What are the Parts of a Door?

If you’re getting ready to install a sliding barn door, a new French bypass door, or any other type of interior or exterior entryway door, it’s essential to understand how the different parts of a door work together. There are as many types of doors as there are styles of architecture, so it’s important to know what type of door you’re planning to install. Before you get out the sledgehammer, saw, and drill, you’ll want to learn about the different parts of a door, including:

What are the Parts of a Door?

• Casing
• Sidelite
• Transom
• Slab
• Top Rail
• Stile
• Door Panel
• Bottom Rail
• Bore
• Door Sweep
• Door Jamb
• Door Stop
• Threshold
• Weather Stripping
• Strike Plate
• Hardware

By acquainting yourself with the various parts of a door, you’ll be better equipped to build a door yourself. You can also ensure your custom-made door is installed correctly, and you’ll be ready to help a friend or neighbor figure out what door looks best in their home.

What are the Parts of a Door?

Casing

Nearly every door you’ve walked through has casing. The casing on a door is the decorative trim on the outside of the doorway. Think of it like a picture frame, and the door is the picture. Depending on the type of home and door, casing can be very simple or extremely ornate.

If building or installing a sliding barn door, there is no need for casing since the barn door completely covers the opening and several inches on either side. For those that need to install a new storm door, patio door, or pocket door, casing is often optional, as it will neither enhance nor take away from the door itself.

Minimalist doors are often free of casings to go with the minimalist feel. If, however, you’re planning to install a regular swing door or want to jazz up the doorframe of your interior door or exterior door, then you’ll want to install a casing.

Casing can be as simple as mitered casing which uses side pieces and a head piece with angled edges. This creates a put-together look that is both simple and elegant. For a more dressed up feel, you can choose butted casing. Butted casing uses two side pieces and a head piece that rests on top of both side pieces. This style works best for tall doorways and high ceilings. Whether installing a new door or fixing up an old one during a door repair project, casing is a great place to start.

Sidelite

Similar to a door’s casing, the sidelite is more about style and beauty than necessity when it comes to installing a door. Sidelites are vertical strips that run parallel to the doorframe and are made of glass. They are both beautiful and functional. They’re a great option for bringing more natural light into the door’s entryway.

Sidelites can be customized to any door and made to match the architecture of your home, whether your house boasts a Victorian or a modern feel.

Thanks to modern technology, a sidelite can be very eco-friendly, allowing the sunlight to warm a room during winter while keeping harmful UV rays out during the peak of summer. You can also have custom-built shades fitted to provide extra light filtering when needed during the summer months.

Transom

The transom is a horizontal bar that runs across the top of the door frame. This area is another place where you can insert a window, known as a transom window.

If you’re inserting a sidelite into one or both sides of your doorframe, then a transom window can round out the overall appearance and provide even more light inside your home.

Whether you choose a window or a solid wood piece, the transom provides a polished, finished look to your overall door structure. This feature is most often used on exterior doors and sometimes windows if the aim is to provide more light than the windows allow into a home.

Slab

When looking into renovating your home, you’ll run into the word ‘slab’ when considering options for updating your door. What is a slab door? The slab is the door itself; the literal slab of wood.

A door slab can be customized to be placed on barn door rollers and made into a sliding barn door, or you can add hinges and make it a hinged slab door or swinging slab door.

When choosing a door slab, your choices most often have to do with what type of wood you desire, such as alder, maple, or cedar. You can customize the slab to your needs, including the dimensions, have it hinge system, door knob, swing direction, and desired finish.  

When ordering a slab, you will need to specify whether you want a hinge or barn door hardware. If you’ll be using the slab as a barn door, then you’ll need to also order rollers for the door to function. If you’ll be placing the slab in a regular doorway, hinge placements will need to be added.

If you don’t want to do the entire DIY project yourself, you can also opt for prehung door slabs that come ready to mount.

Top Rail

The top rail on a door is the upper-most horizontal piece that connects both sides together. On a hanging barn door, the top rail is the piece that connects all the vertical slats together and keeps them square.

Top rails on wood doors are often “invisible” because they are painted or stained along with the rest of the door to make it look like one continuous piece. Nearly every door has a top rail, so if you look closely, you might be able to find the seam.

On a sliding glass door or a sliding patio door, the top rail is often a metal piece that forms part of the frame that holds the glass together.

Stile

The stile is a vertical piece that joins the top rail, middle rail, and the bottom rail together. On a sliding barn door, the stile is the vertical piece that holds the middle panels in place that form the common ‘z’ or ‘x’ design. On regular doors, when painted, you can’t see the stile, as it seamlessly adheres to the rest of the door to form a solid singular piece.

Door Panel

A door panel is what you think of most often when you think about a door. These are the pieces that fit inside the frames and can be raised or flat to form the central design in most slab doors.
Panels are completely customizable and can be made to reflect any architectural style. On a storm door, sliding patio door, French door, or window, the panel is typically one solid glass piece. Custom door paneling is most often customized on an exterior door to provide an extra degree of polish and flair for an overall look.

If glass, the door panel can be customized depending on the level of clarity desired. Glass can be completely clear, tinted, or styled with a fluted design, an antique look, frosted appearance, or even a retro design that matches many décor styles.

Whether you’re working with a wood or glass door panel, the most important thing to know is that this part can be completely customized to reflect your individual personality, décor theme, and the architectural style of your home. Panel customization is just one way to take any type of door and make it your own.

Bottom Rail

The bottom rail on a door is the lowest horizontal piece that is positioned to form the bottom of the door. It is held in place by the vertical stiles. When a door is painted, you often cannot see the bottom rail. If the door is made of wood and stained, you can see the horizontal piece, but it is flush to the rest of the pieces of a door and can appear to look like one solid piece.

In many commercial businesses, apartment buildings, and some residential homes, a kick plate is installed over the bottom rail. A kick plate is a sheet of metal attached to the bottom rail that protects the wood from damage when someone kicks the door open if their hands are full. Kick plates are common in high-traffic areas, such as front exterior doors, doors leading from a garage into the home, and kitchen doors.

Bore

When ordering a custom door, you’ll need to know what size you want the bore or bore hole. You’ll also need to know whether you want a single bore or double bore.

Exterior doors need a double bore. This allows two holes to be bored that will serve as the place for both the door knob and the deadbolt. A small cross bore hole will be inserted for a place that allows the deadbolt lock as well as the door knob latch to extend into the door frame and hold the door firmly in place.

Interior doors most often need a single bore. The single bore is made for a door knob only. For interior doors that need to lock, many homeowners purchase a door knob that can also lock instead of boring a second hole for a dedicated locking mechanism. If you have an exterior back door that needs a deadbolt installed, this door will also need a double bore setup.

When it comes to dimensions, most bore holes are cut anywhere from 2 3/8”  to 2 1/4” from the edge of the door. This provides enough room for the door knob and locking mechanism to fit firmly in place.

Door Sweep

On the very bottom of a door, just under the bottom rail and kick plate if you have one, is where the door sweep should be installed. Every door has a slight gap on the bottom. This gap is conveniently covered with a door sweep to seal the inside of your home from dust and outside moisture.

The door sweep is typically made of a horizontal metal piece that is screwed into the bottom of the door and a rubber piece attached to the metal. The door sweep is commonly installed on the outside of a door to prevent outside dirt and moisture from entering the home.

Door Jamb

The door jamb is the vertical piece of the door frame that serves to hold the weight of the door in addition to keeping the door frame square. If the door jamb is out of alignment, your door won’t open or close correctly, and you could have structural issues if it is not fixed. Door jambs are necessary for a wide variety of doors, including single, sliding, folding, and double doors.

The door jamb is often confused for the door casing or the decorative elements on the outside of a doorway. The door jamb, however, is only visible when you open the door. If you look at the place where the hinges are located, you’ll see the door jamb. The jamb is on both sides of the door to serve as structural support for the entire doorframe. Hinges can be located on one side while the recess for the deadbolt and door latch is on the other. If the door jamb is out of alignment, it may prevent you from closing it or locking it correctly.

Door Stop

Doors that have a heavy swing or open easily may benefit from the installation of a door stop. These simple items are installed at the bottom of a door and can be attached to the wall, floor, or even an existing door hinge depending on which stopper you desire.

The point of a door stop is to prevent a door from swinging inward too quickly and crashing into the wall behind it. Depending on the heaviness of a door, if swung too forcefully, the door handle could dent or even damage drywall if unimpeded. The door stop is used as a protective measure to prevent this from happening.

Threshold

The threshold is often made of metal and is the part of your door that you walk on or over without even noticing. This piece serves a very specific, important purpose.

The threshold is most often made of metal but can be made from wood, laminate, and even stone. It is a slightly rounded piece that fits into the bottom of your doorway and makes your doorway as watertight as possible. This piece runs across the entire doorframe and greatly improves the energy efficiency in a home by preventing drafts from entering or conditioned air from escaping. It also keeps rain and moisture from entering into your entryway through the gap in the door.

This important piece of your doorway can also serve to prevent pests from entering your home. If you live in a developing neighborhood or a rural area, pest deterrent will be especially important, and a proper functioning threshold is crucial.

Weather Stripping

Though doors are crafted to be as tight as possible, there are still small openings around the top and sides of the door that can allow wind and water to come inside. To prevent this from occurring, weather stripping should be placed around the sides and the top of the door itself.

By placing weather stripping on your door, you effectively seal the inside of your home from the outside elements and make your home more energy efficient. The most common form of weather stripping comes in felt and foam tape, which can be applied directly to the door. This project only takes minutes to install and helps seal your home from the elements all year long.

Strike Plate

The strike plate is one of several components that go largely ignored on a door. Like other parts, however, the strike plate is an important part that homeowners cannot—and should not—go without.

This plate is made of metal and is made to cover the area of the door jamb that has holes to receive both the deadbolt lock and the door knob latch. The purpose is to provide protection to the jamb from repeated use when the door is locked and the bolt is inserted into the jamb. It can provide extra support for softwood jambs, in addition to providing added security against home break-ins.

If a potential home intruder tries to break the door by kicking it open, the strike plate will help prevent this from occurring. Without the strike plate, enough force can cause the door jamb to break where the deadbolt locks the door. With the plate, however, an intruder is often unable to break the door open by force.

Hardware

Hardware is one of the most fun parts of door installation, aside from designing the door itself. If the door is a picture and the casing is the picture frame, think of the door handle like the artist’s signature. Any picture would be incomplete without it.

The hardware of your door can be as unique as your door and the architecture your house boasts. Depending on the type of door you’ve installed in your home, you’ll need varying amounts of hardware. Barn doors, for example, require sliding door hardware.

This means you will need a door handle for pulling the door open and shut in addition to the mounting and rolling hardware needed to hang the door in its place.

For exterior doors and interior doors, in addition to pre-hung French doors and sliding patio doors, you’ll most likely only need to pick a door handle. It’s essential to adjust the handle to match the color, style, and feel you’re going for with your door.
If the front of your house boasts a western, rustic, or shabby chic feel, you’ll benefit most from hardware that is flat black, raw steel or oil rubbed bronze.

Modern doors will look best with hardware that is matte black, bonded chrome, or stainless steel to match with the contemporary feel of the home.

For custom doors, you can enjoy creating a unique look and feel with metals and colors such as forged iron, modern gold, copper, antique pewter, or even distressed white.

Feel like matching the color you painted your door? Go right ahead and custom order hardware that is colored to match. There are no limits on what you can do when it comes to making your front door look just the way you want it.

Don’t forget your interior doors, as well! Customize the hardware you choose for your French doors, sliding barn doors, patio doors, and other interior door options. Hardware can be just the finishing touch you need to make your door pop and complete the interior design you’re looking for.

Add the Finishing Touch

In many homes, exterior doors and interior doors are often given little thought and the least amount of budget when it comes to home renovation or upgrades. In reality though, these gateways to your happy place should be given the most attention.

Your exterior door is what you’ll see every day when coming home from work. Exterior doors, such as those for your front porch and patio are what will greet you and your guests when enjoying time at home. Entries should be just as welcoming as the rest of your house. They should also match the interior feel as much as your décor.

Doors are quite complicated when you get into their makeup and structure, though each can be customized to match the look, feel, and ambiance of your home. Don’t leave the look of your home up to builder grade installations when you could have a custom-made door installed. Increase the wow-factor of your home and make your doors look one of a kind.