How to Replace an Interior Door

Follow these steps and get perfect results

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Video: How to Hang a Door

Travis Larson, an editor for The Family Handyman, shows you how to remove a door and hang a new one or rehang the old one.

Step 1: Overview

Hanging a door correctly is one of the most satisfying jobs in the home improvement world, but it's often the most challenging. Unless it's installed correctly, your door can have uneven gaps along the jamb, or it can bind or not even latch.

In this article, we'll show you foolproof tips and techniques that'll give you great results every time. All you need are simple carpentry tools and some basic home improvement skills and tools to easily master the techniques. Allow about an hour and a half for your first door, and once you get the hang of it, your next door will go in twice as fast.

When you buy your door, pick up a package of wood shims and 4d, 6d and 8d finish nails. Also get a straight 7-ft. 2x4 and cut another 2x4 the width of your opening (Photo 1) that are both straight as you sight down the edge. Since installing trim is part of the door installation, purchase some matching door trim and be sure you've got a miter saw to cut it. You'll also need to pick up a lockset for the door even though we won't cover the installation in this article.

Pro Tips for Hanging Doors

  1. An accurate level is crucial for a good installation. Check it by laying it on a flat surface. Memorize the bubble's position. Then flip the level end for end and check the bubble. If the bubble doesn't settle in the exact spot, find an accurate level.
  2. Check the length of your prehung door jambs. They may be longer than you need. You may have to trim both sides to minimize the space under the door. In most cases, the door should clear the floor by 1/2 in.
  3. If you're setting your door into adjoining rooms that'll be carpeted later, you can hold both jamb sides 3/8 in. above the floor and avoid having to trim your doors.
  4. Use blocks to level jamb bottoms. If you’re installing a door on an unfinished floor and need space under the jambs for carpet, just rest the jambs on temporary blocks while you’re hanging the door. Adjust the size of the blocks so the bottoms of the jambs are on a level plane. Leaves a space of anywhere from 3/8 in. to 5/8 in. under the jambs, depending on the thickness of the carpet and pad.
  5. Check the plug. Make sure the plug that holds the door slab in place is the type that can be removed after the door is installed. If it’s not, sometimes you can cut off the plastic strap and insert the plug back in through the doorknob hole. It’s difficult to move the door when the slab is flopping all over the place, but it’s worse to install a door that won’t open.
  6. It’s not always necessary to use shims on the top doorjamb—the casing will hold it in place. And on new homes and additions, walls can compress as they settle and push down on the top shims, causing the jamb to bow down. Only shim the top jamb if you’re working with a 3-ft.-wide door, and the top jamb arrives bowed from the factory.

Level the floor

The most critical step of any door installation is making sure the bottom of each doorjamb is at the proper height. If you’re installing a door on a finished floor and the floor isn’t level, you’ll have to cut a little off the bottom of one of the jambs. If the floor slopes slightly and the jamb isn't trimmed to compensate, your latch won't line up. You must check the floor with an accurate level as shown in Photos 1 and 2.

Step 2: Check Your Rough Opening Carefully and Prepare the Door Before Starting

In this article, we'll focus on installing standard prehung doors. These have a door jamb that's 4-9/16 in. wide and are made to fit into a 2x4 wall that's 4-1/2 in. thick. This gives just enough of a fudge factor to have the jamb a bit proud of the wall surface on each side and to make up for any irregularities in the trimmer studs of the walls. Most openings will be about 82 in. high for standard doors, so that's what we'll focus on. If your wall is thicker or your opening is shorter, you'll have other concerns we won't cover here.

Before you order your door, check the width of your opening. It should be 2 to 2-1/2 in. wider than the door. This extra space gives you room to fit the jambs and the shims into the opening to hang the door. If your rough opening is 32 in., get a 30-in. prehung door. Also check the vertical sides of the rough opening to make sure they're reasonably plumb. Openings that have a trimmer stud out of plumb more than 3/8 in. from top to bottom will make it nearly impossible to install the door. It would be somewhat like trying to put a rectangle into a parallelogram. Small variations from plumb are quite common, however. Checking both sides and getting familiar with any problems with the opening will give you an idea of how much and where to shim the jambs later.

Most installation problems occur because the floor isn't level under the doorway. If the floor slopes slightly and the jamb isn't trimmed to compensate, your latch won't line up. You must check the floor with an accurate level as shown in Photo 1.

For complete directions, just follow our step-by-step photos and instructions.

How Do You Fit the Jamb to Floors of Different Heights?

Cut a 1-ft. long strip of 1/4-in. plywood the same width as your door jamb. Drop it to the high side of the floor, tack it in place, set your scribe and mark the contour of the floor onto the plywood. Remove the plywood, cut the shape with a jigsaw and transfer the shape to the bottom of the jamb. Cut along your mark with a jigsaw. Do this for each side of the door. If your transition is more than 1/2 in., you may need to trim the bottom of the door as well.

Scribing the door jamb

Set the door in place

This is where things get serious. Nobody pays much attention to doors that work the way they should. They open—they close. But doors that were improperly installed can bind, swing open by themselves or rattle in the breeze when they’re closed. Follow these steps for a perfect door installation job.

Secure the door in place

When the door is in position, nail it into place. Follow these steps for foolproof installation.