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 fool-proof 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 lock set for the door even though we won’t cover the installation in this article.
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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.
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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.
Check Your Rough Opening Carefully 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.
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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.
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.
