The Ultimate Guide to Door Parts with Diagrams

Figuring out the essential parts of a door can be challenging. When buying new doors, you want to consider a few things. Framing, the locking mechanism, and the number of panels are some essential parts of a door.

The right door resists extensive use, reduces noise, and enhances the home’s interior decor. Knowing a door’s components helps avoid mistakes. It educates you concerning the jargon you may encounter while shopping for parts of a door.

Keep reading to learn more about the anatomy of a door.

Diagram of Door

Diagram of Door

Here’s a rundown of the primary door components to help you understand the terminology. We’ll also look at other minor parts of a door. It’s worth noting that some parts vary depending on a door’s design.

Door Panel

The door panel makes your door frame look complete. Smaller panels go between the stiles, rails, and mullions to create a complete structure. Also known as a slab, it fills the frame built by the rails and stiles of the door.

Door panels are the fundamental components of the door that swings back and forth. Wood or glass panes are ideal options for the door panel section.

Glass panes are typical in double doors. They add a decorative element to your exterior doors. Using glass enhances the curb appeal and allows interior doors to let in more light.


Rails are the horizontal parts on a door panel. Doors have a top, bottom, and mid-rail. The mid-rail, for instance, is the horizontal part that spans the width of the door.

It forms the door panel’s basic structural foundation on most residential door frames. Not all exterior doors have a top, bottom, and mid-rail.


Stile is the narrow vertical component on either side of a door panel. There are two panels on both vertical edges of a door frame; the lock stile and the hinge stile.

Keep these vertical components in mind when choosing the most suitable locking hardware. 

Hinge Margin

It’s the space between the door panel and the door frame. Hinge margins are usually 1/16″ while in swing or out swing but might vary depending on the door type.

They allow the door hinges to swing open and shut. Standard-size doors have three hinges, but bigger ones like the front door have more.

For sliding and high foot traffic doorways, pivot hinges are the most suitable. Barrel hinges are also ideal if you want concealed hinges.

Lock Set

Lockset refers to door handles, locks, latches, mortise, and strike plates. The lockset comprises all door hardware components allowing a door to latch and lock.

Locksets are all-in-one locking systems with everything you need to install a lock. Your lock set is helpful as it prevents any forced entry.

Mortise locksets are latch and doorknob sets that fit into the standard rectangular pocket on the edge of an interior door. The locking mechanism is simple to install and replace.


A mullion is similar to a stile. It’s the vertical component separating two panels in the middle of the front door, right between the rails. A mullion is a fixed panel or detachable frame component.

It separates patio doors, glass sections, or paneled areas. Mullions divide the door vertically down the middle, intersecting the lock rail.

Door Sweep

A door sweep, also known as a door sill, is a small strip that extends to the bottom of a window or door frame. Door sweeps are among the essential parts of a door as they keep air, water, and undesired creatures out of your home.


Molding is a functional and decorative element on window panes and doors. It’s a flexible material that holds doors in place and prevents them from swinging through door frames.

Because doors have open gaps on the outside edge, molding prevents light from escaping into and out of rooms.

Main Parts of a Door Frame

Main Parts of a Door Frame

A few parts of the floor frame come in handy when making your door opening or patio doors sturdy. These parts of a door frame are worth mentioning.

Door Casing Trim

The trim around a door frame, also known as doorway casing, is added to hide unattractive construction gaps between the frame and the plasterboard.

Door casings have a dual purpose. They enhance the door’s appearance while acting as a proper seal that hides the gap between the wall and the head jamb.

Basic doorway casings are made up of three main components. There are two long trim pieces on either side of the door frame and a shorter head casing to finish the framing. The casing fits the interior wall of tall narrow windows.

Head Jamb

The head jamb is the top horizontal part of a door or window frame. The central role of jambs and door frames providing long-term support for the door. When the door is hung, this framing supports it.

Strike Plate

The strike plate is mounted on the door jamb where the door’s bolt hole and the bolt connect. Strike plates attach to the door jamb using screws.

You’ll need screws to secure the metal plate to the door frame. A high-security strike plate should include at least four screws, each measuring at least three inches in length.


The threshold is the wood or metal strip across the door frame’s bottom. The goal of a threshold is to close the gap between the bottom of a door and the floor. It acts more like a door sill.

Thresholds work in tandem with door bottoms and weather stripping to seal the opening and keep out air, rain, and snow. They keep cool air inside while keeping hot weather out in the summer. Insulation not only helps to keep utility bills in check but also minimizes energy waste.


A transom is a small window or horizontal crosspiece that sits above a door or, sometimes, a window. Transoms divide the structure of a door. They’re common in window frames, lights, hinged flaps, and other decorative elements.

Transom windows get their name because they sit on top of the transom. It’s the beam that connects the top of the window or door to the rest of the wall.

Weather Strip

Weatherstripping is the process of wrapping a piece of material around the bottom, top, and sides of windows and doors to keep them from drafts. It functions as a door sill.

The composite materials, made of plastic or metal, work as a physical barrier to prevent cold air from seeping in and causing heat loss in the winter or vice versa in the summer. 

Jack Studs

A jack stud is a vertical structural element that stands beneath and supports a header, transferring its loads down to the bottom plate and, eventually, the structure’s foundation. Its length defines the header height and is necessary for rough window and door openings.

Door Latch

Door latches are parts of a door used to close and fasten doors. A door latch prevents the door from swinging while enabling normal function when the latch is released by attaching a fastener to two different surfaces, most often the door and the frame.

Door Header

It bears the weight of everything constructed above the door opening, including some of the ceiling and, in some cases, roof structure and panels.

A door frame need not have a header even though it is crucial for structural support. Door headers are necessary for large doors, outside door frames, and load-bearing walls.


The doorstop is a piece of wood affixed to the door frame that keeps the door from swinging open after it has been closed. Closing the door without a doorstop would cause it to swing through the frame, damaging the hinges.

In some instances, door jambs have a raised section built into them that serves the same purpose, bypassing the need to use it on your door frame.

Door Jamb

The frame and door jambs’ purpose is to give the door sturdy support. The door depends on this framing when it is hung.

When remodeling or installing brand-new door jambs as part of the door frame, reliable structural support should be in mind. The door jamb supports the door’s weight on the mounting hinges. It also determines the efficiency of the locking mechanism.

Frame Reinforcer

Your door frame needs reinforcing to withstand a home invasion. Your frame can be reinforced most effectively by adding a steel coating to stop them from fracturing.

High-gauge steel must be positioned over the door jamb during installation and fastened using long screws. On each side of the doorway, the screws should reach the wall studs. Your door jamb will be fully fortified as a result.

Parts of a Door Knob

Parts of a Door Knob

Door Handle

A door handle could mean knobs, bars, and door latches. A door handle is a mechanism that assists in unlatching, opening, and closing a door panel.

Door handles are an essential element of door hardware. Its functionality, placement, and design are crucial factors when purchasing a knob.


Housing is the lock’s outer shell, which houses the rest of the lock’s functional components. A cylinder containing the lock mechanism and keyhole sits inside and in the center of a locking knob.

Door knobs are fixed in the door using hardware such as screws and other metal items. It all depends on the design.


A typical lock will have two knobs or handles, one on the inside and one on the outside. Knobs come in different finishes, from antique brass to rubbed bronze and stainless steel.

A thumb turn on the inside knob or handle allows you to engage the locking mechanism. The outer knob or handle usually has a lock cylinder that requires a key to engage and disable the lock.

Mortise Plate

parts of a door

The mortise is a pocket that curves out to accommodate the lock. The mortise plate, a small metal plate on the edge of the door adjacent to the latch, guards the lock against damage.

Key Cylinder

You’ll need to insert a key into the lock cylinder and adjust the lock pins to disengage it. You turn the key inside the lock cylinder to unlock your front door.

Frequently Asked Questions (FAQ)FAQ

What's the most common front door material?

Each material for front doors—wood, fiberglass, or steel—can offer a different set of advantages to support you in realizing the unique objectives you have for your house. Think about panel styles, customizing options, and maintenance needs as you explore various materials.

How many panels should interior doors have?

Interior doors with six panels and a solid core are suitable for most homes. You get to combine the benefits of a solid structure with the typical interior door’s appearance. Six panels are the standard for doors because they make a sturdy, stiff, and long-lasting door even in moist conditions.

Where can I find door parts?

You can purchase door parts from popular retail chains like Direct Door Hardware and Build with Ferguson. There are also sites like Lowe’s and Home Depot with physical stores.

What's the standard thickness of a front door?

Most doors will be 1 3/4 inches thick regardless of the design or style. Although this thickness is considered standard, the material may cause a slight variation. Depending on their material, well-insulated doors could be a little thicker.