How To Install a New Interior Door Like a Pro

Apr 22nd 2022

How To Install a New Interior Door Like a Pro

Need a new interior door for your home, but not sure how to install it? Don't panic. Installing a door is easier than it sounds. If you want to know how to install a new interior door like a pro, we go over all the details you need to know in this prehung and slab door installation guide.

What Kind of Door Do You Have?

There are two kinds of doors to choose from: prehung doors and slab doors. The distinction between the two has a huge impact on the installation process. Prehung doors are door slabs already hung in the frame and pre-cut for the knobs and the strike plate. Slab doors are doors that don't come with frames or hinges pre-attached. Prehung is an ideal option if you want to replace the door and the frame for an all-around new and fresh appearance. Slab, on the other hand, is for those who just need to replace the door slab. The installation process for prehung and slab doors differs. Below, we go over steps for installing both.

Installing a Prehung Door

Are you preparing to install a prehung door? Here's what you need to know.

Remove Original Door

If you're replacing an existing door, you need to remove that door before you can put a new one in its place. To remove your current door, follow these instructions. Use a screwdriver and hammer to remove the hinge pins. Once removed, you can separate the slab from the frame. Next, remove the hinge and strike plates from the frame. Finally, using a rigid putty knife, loosen and pry the trim off the wall.


Next, you need to measure the wall opening to determine the door size you need. For a prehung door, measure the width height, and the depth of the rough opening—the gap in the wall left behind after fully removing the door and frame. Use these measurements to find a door that will fit.


With your new door in hand, you can start the installation. Start by sliding the prehung door into the rough opening until the jamb is flush with the wall. Before you move on to the next step, make sure your door is positioned upright and opens the correct way.

Next, take a level and use it to check if the door is straight. You can use shims to tinker with the level and ensure the plumb is jamb. Slip shims under the side jamb until the head jamb is level, and then shim between the side jambs and studs. Move over to the hinge side of the door and shim between the hinges and studs, then move to the latch side and shim in the same areas.

With that done, you can grab your trusty drill. Take two #8 finishing nails and drive them through the shims and into the studs of the frame. Drive two nails into each shim half an inch apart and an inch from each edge of the jamb. Next, nail the trim to the jamb and the studs. Take #6 finishing nails and drive them into the trim and studs 16 inches apart. If there are any exposed shims, trim them by scoring with a knife. Rinse and repeat on the other side of the door.

Almost done. All that's left is to attach the backplates, lockset, strike plate, and knobs. Once you're done with that, you can stand back and admire your new door: the installation is complete!

Installing a Slab Door

Have a slab door? You'll be happy to hear that it isn't too different from installing a prehung door. Look below for instructions.

Remove the Original Door

For a slab door, you want to keep the frame intact and just remove the slab. To remove the slab, use a screwdriver and hammer to remove the hinge pins and then slide the door out from the frame. It's that easy.


Measuring for a slab door is a bit different than measuring for a prehung door. To measure for a slab door, start by taking your tape measure and placing the end of the tool in the top corner of the door opening. In this case, you want to measure the gap inside the frame rather than the rough opening.

Take the height first. Pull the tape measure down and stop 1/8th of an inch above the ground. If you have carpet, stop 3/4th of an inch above the ground instead. This keeps the door from catching on the carpet fibers. Then, measure the width of the opening, leaving a 1/16-inch clearance on both sides. Reference these measurements when choosing a slab.

There's a chance your new door will be too large for the frame. If this happens, no worries—you can simply trim your new door down to the correct size.


Got your door? It's installation time! We'll begin by attaching the door hardware. Use a measuring tape to measure the location of the hinges on the doorframe and then mark where they should go on the new slab.

Place one of the hinges in the marked area and use a utility knife to cut a line around the edge. Measure the depth of the hinge and then remove it. Pick your utility knife back up and use it to create the mortise, the shallow indentation where you set the hinge. Place the hinge in the mortise and fasten it with hinge screws. Repeat for all other hinges. Then, install the knobs on the door.

Finally, you can hang your door. Position the door and attach the hinges to the frame with screws. Once attached, open and close the door a few times to make sure it works correctly. If it works like a charm, congratulations—you're done!

Those are our tips on how to install a new interior door like a pro. Keep in mind that all doors are different; the installation instructions for your particular door may differ, so see if your new door comes with specific instructions before following these general rules.

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How To Install a New Interior Door Like a Pro