If you’re going to install a new exterior door or build one and you’re overwhelmed with the dozens of terms floating around concerning the parts of a door, this is for you. We’ll break down the parts of a door so you can get a good understanding of how all of the pieces and parts come together. Learning about the parts of a door makes it easier to talk to dealers or contractors to ensure that you get the correct door for your projects.
There are several different parts to a doorway, and knowing the technical terms can ensure that you pick out a door that works for your style while being functional. The portal and the archway by Wayne S. Grazio / CC BY-NC-ND 2.0
23 Parts of a Door
Did you know that there are over 20 parts to any door? You may know these parts by some other term, but we’re going to pick out the technical terms and describe each one for you so you know exactly what someone is referencing when they talk about them.
If you have double doors for your exterior door on your home leading out to your patio or porch, you’ll have the astragal as part of the door that covers the seam between the two door panels. It gets weather stripping on it to prevent water and wind from slipping through into the house.
- Bore Hole
A bore hole is the larger hole that contractors drill into the face of the door to accommodate the lockset, specifically the door knob. The size of your bore hole will depend on which lockset you pick out for your new door.
3. Brick Mold
The brick mold is an exterior casing trim that comes designed to conceal the gap between a door or window frame and the exterior surface of the wall. Brick mold is usually thicker than most interior casing trims, and it provides you with a nice buffer between the door and brick or whichever over cladding you have around it. Brick mold can have aluminum, wood, fiberglass, PVC, or compositie materials in the design, and it’s the part that the store or screen door attaches to.
Door casing trim is specially designed to help hide any gaps between the door frame and the interior wall’s surface. They’re usually thin wooden strips that go right up to the edge of the doorframe and look like trim.
5. Door Frame
Mulls, head jambs, and side jams are all parts that come together to form the door frame. Door frames on residential homes are usually made out of wood, but you can also find them made out of fiberglass, aluminum, or other composite materials. You can purchase these door frames that are primed and ready to paint, or you can order them straight from the factory in several colors with a factory finish.
6. Door Sweep
The door sweep is the weatherstripping that gets installed on the bottom of the door panel. As the name suggests, it works to create a weather-resistant barrier between the sill and door panel to block any drafts that may try to come through.
Glazing is a fancy word for the glass part of a door. The glazing featured in newer exterior doors has at least two layers of glass, and it can have up to three. The manufacturers inject inert gas, typically argon, between the glass layers to give you more insulation. They then add almost invisible coatings to the glass to help dictate how much heat and sunlight comes through the window or gets reflected away from it. You can get enhanced glazing with tints and laminations that provide decorative touches, increase your privacy levels, and make it stronger to breakage.
Grilles are smaller bars that give you the illusion that a single piece of glass is actually small pieces. However, you can remove them to make cleaning the glass easy. You can also get Grilles-Between-the-Glass (GBG), and these get installed right between the glass panes to make cleaning and everyday maintenance a quick and easy process.
9. Head Jamb
This part of a door is very simple, and it simply refers to the top horizontal section. So, if you open the door and look up, it’s the top part of the frame in the doorway.
The hinge is the part of a door that lets the door swing open or closed. A standard-sized door will come with three hinges on it, but bigger doors can easily have four or more hinges. The hinge finish and color will typically match whatever finish your lockset has on it to create a cohesive design.
Heavier doors will require more heavy-duty hinges than you’d use on most residential doors, and they usually need three hinges to the standard two. Church Door in Riverside by Craig ONeal / CC BY-SA 2.0
11. Mullion or Mull
When you join a door and a window or two individual windows, you’ll see a seam between the two units or the frame. This is the mull or mullion. In most cases, the door jamb gets joined to a sidelight jamb or window. You’ll usually have a piece of trim called the mull casing in place to help hide and seams.
12. Muntin Bars
Until the mid portion of the 19th century, bigger panes of glass were very expensive to make and fragile. To combat this, muntin bars got joined together to create a larger sheet of glass from smaller panes to help improve the strength while lowering the price.
This part of a door is also called a slab, and it encompasses the whole part of the door that swings open or closed. A full door panel usually gets divided up into smaller panels, and the manufactures set these panels between mullions, rails, and stiles to create a solid door.
If you look at your door, you’ll see very narrow segments that run horizontally. This part of a door is the rail, and the door comes outfitted with a top, bottom, and mid-rail to help add stability.
15. Side Jamb
The side jambs are the vertical parts of a door that you’ll see on each side of a window frame or door. The side jamb is also the part of the door that fastens to the framing using nails or screws.
The sidelights are the narrow, tall windows that you’ll find on both or one side of your door. This part of the door allows for more light to spill into the entryway, improves your views, and it can help to create a more welcoming look and feel.
The sills are the bottom parts of a door frame. This is the part that you’ll seal and fasten to the floor. On any door that leads to garages or to the outdoors, you’ll find this piece to help prevent drafts and gaps. You will have to prep the floor to install this part of the door.
18. Simulated Divided Lite Bars
Large glass panes or sheets are now less expensive to make without sacrificing durability. They’re also much more energy-efficient than their earlier counterparts, so muntin bars have largely given way to these bars. The bars sit directly on the surface of the glass to divide it up.
The stile is the vertical, narrow segment that you can see on either side of your door panel. One part of a door is called the lock stile and the one on the opposite side is called the hinge stile.
20. Stop Molding
You’ll see the door stop molding if you take a close look at the door frame. This molding aligns perfectly with the panel inside the frame, and the main function of this part of a door is to stop the panel from swinging right through the opening when you open or close it.
The threshold works as a protective part of a door that covers the sill. Usually, it has a sloped design to help it shed any water so the water doesn’t run straight down the door. Most thresholds are made out of very durable materials like fiberglass or metal because they have to be able to withstand a high amount of foot traffic as they enter or exit the home.
You want to install a threshold in your doorways to help protect the sill underneath it, and this is very important to protecting your floors on interior doors. Threshold! By pricklypeardesu / CC BY-NC-ND 2.0
A transom refers to the narrow window that is above a window or door. This part of the door usually doesn’t open. However, if they do, you’ll find that they have a hinged top like you’d get on an awning window.
When you have an exterior door, this part of a door will help fill in any gaps between the closed door panel and the frame. You’ll typically get a very flexible and resilient material like foam, rubber, or silicone to make it last longer.
Door Lockset or Hardware – 11 Parts
You can think of the door slab as the picture and the casing like the picture frame. Going with this visual, your hardware or lockset would be the painter’s signature. The type and design of this part of a door will depend on the door’s design. For example, sliding doors would require sliding door hardware with rolling and mounting pieces to hold the door together and a sliding door handle. Interior or exterior doors would need a door handle. You can choose from several textures and designs, including stainless, matte, chrome, steel, brass, or oil-rubbed bronze.
This part of a door is the one that keeps the door locked. When you turn the key, your deadbolt will push down to the mortice. Once it slots into this hole, the door is locked and it’s harder for anyone to break in.
The escutcheon is the decorative plate part of a door that you’ll see installed in the deadbolts, handles, and thumb turn. They get installed specifically to protect the door panels from scratches and dents to keep them looking nice.
The handle is the knob that you use to unbolt the latch to close or open your door. This part of a door comes in three main types. The types include a bed and bath handle that has an interior push lock button, an entry handle with cylinder keyholes, and passage handles that don’t have a locking system installed.
4. Housing and Linkage
You’ll find this part of a door in your sliding doors. They’re usually in aluminum or metal housing, and the linkage is responsible for keeping the door in a locked or unlocked state each time you open or close the door.
5. Key Cylinder
This part of a door is better known as the lock body. It’s the part where you insert your key to open or close the door.
Just like this term implies, this is where you push into the lock. The interesting thing about this part of a door is that there is a huge range of keyhole designs you can get. You can pick out the cylinder lock that unbolts your door’s lock using a rotating hole, and the multi-point lock has several lock points inside a single handle.
In the simplest terms, this part of a door is the one that is responsible for keeping your door closed. Once you push the knob down or rotate it, it pulls the latch to open the door.
8. Mortise Plates
The mortise plates function as a protective part of a door. They offer reinforcement that makes deadbolts, latches, and door panels stronger so they’re able to withstand forced entry or breaking in much better.
9. Spring Bolt
The other type of latch other than the deadbolt is the spring bolt. A spring clip holds this latch together, and it opens the door when you compress it. When you release the compression, this part of a door will lock the door.
10. Strike Plates
The strike plates work to cover your door jamb area. It’s the part of a door that gets the latch and deadbolt lock. The main function of this part is to protect your door jamb when you use it repeatedly when you constantly lock or unlock the door. Having strike plates on your door can also make it harder to break into your home. Any door jambs that don’t feature strike plates give in much easier to force.
11. Thumb Turn
This part of a door will only be on your door if you have a deadbolt-style lock installed. It’s on the interior side of your door with the key cylinder on the exterior side. You can unlock your deadbolt by twisting the thumb term from the inside, and you have to use a key to lock or unlock it from the outside.
Door Hinges – 4 Parts
The door hinge features two components that get attached together in a way that allows it to swivel. The mechanism that attaches them is typically a pin that looks like a long bolt without any thread.
- Knuckles – These are the interlocking tubes on the leafs that slot together to allow the pin to connect them while allowing for a swivel motion.
- Leaf – Any hinge comes with two leafs, and one attaches to the door. The other leaf will attach to the door frame, and you use a pin to attach both leafs.
- Pin – The pin is the bolt-like object that connects the two leafs.
- Screw Holes – The screw holes are the areas on both leaves where the screws go to attach them to the frame and door.
Choosing a hinge style can help you pull your door’s look together, and it’s also important that you get enough hinges to support the weight of the door itself. Yellow door by mark dyer / CC BY-NC-ND 2.0
Seven Popular Types of Hinges
There are several different types of hinges you can pick out when you’re looking for parts of a door. You can find the one that matches your decor the best to create a pretty, seamless look.
- Back Flap Hinge – You’ll use this type of hinge where the shutters are fixed and thin. They go on the back side of the frame and shutter.
- Butt Hinge – This hinge style is commonly used for windows or doors made out of cast iron, steel, or malleable iron. You screw them into the edges of the windows or doors and to the sides of the frames.
- Garnet Hinge – You’ll get a wrought-iron strap that fastens to a metal piece plate called a shutter. This hinge has a longer arm that you screw onto the shutter and a smaller plate that gets mounted on the frame. You find this hinge on plank shutter doors.
- Nar-Madi Hinge – if you have a heavy door, this may be the part of the door hinge you need. It features pins that you mount to the walls or frame. You fix the strap onto the door’s shutter using a durable pin.
- Parliamentary Hinge – This is a specialized hinge you can use to hang doors. You’ll use them when you get a more narrow opening and you need to be able to open the door without any obstruction.
- Pin Hinge – This hinge is typically found on heavier doors. You can get three pins, but it’s possible to remove the middle pin by fastening the two leaves separately to the shutter and frame.
- Strap Hinge – You can use a strap hinge instead of a T-hinge for braced or ledged doors. They’re popular on heavier doors like gates and garages.
Sliding Doors – 7 Parts
The final section of this article is going to give you a quick rundown of the seven parts of a door for a sliding-style door. They’re very popular to use when you need a door to go out to your patio or deck because they allow a lot of light in.
- Hangers – The hangers are the top brackets where you attach the top section of your sliding door. This part of a door is usually big enough to hide the top rails or tracks.
- Insulated Glass – You get insulated glass when you combine two or more glass panels inside your sliding glass door frame. They get polished with argon or krypton to give you much better heat insulation.
- Interlocking Meeting Rail – This part of a door is the point where the two glass panels in the sliding glass door meet when you close the door.
- Operable Panel – This refers to the glass panel in your sliding door that gets enclosed in either a metal or steel frame.
- Rails/Tracks – The rails or tracks are the slim structures that you find below or on top of the door sections. The sliding door will smoothly roll along this part of a door to open and close.
- Rollers – The rollers are on the sliding door’s bottom area. This is how your glass panels slide open and closed.
- Stopper – The stopper is the protective piece that usually features a hard rubber design, and you’ll find it on both ends of the track. It stops the rollers from high-impact closing or jerking to a stop to protect the glass panels in the door.
We’ve outlined the parts of a door for you to give you a good understanding of what parts people are talking about, and this can help you go and talk to contractors or businesses that sell doors with confidence. You can now be sure that you get a perfect fit for your wants and needs each time you buy a new door or upgrade your existing one to match your design aesthetic.
Jen is a master gardener, interior designer and home improvement expert. She has completed many home improvement, decor and remodeling projects with her family over the past 10 years on their 4,500 sf Victorian house. She is also a passionate farmer who keeps goats, chickens, turkeys cows and pigs on her farm, and an instructor for her community’s Organic and Sustainable Farming project.