How to Install an Interior Door in Your Home

Installing an interior door can be a rewarding DIY project, but requires careful planning and execution. You can complete this task successfully and enhance the look and functionality of your home with the right tools and instructions.

The process of installing an interior door requires precision from measuring and preparing the opening to hanging the door and finishing the trim. Always follow manufacturer-specific instructions and prioritize safety when taking on any DIY project.

How to Install a Pre-Hung Interior Door

Hanging pre-hung interior doors is possible for those with enough skill and strength to complete the task. When choosing between apre-hung door and a slab door, consider whether you want to change the frame as well as the door itself. If so, a pre-hung door is the best option.

Follow this step-by-step guide to install a pre-hung door:

1. Remove the Existing Door

If you're replacing existing interior doors, follow these steps:

Remove the door: Carefully detach the door from its hinges. Use a screwdriver or electric drill to remove the hinge pins. You can then remove the door from the frame.
Remove the trim: Carefully pry off any trim or molding around the door frame, using a utility knife to score along the edges.
Remove the frame: Use a reciprocating saw to cut through any nails or screws holding the old door frame in place.
Clean the opening: Remove any debris or protruding nails from the opening.

2. Measure the Rough Opening

Before purchasing a pre-hung door, accurately measure the rough opening to ensure a proper fit. The pre-hung doors should be 2-2.5 inches smaller than the actual door dimensions to allow room for the frame.

Measurement Guidelines:

Width: Measure the width at the top, middle, and bottom of the opening.
Height: Measure the height on both sides and in the center.
Thickness: Measure the thickness of the wall, including drywall or plaster. Use the smallest width and height measurements to select the appropriate pre-hung door.

Checking for Plumb and Square

A plumb and square opening is essential for proper door operation. Follow these steps to check:

Floor level: Place a level on the floor in the doorway. Adjust the shims under the hinge side if necessary to ensure the level's bubble is centered.
Wall and trimmer check: Use a level or plumb bob to check the walls and trimmer studs for plumb. Verify that the trimmers are square to the wall using a framing square.
Parallel trimmers: Measure between the trimmers at the top, bottom, and middle of the opening to ensure they are parallel.
Adjustments: If the wall is out of plumb or the trimmers are not square or parallel, you'll need to make adjustments before installing the pre-hung door.

3. Position the Pre-hung Door

Pre-hung doors, especially those made from heavy materials or with solid cores, can be heavy and difficult to maneuver alone. Asking for help is the safest course of action at this point. Here is how to position your pre-hung door: 

Begin by centering the door in the rough opening.  
With your installation partner, align the door so the jamb is flush with the wall. 
Ensure that the handle or doorknob is on the right side and that the door swings inward or outward as intended.

4. Level the Door and Fix the Jamb to the Rough Opening 

This stage requires several steps to complete:

Align and shim the door: Place shims between the door jamb and studs behind each hinge to ensure the door is plumb and centered in the opening. Use a level to verify alignment both on the back side and interior face of the jamb, adjusting the shims as needed.
Secure the hinge side: Fasten the frame to the rough opening using finishing nails or screws, depending on the door type. Drive two nails or screws through the frame, shims, and studs at each shim location, ensuring they embed into the studs for security.
Shim the latch side: Align the latch side with the wall, ensuring the door hangs vertically and level within the frame. Maintain adequate spacing between the door, latch jamb, and head jamb. If the gap at the top of the door is uneven, adjust the latch jamb accordingly. Check that the gap under the door is at least 7/8 inch.
Secure the latch side: Use finishing nails or screws to fasten the latch side frame to the studs through the shims. If you see that the shims are protruding past the jamb, score them with a knife and break them along the line.

5. Install the Door Casing

The next step is to set the door casing around the door. Nail the casing into place on the door jamb and studs. Spacing the nails around 16 inches apart, drive #6 finishing nails through the casing and into the studs.

6. Attach the Hardware

You can now customize your interior door by installing the backplates, door knobs or handles, and the strike plate. Finally, caulk and paint or varnish your casing if you've chosen a blank door.

Take Extra Care with Solid-Core Doors

Solid-core doors are much heavier than hollow-core doors. If you choose a solid-core option, it's best to get help when lifting and positioning your door. This will protect you and the door.

Be aware that a heavier door may also require heavier-duty screws and more hinges to support its weight.

Self-Installation or Professional Installation Services? If you have some previous experience installing doors or undertaking other DIY projects, installing pre-hung doors shouldn't be too challenging. However, the installation process can be tough if you're new to DIY or don't have the strength or time to do it yourself.

According to the International Association of Certified Home Inspectors, more than 300,000 door-related injuries requiring emergency room treatment occur every year. 45,000 of these accidents involve children under the age of 14. Getting help from professional installation services may reduce the risk of accidents in your home, save you a considerable amount of time (and frustration!), and ensure your doors are installed to perfection.

Note: While installing a pre-hung door is within the capabilities of many homeowners, installing modern sliding doors like magic doors or pocket doors is more specialized. Your chosen sliding doors will come with manufacturer instructions detailing the installation process. If you’re familiar with similar DIY processes, you can give self-installation a go. Otherwise, opt for professional installation services.

Refresh Any Room with a New Interior Door

Successfully installing a pre-hung door can significantly enhance the appearance and functionality of your home and give it the update it needs. Remember that asking for professional help with installation is best if you're new to DIY or lack the physical strength to complete the task safely.

Always pay close attention to measurements, ensure proper alignment, and secure the door frame firmly to the wall studs. With careful planning and execution, you'll be able to enjoy your newly installed pre-hung door long into the future.