass panes for easy cleaning and low maintenance.

Muntin bars

Up to the middle of the 19th century, large panes of glass were fragile and expensive to create, muntin bars were joined together in order to create large expanses of glass from smaller individual panes (Not shown).

Parts of a Door: Learn About the Anatomy of a Door (3)Figure 3. Shows Transom, SDL Bars and Astragal

Parts of a Door: Learn About the Anatomy of a Door (4)Figure 4. Shows Top Rail, Panel, Lock Stile, Bore Hole, Mullion, Bottom Rail, Stop Moulding, Hinge Style, Mid Rail, Hinge

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A door panel, sometimes called a slab, refers to the whole part of the door that swings back and forth. Full door panels are often divided up into smaller panels, which are set between the stiles, rails, and mullions.


The narrow horizontal segments on a door panel are called rails. This door has a top, bottom, and a mid-rail.


A stile is the narrow vertical segment located on either side of a door panel. One is called the lock stile and the other a hinge stile.


A mullion resembles a stile. It is the vertical component that separates two panels located in the middle of the door between the rails.

Stop moulding

Door stop moulding is attached to a door frame. It aligns the door panel within the frame and prevents the panel from swinging right through the opening.


This is the piece of hardware that allows the door to swing open and closed. Standard sized doors have three hinges, but larger doors will have four or more. The color or finish of the hinges typically matches the finish of the lockset.

Bore hole

A bore hole is drilled into a door to accommodate a lockset.


The lockset refers to the handles, locks, latches, strike plates, and all the other hardware components that allow a door to latch and lock in place. Locksets are also referred to as handlesets or hardware.


A handle, knob, or lever is the component of door hardware that is used to unlatch the door panel and pull it open or push it closed. There are many styles and finishes to choose from. There are three types of door handles:

Entry handles

are operated with a key cylinder on the exterior side of the door and a push or turn lock button on the interior.

Bed/bath handles

have a push or turn lock button on the inside but not on the other.

Passage handles

have no locking mechanism.


A door latch is a shaft that protrudes from the edge of a door panel and into the door frame securing the panel in place. When the handle is turned, the latch retracts allowing the door to be opened.


Similar to a latch, a deadbolt is a shaft that protrudes from the edge of the door panel and into the door frame securing the panel in place. Residential interior doors are not equipped with deadbolts, and not all exterior doors have them either. Deadbolts are considered an additional form of security and are most often set apart from the handle assembly, which means that a door with a deadbolt needs an additional bore hole. Multi-point locking hardware systems provide even more protection than a latch and deadbolt combination, and new home automationsystems are available.

Thumb turn

A deadbolt is operated by turning a thumb turn on the inside of a house and by a key cylinder on the exterior side.

Mortise plates

These plates add strength to latches, deadbolts, and the door panel, which helps prevent a forced entry.

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Strike plates

Strike plates add strength to door frames which helps prevent a forced entry.


Escutcheons are ornamental plates that can be found surrounding handles, thumb turns and key cylinders. They’re designed to protect the surface of the door panels from nicks and scratches.

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What is the most important part of a door? ›

Hinges: Hinges are quite an important part of a door. It secures the door to the frame. Also, it enables a swinging motion.

What are the three parts of a door? ›

The body of any door is essentially made of three main parts: the stiles, rails and panels but there are many more elements. To help explain the most common terminology, here we have put together an illustration of a standard door and door frame, with the component parts highlighted.

What is the part around a door called? ›

The frame (sometimes called a jamb) is made up of three separate pieces and surrounds the door creating a "frame" in which the door can sit. The two vertical frames are called side jambs, and the horizontal frame is referred to as the head jamb. Frames are made up of composite material or solid wood.

What are the parts of door hardware called? ›

A: The five main types of door hardware include doorknobs, lever handles, deadbolts, handlesets, and door hinges.

What is the gap between door and frame called? ›

Margins (sometimes also called “rebates”) are the spaces between the door and the door frame. These are often important if you're looking at issues with your hinge jamb. Again, these spaces can be broken down into specific types: the hinge margin, strike margin, top (header) margin, and bottom (sweep) margin.

What is the structure of the door? ›

Shows Door Parts including: Head Jamb, Side Jamb, Casing, Mullion (Mull), Threshold, Sidelight and Glazing.

What are the features of a door? ›

A door is a hinged or otherwise movable barrier that allows ingress (entry) into and egress (exit) from an enclosure. The created opening in the wall is a doorway or portal. A door's essential and primary purpose is to provide security by controlling access to the doorway (portal).

What is the weakest part of a door? ›

What are the 3 weakest points of a door? A door is usually most vulnerable at its strike plate, its hinges, and its existing lock hardware. Burglars and criminals are prone to attacking these points because that's where it's easiest to get in.

What is a 3 point door? ›

Whereas in single-point locking, the door on a cabinet locks only at the point where the key is turned, halfway up the edge of the door, three-point locking enables the top and bottom of the door to be simultaneously secured.

What is a two part door called? ›

Double Acting Door: A door that can be opened from either side, pushing or pulling. It is sometimes called a double-sided door or a Dutch door.

What is a hole in a door called? ›

A peephole is a small hole in a door or wall through which you can look secretly at what is happening on the other side.

What is the little hole in a door called? ›

A peephole, peekhole, spyhole, doorhole, magic eye, magic mirror or door viewer, is a small, round opening through a door from which a viewer on the inside of a dwelling may "peek" to see directly outside the door.

What are the parts of a door hinge called? ›

Most hinges consist of three basic parts: leafs, a knuckle and a pin. Leafs are the rectangular-shaped plates on the sides of a hinge. A knuckle is a cyldrical-shaped tube that's created when the leafs are joined together. A pin is a solid metal rod that's inserted through the knuckle to interlock the leafs.

What holds a door in place? ›

Latch. The latch is the part that holds the door closed. When you turn the doorknob or push the handle down, the mechanism causes the latch to be pulled into the door, allowing the door to open.

What is a door mechanism called? ›

A latch mechanism is the cylinder that is driven through the edge of the door. This is often also called a tubular latch mechanism. The mechanism has a spring loaded latch that retracts to open the door and upon release of the door knob or lever, protrudes to keep the door closed.

What is the internal part of a door handle called? ›

It is called a backplate, as this is the plate behind the lever or the knob. A backplate is also known as a rosette or rose if it is circular in shape.

What is a door mullion? ›

Mullions are the dividing bars that separate glass panes in a door, much like those found in window panes. For many years, mullioned glass cabinet doors were the most popular choice among homeowners, mostly because there weren't that many styles of glass-front cabinet doors available.

What is door shape called? ›

A shape which has 6 rectangular faces, 8 vertices and 12 edges is called Cuboid and from the definition of Cuboid we can get the shape of a door will be Cuboidal because the door has also 6 rectangular faces, 8 vertices and 12 edges.

Is a door part of a structure? ›

All buildings have similar components such as foundation, plinth, walls, floors, doors, windows and roof. Every component has its own function. Non-structural components are parapet walls, door and windows, furnishings fixtures, partitions or partition walls, tiles, paint etc.

How do u define a door? ›

: a usually swinging or sliding barrier by which an entry is closed and opened. also : a similar part of a piece of furniture. : doorway. 3. : a means of access or participation : opportunity.

What are the two types of doors? ›

Types of Doors for Interiors. The single-hinged door is the most common interior type of door. Room design must allow space for hinged doors to swing. Interior doors typically are lightweight and have two hinges; exterior doors are heavy and often use three hinges.

Which door is the strongest? ›

Steel. A steel door is considered to be the strongest type of door. However, only by a small margin over wood and fiberglass. Steel doors are by far the least expensive entry door on the market.

What makes a door strong? ›

STEP 1: Replace your door with a sturdier one.

Your existing one will be too easy to kick in regardless of how strong the lock is. The strongest doors are generally solid wood or steel, but there are some very sturdy fiberglass doors, some with wood cores, that offer a little more style.

What is the core of a door? ›

Solid core doors are made of a mixture of wood and synthetic wood composites. They have a heavy, solid interior and a wood veneer exterior. They provide the durability, sound insulation, and look of a solid wood door without the weight or hefty price tag.

What is a 5 point lock? ›

A 5 lever mortice deadlock is commonly fitted to wooden doors and is locked from both the inside and outside with a key, they are fitted within the material of the door, rather than on the surface. Any five-lever mortice deadlock that is NOT BS3621 approved will usually have a Nightlatch fitted as additional security.

What is a striker in a door? ›

Striker Plate

A strike plate is a piece of hardware that works with a lock to keep a door secure. Strike plates are installed on the door frame and contains a hole which receives the spring loaded latch or bolt which comes out of the latch or lock.

What is a two point lock? ›

These 2 Point handlesets work basically just like a simple deadbolt and entrance lock. The deadbolt is locked straight into the door jamb and secures the door in place, and the cylinder below locks the handle or lever keeping it in place. Basically, the 2 Point locks are a step up from the regular handleset.

What is a door sash? ›

A sash door is a door that is partly constructed of glass and the door sash refers to the glass part of that door. The sash may include a single pane of glass or a collection of smaller panels.

What is a door casing? ›

Interior door casing is the term used to describe the trim found around a door opening. According to This Old House, “Door casings are both decorative and utilitarian, enhancing the look of the door while also concealing the transition between the wall and the jamb.”

What is a door latch plate? ›

A metal plate on the edge of the door, next to the latch or deadbolt, the faceplate protects the lock from wear and tear. It may have rounded corners or be a circular drive-in faceplate. The shape of the faceplate used during installation depends on your door's preparation.

What are the five components of windows? ›

  • 1 Configuration and maintenance.
  • 2 User interface.
  • 3 Applications and utilities.
  • 4 Windows Server components.
  • 5 File systems.
  • 6 Core components.
  • 7 Services.
  • 8 DirectX.

What are the main components of a window? ›

An application window includes elements such as a title bar, a menu bar, the window menu (formerly known as the system menu), the minimize button, the maximize button, the restore button, the close button, a sizing border, a client area, a horizontal scroll bar, and a vertical scroll bar.

What is window and door components? ›

Window sashes, frames, posts, skirtings and more. Door frames jambs, posts, stiles, rails, thresholds and more. Mouldings. Panelling.

What are the five elements of windows? ›

Elements of a window
  • Title Bar.
  • Menu Bar.
  • The Workspace.
  • Scroll bars -
  • Corners and borders.
26 May 2018

Where is the menu bar on the computer? ›

The menu bar is the part of a browser or application window, typically at the top left side, that houses drop-down menus that allow the user to interact with the content or application in various ways.

How the components of a computer system interact to perform a calculation? ›

It consists of two critical components, the control unit and the arithmetic logic unit (ALU). The control unit extracts information from a storage device, like the RAM, and executes the code contained within the data. The processor uses the ALU to perform mathematical calculations and parse logical operations.

What are the four parts of a window? ›

What Are the Parts of Windows?
  • Sill – The lowest part of the window frame.
  • Head – The highest part of the window frame.
  • Jamb – The vertical sides of the window frame.
  • Apron – A piece of decorative trim installed beneath the railing or sill.

What is the opening part of a window called? ›

The horizontal bar across the very top of the window frame. Top Rail – The name of the horizontal bar across the top of the casement. Bottom Rail – The larger horizontal bar across the bottom of the casement. Casement - The casement is the part of the window that opens, in which the glass sits.

What's the bottom of a door called? ›

A door sill, or threshold is what the bottom of a door frame is called; the horizontal part of the door frame that sits below the door.

What is the hole in the door frame called? ›

Bore holes are the holes in the door that house your door hardware and allow it to be installed. The cross bore is the main hole drilled into the face of the door where the body of the lock (chassis) is installed.

Where is the task bar on my laptop? ›

Typically, the taskbar is at the bottom of the desktop, but you can also move it to either side or the top of the desktop.

How do I add another desktop in Windows 10? ›

Create multiple desktops

On the taskbar, select the Task view icon, then select New desktop. Open the apps you want to use on that desktop. To switch to another desktop, select Task view again.

What is a desktop class 4? ›

Desktop is the main background screen of a computer. ( See Figure 4.6.2) It is the background for all programs and contains the commands needed for accessing those programs. It is like your personal work area.


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