Interior door installation can be challenging, it involves precise measurements and some carpentry. It might be a good idea to work with a professional when you do this. However, if you have the skills, tools, and time, here are the steps to take to add a pre-hung door to your house.

How to Install a Prehung Door in 17 Steps

1. Use a level to find a level spot on the rough opening. Mark spots on both sides of opening with a pencil.
2. Measure down to the floor on the hinge side using measuring tape, and note the measurement.
3. Measure down to the floor on the striker side, and note the measurement.
4. Hook the measuring tape on the bottom of the door on the hinge side, then measure and mark the height noted earlier.
5. Measure from your mark to the top of the header, then measure that same distance on the striker side to ensure the header will be level.
6. Hook the measuring tape under the striker-side jamb and measure up. The difference between the measurement from the rough opening to the mark on the doorjamb is the amount that will need to be cut out of the jamb (depending on the door, one or both jambs may need to be cut).
7. Use a circular saw to cut the jamb(s) to the desired lengths.
8. Use a level to ensure the rough opening is plumb on the hinge side. If not, nail an appropriate number of shims into the rough opening to make it plumb.
9. Move the door in place and keep it flush with the outer wall.
10. Pre-drill a hole and drive in a screw at the top on the hinge side.
11. Check the jamb to see if it is plumb using a level.
12. Finish screwing in the hinge-side jamb using a driver.
13. Line up the two reference lines on the striker-side jamb.
14. Use shims down the hinge-side jamb to level it off, and drive in screws with a driver.
15. Break off the shims.
16. Put on trim using a nail gun or hammer.
17. Install door-knob hardware.

Tools and Materials