Door Jambs: What You Need To Know

A door jamb is an essential component of any door frame that serves as a support structure and facilitates the proper functioning of a door. As you’re shopping for doors or looking to install one yourself, it’s important to know the different terms and what they mean. A door jamb is a vital part of the door, and it surprisingly provides lots of benefits for your home. 


Infographic pointing out a door jamb on an image of a door.

Essentially, a door jamb is a vertical section of a door frame that forms the perimeter of the door opening. The jamb is installed perpendicular to the wall and is fixed to the rough framing of the wall, providing a stable and secure foundation for the door. Door jambs come in different materials, including wood, vinyl, aluminum, and composite materials such as fiberglass. However, the choice of the jamb material may depend on factors such as the weather conditions, cost, and the door type.  

Two types of door jambs exist: pre-hung and split. A pre-hung door jamb is a complete unit that includes the door, the frame, and the hinges, and it is typically used for new construction or complete replacements. A split jamb, on the other hand, is used for renovations or replacements of an existing frame. The split jamb has two separate vertical sections that are joined together with the help of the hinges. 

Components of a Door Jamb 

  • Casing: This is the decorative molding that frames the door and helps to conceal the gap between the wall and the jamb. 
  • Hinge Mortises: These are the recesses or cutouts in the jamb that hold the hinges, allowing the door to swing open and closed. 
  • Strike Plate Mortise: This is a recessed area in the jamb that holds the strike plate, which is the metal plate that the latch or bolt of the door lock engages with when the door is closed. 
  • Stop: This is the strip of wood that prevents the door from swinging through the opening and hitting the wall. The stop can also be adjusted to control how far the door can open. 
  • Threshold: This is the bottom part of the door jamb that creates a seal between the interior and exterior spaces and provides a smooth transition between the floors on either side of the door. 

Functions of a Door Jamb 

  • Structural Support: The door jamb provides support to the door frame and helps to distribute the weight of the door evenly. 
  • Security: Door jambs hold the door in place and prevent it from being forced open. The strike plate also provides a secure point of attachment for the door lock. 
  • Aesthetic Appeal: The casing and stop molding on the jamb can be customized to enhance the appearance of the door and complement the interior design of the room. 
  • Energy Efficiency: A properly installed and sealed door jamb can help to prevent air leaks and reduce energy loss, leading to lower energy bills. 

A door jamb is an essential component of any door frame that serves multiple functions, including structural support, security, aesthetic appeal, and energy efficiency. It is crucial to choose the right type of jamb and material based on the door type, weather conditions, and cost. Proper installation of a door jamb is essential for optimal performance and longevity. Both choosing the right type of jamb and installing it properly can be ensured when you hire a trusted door replacement company.


A black entry door on a grey house.If you’re looking for expert installers for your door replacement project, West Shore Home® is the right fit for the job. We have a variety of door styles and tons of benefits when you choose us:


  • Signet Fiberglass
  • Legacy Steel
  • Heritage Fiberglass

Features & Benefits

  • Safety & Durability
  • Decorative Glass Options
  • Customized Interior/Exterior
  • Energy Efficient
  • One-Day Installation
  • 10/15-Year Finish Warranty

Every door installed by our team is customized to the highest standards for homeowners. Unlike consumer-grade doors, our professional class doors are customized to your exact measurements for a better fit and a more secure and energy efficient door. Contact us today to set up a door consultation and find the right door for you!