How to Install an Interior Door

Instructions for Installing an Interior Door

By Mark J. Donovan

Installing an Interior Door is a relatively easy task. First, I recommend buying pre-hung doors with extension jambs. These are interior doors that have the trim already attached. Using Pre-hung doors makes the task of installing interior doors relatively simple.

When unpacking the door you will see that the door can be separated into two pieces. The first section you will want to install is the section that contains the door itself.

Installing Interior Door

Place the door into the opening. The rough opening of the doorway should be about 2-3 inches wider than the door frame that you are installing.

Then put a 1/8th or 1/4″ shim under the door, on the side where the hinges are. This will help in the leveling process.

Put a nail about one foot off the ground on the hinge side. The side that you just shimmed. Do not sink the nail, just in case you have to remove it later when squaring the door.

Then using a level, place it vertically up the side of the interior door frame that has the hinges. Adjust the door so that the level shows the bubble fully centered in between the two lines of the level. While maintaining this level, put a nail into the door frame about a foot from the top. Again on the hinge side of the door.

Now place the level on top of the door frame and adjust the non-hinge side of the door up or down to get the top of the door level. While maintaining the level position put a nail on the top of the frame about 3 inches from the non-hinge side of the door. Do not sink it.

Finally, place the level on the non-hinge side of the door and adjust the frame so that it is level. Put a nail into the top and bottom of this frame. Do not sink it.

Installing Interior Door – Testing Phase

Now try opening and closing the door. It should swing freely and close nicely with about a 1/8 inch gap showing between the door itself and the non-hinge side of the door. If not, you may have to make some minor adjustments. That’s why you don’t want to sink these initial nails.

If the door works smoothly then sink these nails and add 2 more nails to each side. You should also ensure that you have 3 nails across the top.

Planing a Sticking Door

Once this is done, the other half of the door frame (the trim piece for the back side of the door) should slide into the grooves easily of the portion of the door frame that you just installed. Simply sink some nails into this half and you are ready to install the door hardware and interior door trim.

For information on how to install interior door trim, see the “Installing Interior Door Trim” eBook from  The “Installing Interior Door Trim” eBook provides step-by-step instructions on how to install interior door trim. Pictures are included for every key step in the process.

Related Information

Additional Door Resources from

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