BLOG/ How to Replace an Interior Door

There are a number of reasons that may lead you to replace an interior door. If the door is damaged beyond repair, or warped, it must be replaced out of necessity. Your doors may well just be outdated and you want to radically redecorate.

Whatever the reason, we are here to tell you that replacing an interior door is a simple project you can take care of on your own! Follow these simple steps to give your house a little pick-me-up. 

1 Select a replacement door

Before you remove any interior doors, you will want to have a replacement lined up and ready to go. There are so many styles and designs in the door world.

Beyond style, you will want to decide whether or not you want a hollow core door, or a solid-core door. Check out our blog article on how to select a wood door to help you make the right decision. 

Don’t forget to measure your pre-existing door to ensure the new door is the right fit! You will need to measure the width and height of the door. The thickness of interior doors is standardized at 1 ⅜ inches.

Unless you are also replacing the jam, you will just be looking for a slab door. Prehung doors come surrounded by a jamb and everything needed to start fresh. 

Typically, doors come in only a couple heights, with 80 inches being the standard. It is the width that will vary widely. An interior door should be ⅛ inch from the jamb on the top and sides of the door, and ⅝ inch from the floor.

2 Remove the old door

Removing the old door is pretty simple and there are two basic ways you can do this. The first involves removing the hinge pins.

To prevent the door from falling on you as you work, always start at the bottom hinge and work your way up. It is best if someone is around to support the door as you get closer to removing that top pin.

If the hinges seem stuck, you can use a screwdriver inserted into the bottom of hinge. Gently tap the screw driver with a hammer until the pin comes loose. 

In the rare case that the pin is welded or fixed to the hinge, you will not be able to remove the pin. Instead, you will have to remove the screws from the hinges on the door, still working from bottom to top. You should simply be able to pull the door off its hinges at this point. 

Remove the door knob and hinges from the old door and put them in a safe place. If you plan to reuse the door knob, play close attention to how it fits together. This is not the time for a puzzle! 

Once all of the hardware has been removed, set the old door aside and start dreaming of what DIY project you can do with an old door, or perhaps where you can donate it to be repurposed.

3 Fitting the new door

Interior doors vary in size. Even after your careful measuring, you will want to verify that the new door will indeed fit into the old jamb. You can do this by laying the old door across a pair of sawhorses and setting the new door on top. Make sure the top ends and door knob holes are perfectly lined up.

If the new door is too big, trace around the old door to mark where the new door must be trimmed. Use a straight edge guide and circular saw to make any necessary cuts. If you need to remove less than 3/16 inch, you will want to use a hand plane instead of a saw. 

Lay the old door back on top of the new door, aligning them so that all four edges are flush.

4 Installing Hardware

First come the hinges. Line up the new door with the old, making sure it is completely flush. Use a combination square to square the old door’s hinge mortises and use a pencil or utility knife to make their location on the new door. 

Line up a combination square with the old door’s hinge mortises and transfer their locations to the new door. Next, you will want to chisel out the hinges. Hold the chisel vertically and tap it with a mallet to outline the hinge mortise.

Only make the mortise as deep as the thickness of the hinge. If you accidentally cut too deep, you can use a thin shim to make up for it. 

Then, hold the chisel at a slightly horizontal angle to prevent it from digging in too deeply. Lightly tap the chisel to diligently chip away the wood. Test the mortises often with the hinge leaf to make sure it will be flush with the door’s edge.

Once you get the perfect fit, set the hinge leaf into the mortise. Use a drill and centering bit to bore pilot holes through the screw holes. Finally, screw the hinge to the door.

Test fit the door to check that it will close properly. While you do this, mark where the strike-plate meets the door. 

Position the template supplied with the lockset on this mark. Then, mark for the doorknob and latch. If reusing the old lockset, take measurements from the old door.

Drill the doorknob face bore with a 2 1/8-inch hole saw. Cut the latch’s edge bore with a 7/8-inch spade bit.

Once all the holes have been made, it is a good time to paint or stain the door. Make sure you coat every surface, including the bottom, top and sides!

When the door is dry, you can screw the latch to the door, then install the doorknobs. The latch plate may also need a thin mortise chiseled out. 

Hold the door in the opening and interlace the hinge knuckles. Once all the hinges are aligned, have a helper insert the hinge pins.

Now you can test the door to see if it swings smoothly and to see if the latch properly engages the strike plate. You may need to reposition the strike plate if it doesn’t quite line up.

And there you have it! You have successfully replaced an interior door.