If you’re going to install your own interior door, our door experts recommend purchasing a pre-hung door. This kind of door is the easiest door to install, as it comes already mounted to a new door jamb with the hinges installed and the lockset and deadbolt holes already drilled. Here’s what you’ll need to get the job done:

Before you begin, make sure the top and bottom of your door is painted (which should be done at the factory). This prevents warping. Because your door already has a jamb, you won’t have to worry about measuring and installing one. However, you’ll have to make sure that the jamb is square within the doorway.

1. Use a large level to see how plumb the doorway is common to the hinge-side of the door.
2. Use wood shims to make sure it’s level and tack them to the door jamb at the same height as the door hinges.
3. Slide the door up against the shims and measure the gap. Both the side gap and the gap at the top should be 1/8″. You don’t have to worry about the gap on the door-knob side of the door until last.
4. Use finishing nails to attach the hinge jamb to the doorway by driving them through the shims. However, leave about ½” gap between the nail and the wood in case you need to make adjustments.
5. Measure the door-knob side gap between the jamb and the doorway and insert a shim near the top of the door until the two are flush.
6. Place another shim about six inches above the lock strip until the jamb and doorway are flush, then do the same 6 inches below the lock strip.
7. Once you make sure the gap is the same all the way around your door, nail your shims in place and cut off any excess.
8. Open and close the door to make sure the movements are smooth.
9. After that, you can install the other half of your jamb if you’re working with a split jamb door.
10. Finally, install your door knob.