46 Different Parts Of a Door, Sliding Door and Door Frame (Include Knob)

Last Updated on November 17, 2021 by Kimberly Crawford

Doors are always taken as a default part of a house or a room. On a more subjective note, doors are commonly associated with labyrinths, transitions, opportunities, and new beginnings.

But in a practical, engineering/architectural sense, there are actually more than twenty parts of a door and for sure, you only know seven of them at least.

In this post, we will cover all the parts of a door that you should know about. 

Related: Parts of a roof

Parts of a door

1. Frame

door frames

Basically, this is the entire structure that supports the door. It is known more as the door sash. It is composed of the header, the door jamb, and the sill.

Door frames can be made of many materials including wood, metal, and aluminum, among others. 

door jambs
Door Jambs

2. Head jamb

It is also called the header and it is located at the top horizontal section of the door or a window frame. 

3. Side jamb

On the other hand, side jambs are the vertical pieces located at each side of a window frame or a door. They are attached to the frame with nails and screws. 

4. Sill

It is the same as the threshold. It is found just below the header whose function is to maintain the structural integrity of the entire door. It is usually only found in exterior doors. 

5. Horn

This is a part of the door frame. It is that projected piece located at the top and bottom of the door frame enabling the frame fixing in the door’s opening. 

6. Holdfasts

This is hardware (metal) fitted in door frames. Three holdfasts are inserted in each side of the frame. 

7. Rebate

This one is a deep groove found at the door frame’s edge for a tighter fit. There are single and double rebates. The latter is more used now because they are thicker than single rebates, lessening chances of breaking-in. 

8. Threshold

This one is that round piece located in the bottom part of the doorway whose function is to make the door as watertight as possible and along the entire frame to make it airtight or to prevent draft in the door gaps. Most importantly, it is a pest deterrent. It can be made with laminated wood, natural stone, or hardwood. 

9. Transom

This one is the horizontal bar that you will see on top of the door’s frame. This is also the structure into which transom windows are inserted. Having a transom window actually gives more natural light especially if you add sidelights. Overall, it is a good choice to have a more polished-looking door. 

10. Fanlight

This one is like a small window located on top of the transom. They function to let it have more natural light and better air circulation. 

11. Casing

This one is the frame that holds the solid wood that makes the door. It is like the picture frame and the picture would be the door. They can have ornate designs or just a simple square trimming. Sliding and minimalist doors do not have casings. 

12. Glazing

This one is that glass piece inside a window or door. The glass is reinforced with two to three layers of glass. For better insulation, it is usually reinforced with argon and other invisible coatings. It can be polished with laminations or even glass tints for decorative purposes or to lessen the heat coming into the house. 

13. Sidelights

Like casings, sidelights are both decorative and functional. They are usually made of glass. Sidelights are vertical strips running in parallel at the door frame. On the more functional side, it adds more light to the doorway. They can be customizable and modern designs now infuse UV blocking capacity during summer.  

14. Weather-stripping

No matter how airtight or watertight a door could be, there are still very minute gaps where air and water could come in. As such, you need weather-stripping. It is installed on top and on the sides of the door, giving you an added energy-saving feature and protecting the indoors from harsh elements. Weatherstripping comes in foam tape or felt tape. 

15. Brick mould

This one is an exterior door trimming which function is to conceal the door’s exterior surface and the door frame. It is also the piece where a storm or screen door is attached. As such, it is usually thicker than the other trimmings in the door. It is usually made of PVC, fiberglass, aluminum, wood, and other composite materials. 

16. Door sweep

This one is usually found on the bottom door along with the kick plate and bottom rail. It is installed to add additional dust-proofing and to prevent more moisture inside the home. It is placed in the bottom gap in the door and screwed from the outside. It is either made of metal or rubber.  

17. SDL Bars (Simulated Divided Lite Bars)

These ones replaced the traditional muntin bars because they are less expensive, easier to manufacture and have greater energy efficiency for modern large door panels. It is installed on the surface of the glass. 

18. Astragal

The astragal is found in large homes with a pair of doors to open. This piece is that vertical structure that runs in between the two doors connecting from the head to the sill. 

19. Muntin bars

To create large glass door panels, muntin bars were used until the 19th century. They are expensive, hard to manufacture, and extremely fragile. Through the years, it has been replaced by SDL bars.

20. Grilles

These door pieces are vertical bars which create an illusion of divided sidelights but they are actually removable pieces for easy cleaning. Lower maintenance grilles are now more sought-after. They are called grilles between the glass (GBG). They are installed between the glass panes permanently. 

21. Door Panel

This is the inner slabs that make a door what we know of it. They can be designed ornately, raised, or flattened depending on the polish that we want our doors to have. There are also glass door panels. They can be clear or frosted or have tinted, embossed designs. If you are okay with just wood, an exterior door panel can be added for more flair. 

22. Rail

There are top and bottom rails in every door. Top rails connect both sides of the door together. The top rail is the horizontal piece in the uppermost corner of the door. In hanging barn doors, the top rail keeps the door in a square shape by connecting its vertical slats. 

The bottom rail is that horizontal piece at the bottom held together by vertical stiles. Its function is to hold the entire door’s bottom part. In high-traffic areas, a kick plate is installed along with the bottom rail for protection. 

23. Lock Stile

In painted doors, lock stiles could not be very visible but it is attached to the door to hold the entire thing together. It does its job by joining the middle, top, and bottom rails together. For sliding doors, the lock stile is that vertical piece that holds the middle panels usually forming an ‘x’ or ‘z’. 

24. Stop Moulding

This one functions to align the door panel with the frame. With this, the panels are prevented to swing aimlessly right through the door’s opening. It is a piece attached directly to the door frame. 

25. Hinge

All doors usually have three to four hinges in it. Two are installed on the door itself and the other two are screwed in the jambs. It is that part where the door swings in. The hinge pin holds the hinge and essentially the door together for it to swing in and out. 

26. Bore Hole

When you want a customized door, it is very important for you to know how many bores your door should have. Double boreholes are installed to hold the doorknob and the door bolt. Exterior doors usually need this. Single boreholes, on the other hand, are installed mostly in interior doors to only hold the doorknob. 

27. Mullion

This is the part of the door which divides it into four equal, vertical sections. There is a first and second mullion. The first mullion is on the top section and it interlocks with the top lock rail as it runs with the top rail. The second mullion is on the bottom section running from the bottom lock rail and intersection with the bottom rail. 

Lockset or hardware

door lockset

We talked about the casing as like a picture frame and the door slab as the picture. In this case, the lockset can be likened to the painter’s signature. The design and type of your door would determine the lockset that you need. 

Sliding doors need sliding door hardware composed of a sliding door handle and mounting and rolling pieces to hold the door together. Others would only need a door handle like exterior and interior doors. They come in many designs and textures like matte, stainless steel, chrome, or oil-rubbed bronze or brass.

Related: 11+ Different Types Of Sliding Glass Door Locks

28. Key cylinder

It is also called the lock body in which the key is inserted to open or close the door. 

29. Mortise Plates

This one is a protection reinforcement that adds to the strength of the deadbolts, door panels, and latches which function to avoid breaking-in and forced entry. 

30. Deadbolt

This is the one that keeps the door locked. When the key is turned, the deadbolt will be pushed down to the mortice. When it reaches that hole, no one can easily break-in. 

31. Latch

This one is basically the part of the door that keeps the door closed. So once you push the knob down, the latch will be pulled and opens the door. 

32. Handle

door handles

This is the knob used to unbolt the latch for opening and closing the door. The three most common types of door handles are entry handles working on cylinder keyholes, bed and bath handle with an interior push lock button and passage handles that come without a locking system. 

33. Escutcheon

This one is a decorative plate installed in the handles, deadbolts, and thumb turn. They are specifically installed for protecting the door panels from dents and scratches.  

34. Housing and Linkage

This one is found in sliding doors most of the time. It is kept in a metal or aluminum housing where the link retains the door in a latched or unlatched position every time you swing it out or in. 

35. Thumb turn

This one works with a deadbolt on the interior side and a key cylinder on the exterior side. So basically, you unlock a deadbolt by turning the thumb turn from the inside and through a key from the outside. 

36. Strike Plates

This one functions to cover the door jamb area. It is the one that receives the latch and the deadbolt lock. Its function is to protect the door jamb when it is repeatedly used while the door is locked and the latch keeps inserting itself on the jamb. Most importantly, having strike plates proof your home from break-ins. Door jambs without strike plates can be easily broken with force.  

37. Keyhole

As the term implies, the keyhole is where you push in the lock. What is interesting about this is that there is a whole range of keyhole designs to choose from. There is the cylinder lock which unbolts the door through a rotating hole and then there is the multi-point lock which is composed of several lock points in just one door handle. 

38. Spring bolt

Aside from the deadbolt, there is another type of latch called the spring bolt. It is held together by a spring clip which opens the door when it is compressed and locks the door when it is released from the compression. 

Parts of a sliding door

sliding door

Interlocking meeting rail

It is the point at which the two glass panels of a sliding door meet when the door is closed. 

Operable panel

This is the glass panel in a sliding door enclosed in either a steel or metal frame. 

Insulated glass

This one is made by combining two or more glass panels inserted inside the sliding door frame. It is polished with either krypton or argon for better heat insulation. 

Rails or tracks

These are slim structures located on the top and below the door sections in which the sliding door smoothly rolls into for closing and opening. 


This one is located at the sliding door’s bottom section. They are the reason why your sliding door well, slides. 


These are the top brackets where the top section of the sliding door is attached. They are large enough to conceal the top tracks or rails. 


This one is a protective piece usually made of hard rubber, installed at both ends of the track. It functions to block the rollers from jerking or high-impact closing. 

Related: How Much Does a Door Cost? (By Style, Material, Size)


parts of a door and frame

As far as the things we have covered here are concerned, there is more to a door than just the structure that opens and closes for us to enter or secure our homes. The typical door already has more than twenty pieces on it. There will be other pieces for patio doors, French doors, and sliding doors. 

With all of these, you have to understand these individual pieces if you want to have the best design for your door, especially that there are ornate pieces that you can totally customize for more character.