Door Anatomy 101

A door is not always just a door; it can be a first impression, or a statement about who you are. Front doors are a great way to boost your curb appeal and really make your home stand out. A front door is also the mouthway of your home and Johnson Brothers can help make it smile. 

Additionally, knowing the anatomy of a door can be helpful when shopping for a new door, upgrading door parts and simplifying the buying process. Before selecting all the different parts and pieces of your new door, you’ll want to decide on a style.

Door Anatomy illustration

Types of Doors

When it comes to styles, there are a plethora of different designs to choose from. Some common door styles include Dutch doors, French doors, bifold doors, sliding doors, pocket doors, barn doors and pivot doors. Once you have style nailed down, you can start shopping for materials, accessories and add-ons. With that being said, let’s take a closer look at the basic anatomy of a door.


Simply put, the slab is the door – the giant piece of wood that swings around the door unit. As the main component of a door, the slab is commonly made of fiberglass, steel or wood but can also be made from aluminum or glass. The slab can really set the tone of your home, so make sure you pick the right look.

The door slab itself generally consists of three elements including the stiles, rails and lock block. The stiles are the vertical pieces of the slab, while the rails are the horizontal pieces. Paneled wood doors have obvious stiles and rails, while other materials like flush wood doors may not have either. Lastly, the lock block is one of the most important aspects of the slab as it is where the door lock is attached.

Now, let’s venture outside of the door slab and talk about the basics of a door unit. Without the unit, a door cannot function as intended. The unit most commonly consists of the sill, the jamb/frame and moulding, but can vary considerably based on style.


The sill is the piece of aluminum that sits on the ground underneath the door and connects the frame from both sides. A good sill is like a gateway which helps protect your interiors from unwanted dirt, debris, bugs and more. The main parts of a sill typically include the deck, cap and substrate.


The jamb or door frame are the three pieces that frame the door, consisting of the two vertical side jambs and the single horizontal piece at the top of the door called the head jamb. Depending on your preference, the jamb can be made of veneered wood, solid wood or composite material, which determines the strength of the frame. 


The moulding is installed around the door frame and can be positioned to conceal unwanted gaps and accentuate the style of your door. While moulding can increase your front door curb appeal, it can also offer protection to the entryway by preventing moisture into the door unit. 

Keep in mind, all doors are designed differently. Your door may include different parts and components all depending on material, style and personal preference. If you’re simply shopping for add ons you may want to brush up on door handles and knobs, hinges, weatherstrips and deadbolt locks.

Door knobs range from privacy and passage knobs to interior mortise knobs/handles. You can also choose from many different types of hinges including butt hinges, overlay hinges, spring-loaded hinges and more. Whether you are shopping for interior or exterior door parts will determine your need for weatherstrips. For information on deadbolts and other locks, check out our blog on door locks.

Again, this is all just basic door anatomy – BUT, much like shopping for anything, being knowledgeable about what you’re looking for makes the hunt easier on both ends. With that being said, make sure to visit Johnson Brothers in Idaho Falls or Boise for all your interior and exterior door needs.