Building a Door Jamb

In order to build a door jamb, you need to take into consideration several criteria such as the size of the entrance door, the size of its opening, the material and width used to build the entrance of the door jamb, and also the thickness of the wall. Below are some of the steps that you can do in order to go through the process of building a door jamb.

What you need:

  1. 2 pieces of lumber (1-by-6-by-96-inch)
  2. 1 piece of lumber (1-by-6-by-48-inch)
  3. Table saw
  4. Electric miter saw
  5. Router w/straight bit
  6. Carpenter\’s square
  7. Door stop material
  8. Variable speed drill
  9. 1/16-inch drill bit
  10. Phillips head screw tip
  11. Hammer
  12. 4d finish nails
  13. 3-inch drywall screws
  14. Nail set


  1. First of all, you have to ensure that you measure the width wall correctly. You need to set the table saw fence at the width of the wall at the door opening and also include the inside wall material along with the outside material. Then, break the three pieces of the 1-by-6 lumber according to the width that you have measured and if the wall thickness is greater than 5½-inch, it is recommended that you use the 1-by-8-inch material instead.
  2. The next step to do is to measure the top width of the door opening before marking the 48-inch lumber and cutting it so that it can fit with the electric miter saw. Bear in mind that the standard height of an entrance door is at least in the range of up to 78-5/8-inch, meaning that the door jamb sides need to be at least 80-inch in width for allowing you to fix the threshold and the door sweeper.
  3. Next, you have to mark the two pieces of 96-inch lumber at 80-inch and then cutting them using the electric miter saw. After that, measure down starting from the top of the door to the top of the top hinge before measuring down from the top of the side where the door will hinge and add about 1/8-inch more and mark it. Then, you need to place the corresponding hinge on the mark and trace around the shape of the hinge using a pencil.
  4. When you have finished doing Step 3, you need to measure the position of the jamb itself where you need to measure from the bottom of the top hinge to the top of the center hinge and also mark the jamb\’s position. After that, place the corresponding hinge on the mark and trace around the shape similar to what you have done in Step 3. Then, measure from the bottom of the center hinge to the top of the bottom hinge and also mark it.
  5. Proceed the exercise of cutting the hinge\’s shapes using a router and make sure that the depth of the cut will match the thickness of the door\’s hinge. Then, you have to install the hinge plates inside the cutouts.
  6. After that, mark the center of the top piece of the entrance door jamb before measuring the width of the door plus adding a further ¼-inch to the measurement. You need to divide the measurement by two and again measure from the center mark in both directions before making a mark. This will be the area where the side piece of the door jamb is secured to the top piece. Then, place the carpenter\’s square on the marks and draw lines across the width of the material
  7. Next, you need to mark a piece of the door stop material where you can use the same measurement derived from the previous Step and then, cut the door stop to be able to have 45-degree angles on both ends.
  8. When you have finished Step 1 to Step 7, you have to proceed with the assembly and installation exercise. Firstly, measure the thickness of the door and add 1/8-inch more to the measurement. Then, you have to mark the three entrance door jamb pieces from the inside edge of the jamb where the door-stop material will be secured. The top pieces of the door stop material need to be applied with glue and place it on the line before ensuring it to be secured using 2d finish nails. To make this process easier, you can also use a 1/16-inch drill bit for drilling pilot holes.
  9. Then, you need to cut two pieces of the door stop material according to the length of the sides of the jamb. Each of the angles also must be cut with a 45-degree angle enabling them to meet with the angle of the top piece. After that, apply some glue to the back of the pieces for securing them to the jamb similar to Step 3.
  10. To make it secure, you need to use 4d finish nails so that the sides of the door jamb to the top of the door jamb is fit together. Then, you have to set the door jamb in the hole for the entrance door and also place door shims in between the jamb and the studs (optional and only where it is needed) and ensure that the jamb is secured to the entrance door opening. After that, secure the hinge\’s side and place the carpenter\’s level against it to make sure that it is plumb.
  11. In order to ensure that the fixture is level, you need to place the level on the top piece. You can do some adjustment by lifting the remaining side of the jamb also secure the top along with the remaining side by using 4d finish nails.
  12. Finally, you have to install the door by simply slipping the hinge plates on the door together with the one on the jamb and tapping the hinge pin so that it is in place. After that, install the door knob hardware and also make sure that you trim the door with the door casing.

Image Credit:
Fickr CC

Additional Reading:
Build Like a Pro Windows and Doors: Expert Advice from Start to Finish (Taunton\’s Build Like a Pro)

Building Doors & Gates: Instructions, Techniques and over 100 Designs