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.


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.

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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


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.

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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.

Parts of a Door: Learn About the Anatomy of a Door (5)

Parts of a Door: Learn About the Anatomy of a Door (6)

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.

The experts at Marvin are experienced at working with architects, builders and homeowners. Connect with a dealerin your area to visit a showroom and to discover which Marvin products will work best for your next project.

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What is the most important part of a door? ›

There are many connecting parts that work together to create a strong barrier against intruders as well as elements like air and water.
The Most Important Parts of a Front Door
  1. Transom. The window above the door. ...
  2. Door Frame or Door Jamb. ...
  3. Mull Post. ...
  4. Door Slab. ...
  5. Sill. ...
  6. Sidelite. ...
  7. Brickmold.

What is the structure of the 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 door frame 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.

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 a door joint called? ›

A hinge is used every time you open a door, close a cabinet or lift the cover of your freezer chest. The two pieces of interconnecting metal secured by a pin perform important tasks, and you may tend to overlook them until you can't open or close a door correctly.

What is the piece called at the bottom of a door? ›

The door sill is the very bottom part of the door frame that rests on the floor.

What is the little 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. The guards checked at the peephole before entering.

What is the bit at 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. You don't usually find them on interior doors, but most exterior doors will have a threshold.

What is the mechanism in a door called? ›

A lever is a mechanism you push down to open or close a door. Spindle: A metal bar that you insert through the latch and handle. The spindle connects the handles on either side of the door and allows the latch bolt to operate.

What is the wood around a door called? ›

ARCHITRAVE: An architrave is the piece of wood that goes around the door frame to cover the gap between the wall and the door frame.

What is the structure over a front door called? ›

A portico is a little roof that goes above your front door and is supported by columns. They date back to ancient Greece, when columns were a staple of architecture and found anywhere and everywhere.

What is a door beam called? ›

A lintel or lintol is a type of beam (a horizontal structural element) that spans openings such as portals, doors, windows and fireplaces. It can be a decorative architectural element, or a combined ornamented structural item.

What is the angle on a door called? ›

Beveling a door is the process of shaping the leading edge of the door at an angle. The bevel is usually 2 to 3 degrees and is done the entire length of the door on the lock side. The reason for beveling is to allow for a tighter fit of the door to the jamb when in the closed position (see illustration below).

Did you know facts about doors? ›

8 Fun Facts About Doors
  • The World's Largest Building Needs a Pretty Big Door. ...
  • Automatic Garage Doors Aren't a Modern Marvel. ...
  • Who Knew a Colorful Door Could be Rebellious? ...
  • Doors Influence Energy in Feng Shui. ...
  • Romans Were Very Open About their Door Décor. ...
  • Janus was the God of Doors. ...
  • Dreaming About Doors Can Have Meaning.
Aug 12, 2014

What is a door function? ›

Functions of a door:

It is provided to give access to the inside of a room of a house. It serves as a connecting link between the various internal portion of a house. It provides lighting and ventilation to rooms. Controls the physical atmosphere within a space by enclosing it. They act as a barrier to noise.

What forces are acting on a door? ›

Opening a door requires our hand to apply force by pushing and pulling which is a contact force. There is some frictional force in the door hinge, against that we apply force. The hinge friction is again a contact force. Was this answer helpful?

What is the gap between doors 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 holds a door in place? ›

Latch. 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.

What are two doors together called? ›

Side by side doors, also known as double doors, are two door configurations where both doors are next to one another. Another name for this type of doors is a French door. The doors can either be active or inactive.

What is the push thing on a door called? ›

A crash bar (also known as a panic exit device, panic bar, or push bar) is a type of door opening mechanism which allows users to open a door by pushing a bar.

What is the little window in a front door called? ›


A sidelight is a fixed glass panel with a frame that is mulled, or installed, on one or both sides of an exterior door. Sidelights, like doorlights, can consist of decorative or clear glass in a variety of sizes.

What is the plate behind a door knob 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 the thing called that connects the door to the wall? ›

The door frame is what connects your door to the walls of your home. The frame consists of a head jamb or simply a head, which is the uppermost horizontal part of the frame.

What is red dot on door? ›

Throughout the world and across different industries, Red Dot is seen as the award for ground-breaking design. The sought-after Red Dot seal of approval is awarded only to world-class designs that demonstrate superior 'quality and innovative power'.

What is the top lock on a door called? ›

Deadbolts provide the highest level of front door security. To ensure your door locks provide solid home security, choose locks and deadbolts that are pick-resistant and bump proof.

What is a door with a top and bottom called? ›

Dutch doors are essentially a single door that is split in the middle to allow the top half to open while the bottom half remains shut. They are secured together with a latch that allows homeowners to keep the door as one when needed.

What is a door wedge called? ›

A doorstop (also door stopper, door stop or door wedge) is an object or device used to hold a door open or closed, or to prevent a door from opening too widely.

What is a jamb on door? ›

Simply put, the door jamb is a specific part of the frame. It's there to take the weight of the door, as well as help keep the rest of the frame square and stable. Your hinges are affixed to the jamb on one side of the door, while the bolt passes through the jamb on the other side.

What is door lintel? ›

The door lintel is a horizontal beam fitted across the top of the door opening to support the bricks above the door structurally. Over the years, lintels have been made from numerous materials, but today they are typically made from steel or prestressed concrete, depending on the door opening's size.

What are the parts of door trim called? ›

Quite simply, it's a moulding profile which frames (or trims) a door or window. Casing is functional as well as decorative. The main purpose of casing is to surround all doors and windows, covering any space or gap left between the drywall and frame.

What is the thing called that holds a door open? ›

A doorstop (also door stopper, door stop or door wedge) is an object or device used to hold a door open or closed, or to prevent a door from opening too widely. The same word is used to refer to a thin slat built inside a door frame to prevent a door from swinging through when closed.

What are the trims around doors called? ›

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 the strip at the bottom of a door called? ›

A door sweep is a long strip of metal that holds a seal made of a material such as neoprene, silicone, or a nylon brush. This long strip of metal is surface mounted to the bottom of the door.

What is the hardware on a door called? ›

Lockset: is the Handle hardware that makes up the locking or latching mechanism that can usually be found on a door. Functions (Lock): A set of operating features for a particular type of lock or exit device which make it suitable for a specific application.

What are door guards called? ›

A door edge guard, also known as door edge trim, serves to protect that precious paint at one of the most vulnerable points on your vehicle, which is right there in the name: the door edge. Every time you or a passenger swing a door open, there's a risk of hitting something that can damage the paint along the edge.


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