How to Install or Replace a Door Frame

new door frame under construction
  • 4 hours
  • Intermediate
  • 500
What You'll Need
Pre-assembled door with frame
Pry bar
Trim pry bar
Plumb line
Spirit level
Straight edge
Measuring Tape
Finishing hammer
Drill (preferably cordless)
Holes saws
Spade bits
Screwdriver bits
What You'll Need
Pre-assembled door with frame
Pry bar
Trim pry bar
Plumb line
Spirit level
Straight edge
Measuring Tape
Finishing hammer
Drill (preferably cordless)
Holes saws
Spade bits
Screwdriver bits

Replacing a complete door with its frame for the first time might seem to be quite a challenge, but surprisingly enough, you might end up finding the project to be much easier than first anticipated. With a few basic tools to begin with, you’ll also save a couple of hundred dollars that a professional would charge to do it.

With the right tools but also the proper knowledge and terminology assigned to every distinctive component making up your door assembly, you’ll be able to make a more accurate selection of the exact parts that you asked for or surprise a salesman while holding a conversation where he cannot wait to start throwing a whole bunch of technical terms at you.

So taking 10 minutes now to acquire some necessary knowledge will spare you much more time at the hardware store describing what it is that you’re looking for, or returning supplies once they’re delivered, realizing you got the wrong parts.

Types of Swing Doors and Their Frames

Every residential home has exterior doors that are most likely to be inswing. The inside of homes can also be accommodated with interior doors used to separate individual rooms in the house, thus permitting or limiting their access when required.

Since they’re not required to withstand heavy security or to stand up against exterior weather, you’ll usually find them built with less substantial material and consequently much lighter to handle and work with than exterior doors.

In any type or form, doors are basically large panels hung vertically to a larger frame by means of hinges, so they can swing open to provide you with a large opening in the wall. When they open inside of the room, they are referred to as an “inswing,” and if they open outside and away from the inside of the room, they are said to be “outswing”.

Terminology of a Basic Door

The Door Frame

The collection of all the components forming the perimeter of the door frame assembly is the door frame. In its most basic form, it consists of 2 side jambs and a head jamb. An exterior door frame will also include a sill as an integral component of the assembly.

More elaborate frames, however, such as the ones built with transoms, sidelights, or even frames built for double doors, would also include any mullion bars that are used to separate multiple panels within the frame assembly.

Residential door frames are most commonly made of wood, aluminum, fiberglass, or of a composite material. They can be purchased primed and ready to paint or already painted with a factory finish.

The Side Jambs

Side jambs are the 2 vertical components forming the outside perimeter of the frame, where the hinges are used at one side, and the striker plate is installed on the other side.

The Head Jamb

This is an integral component of the door frame assembly running horizontally across the full width of the frame and joining the two side jambs at the top of the door frame.

Casing Trims and Brick Moldings- These are designed to conceal the gap between the door or the window frame and the finished wall surface around it. The term “casing” is used to describe the trim moldings on the inside walls, while “brick molding” is an exterior casing trim made thicker in order to provide a better edge for the brick or cladding surrounding it.

The sill- Sills are components used almost strictly on exterior doors and serve to facilitate fastening the door frame to the floor and also to provide the means for creating a better weather seal. The sill is installed at the bottom of the frame and joins the hinge jamb and the striker jamb together, providing increased rigidity and stability to the door assembly.

Margins- Also known as rebates, the margins are the spaces purposely created between the door frame and the door panel(s) and are critical for proper and unobstructed door panel movements. While preventing positive contact and friction between the two wood surfaces, they are thin enough to maintain structural stability. They are commonly identified as the hinge margin, the strike margin, the header or top margin, and the bottom or sweep margin.

The stop moldings- The doorstops are installed on the inside face of the side jambs and the top jamb. They’re placed at the same distance from the edge as the thickness of the door panel so that the panel comes perfectly even with that edge of the door frame. It, therefore, keeps the panel from swinging in too far in when closing the door.

Knowing the proper terminology will help you communicate your specific needs when you seek assistance for your specific door problem or components.

Assessing Your Door Frame Project

man in hard hat measuring door frame

1. Size the Opening

Before selecting the right size of door that you need, you’ll have to determine the overall plumb and level size of the door opening. The best way to do this is by removing the casing trim from the inside wall. if you’re planning on salvaging your molding and using them on the new door there are a couple of options you can look at.


Where there were one or more coatings of paint applied since the door was installed, it would be a good practice to use a utility knife and cut through the paint along the inside corner formed where the trim meets with the wallboard. This will prevent paint from peeling off the wall.


With the use of a trim puller or a trim pry bar, tap the flat blade of the puller to insert it behind the trim at the height of each and every nail while pulling slightly and gradually away from the wall.

This should be done by pulling out no more than a 1/4-inch at a time and going from one nail to the next until the whole length of molding is slightly pulled out, then repeating the procedure until it comes off. Do this for both side casings and head casing.


With all 3 pieces of casing trim removed, you are now looking at the hidden part of the door frame and the framing of the rough door opening. There should be a gap in between and around the perimeter of the door opening.

Although you probably can’t see it all, the rough door opening is constructed of two-king studding, one on each side running vertically between the floor plate and the top plate of the wall.

Nailed to each king stud on the inside of the opening, you have a trimming stud onto which a header running between the two king studs is resting securely. These four studs ensure that the door frame will be solidly secured in place.

2. Check the Plumb and Square of the Rough Opening

The exact size of the rough opening will largely depend on its squareness. This can be determined with the use of a 4-foot level.


Bring your spirit level up close to the rough opening header. Maintaining it leveled and up against the wall, slide your level up or down to get the lowest corner of the header lining up with the level. Trace a mark on the wall at the other extremity where the header should be. That provides you with the rough opening’s finished height.


Even if a plumb line is better suited for this next step, a 4-foot spirit level in conjunction with a long straight edge can be used just as easily by bringing the straight edge close to the edge of the rough opening and leveling it against the wall.

If the top of the opening leans in, trace a mark on the floor and at the header to mark the spot. If it leans out, then trace a mark on the wall at that position to indicate where the trimming stud “should be” and where you’ll need to measure from for the width of the rough opening.


Repeat the previous step for the opposite side of the rough opening.


Measure between the 2 marks, between a mark and the opposite trimming stud, or simply between the trimming studs if everything is plumb, for your rough door opening width.


The rough opening height is then measured between the lowest spot on the floor to the lowest end of the header. This means that if the floor isn’t level, you might have to trim one jamb and the bottom of the door to fit properly, but it is better than getting an obvious and wide gap at the bottom.

3. Determine the Tolerances around the Jambs, Header, and Floor

With the overall maximum sizes of your door opening, you now have to determine the ideal width and height at which to buy your door. When installing a door frame, there should be a gap around the perimeter of at least 1/2 inch.

This gap lets you install spacers of varying thicknesses to give the door its final adjustments making sure that it is perfectly plumb and level on both axes.

That particular gap should ideally be between 1/2 to 3/4 inches making the total width of the door between 1 to 1-1/2 inches narrower than the rough opening. The gap is then used to insert your wedge-type spacers to center and temporarily secure the door frame in place, adequately plumb and level.

On an exterior door installation, the remaining gaps will be filled with expansion foam to seal it from outside air infiltration.

4. Get Your Door Assembly and Other Supplies Ready

When you get to your hardware store and start discussing your needs and their options on available doors, along with what they have available in stock and on special sales, you can then decide on the final finished size of your door. A little compromise can bring you a long way when considering savings and delivery delays.

You will also need accessories such as spacers, wedges, stoppers, weather strips, door handles and lock set, nails, screws, etc... You should also have your hammer, a cordless drill and various screw-driving bits, hand screwdrivers, and a pry-bar, just to name a few depending on your preferences for that type of work.

If you have a reciprocal saw, it could be a good idea to bring it along with a fine-tooth metal cutting blade.

A reciprocal saw blade can be inserted in between the door frame jambs and the trim studs in order to effortlessly cut the nails and screws securing the door frame to the opening.

Removing the Old Door

hand unscrewing door hinges

5. Remove the Door Panel from the Frame

Now that you have all your tools handy, remove the door panel itself from the door frame. This will make the frame much lighter to handle.

6. Remove the Old Door Frame

With all the casing trims already removed in Step 1, place the metal cutting blade of your reciprocal saw inside the gap and slide it along the whole length of each jamb. Cut every nail and screw that comes across the blade. If there is expandable foam or wedges in the way, just activate the saw, cut through it, and keep moving along.

If you don’t have a reciprocal saw, you’ll have to remove the stoppers. hinge plates, and the striker concealing every nail and screw that might have been used to secure the frame. A trim puller should be used to remove the stoppers with minimal damage.

With all these components removed, you can now extract all the nails and screws with your screwdrivers, your nail puller, and your hammer.

Installing the New Door

7. Insert the New Door Frame into the Wall

You can now insert the new door assembly into the wall opening—this could require extra assistance. Once inside the opening, the door panel can be opened at 90° to add support, maintaining the door in an approximately vertical position—you can fill in between the panel and the floor to bring it to a better positioning.

8. Adjusting The Door’s Level


For an exterior door, once the door is temporarily set up inside its opening, place a 2-foot spirit level on the door sill prior to nailing, tacking, or screwing any fastener anywhere around its perimeter. Wedge spacers can then be inserted wherever they’re needed to bring the sill perfectly leveled.


For an interior door, place the 2-foot level up against the door frame header, and have someone slide wedge spacers under the lower side jamb to bring up the header at its lower extremity.

Measure the gap that the spacers added between the jamb and the floor and trim that much off the opposite side jamb so that when installed, both jambs rest on the floor. In more extreme cases, the door panel might even have to be trimmed at the bottom to ensure a better fit without any friction against the floor.

9. Set the Door Frame in Position

With your door assembly now standing level at the sill and/or at the header, consider the placement of the marks made in step 2.2 and slide the hinge jamb up against the trimming stud at whichever end the mark meets the trimming stud—depending which way it’s leaning—and after placing it even with the finished wall, screw it to the stud.

Note 1

Since an exterior door comes with the brick molding already attached to it, you can simply pull the door frame in until the brick molding sits firmly against the outside wall surface before securing it at the 1st corner.

Note 2

All nails, screws, and other fasteners should be placed where a stopper molding, a hinge plate, or a striker plate will conceal them.

Note 3

You should make sure to occasionally open and close the door while doing the installation to make sure that you don’t end up with surprises at the end and that the margins between the panel and the frame remain constant around its perimeter.

You can now secure the other extremity of the hinge jamb after lining it up with the mark made in step 2.2 and filling the gap with spacers to keep it plumb.

Once the hinge jamb is secured at both ends, you can move to the other jamb and secure it in the same manner, doing the top first after putting in the necessary spacers at the top, then finishing with the bottom in the same way, making sure that one side remains flush with the wall next to it (or up to the brick molding).

10. Secure the Door Frame Permanently

Returning to the hinge jamb, you can now finish filling the gap behind it at every hinge and also in the middle when the door only has two hinges. While inserting the fillers, keep checking with your spirit level to make sure they don’t push too much against the jamb, making it bow. All fasteners should be placed behind stoppers and hinges.

Return to the striker jamb and use fillers starting behind the striker plate and checking frequently with the level to secure the jamb in its proper place. Keep securing using more fillers halfway down to the floor and halfway up to the header stabilizing it in five secured spots.

The door sill can now be secured using preferably #10 screws at four or five different locations, and the header can be secured in the same manner with #8 screws in 2 or 3 spots to complete the installation.

11. Finish Up

It is now time to install the mechanism, the striker plate, and the deadbolts if needed. If the panel is not already bored to receive the handles, you will need a proper size hole saws and a drill to install the mechanism.

If you decide to install a deadbolt, you will also need a hole saw to cut the opening. Always follow the instruction provided with the hardware to install them properly.

The stoppers and weatherstrips can finally be installed. They come in various forms and designs, so you should follow the instructions that come with them and always install them with the door panel closed to provide them with the proper clearances and a good seal all around.

With all that completed, you can now get your miter saw and install your casing trims around the door to properly conceal the gaps and studs.

If you'd like to learn more about a similar subject, check out our article about building French doors.