Tools and Materials

Understanding Interior Door Types

When buying a new interior door, choose one that’s the same size as the old one to avoid having to cut or trim. When you're replacing the door, you have two options: you can replace just the door itself, or, if the door frame is damaged, replace it with a prehung door.

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Slab Door

A slab door is a standalone door. It doesn’t come attached to a door frame, making it a good option when you want to replace just the door but keep the existing undamaged frame. Depending on the product, a slab door may be sold with or without predrilled holes or hinge mortises.

Prehung Door

A prehung door is one that comes already attached to a door frame with hinges. It allows you to install the door and frame together as one unit. It’s a good choice when the existing door frame is damaged or for a new doorway.

Slab and Prehung Installation

A slab door can simplify replacement when the existing frame is in good condition, while a prehung door is a good option when you need to replace both the door and frame. Whichever type of door you use, there are a variety of styles available to match your home décor.

When choosing a prehung door, make sure you select the correct door swing. Because the door comes mounted in its frame, the hinge location determines whether you need a left-hand or right-hand door. For accurate swing information, check the manufacturer’s handing guide before purchasing the door.

The steps below show you how to install a slab door as well as a prehung door.

How to Replace a Door: Slab Door Installation

For a slab door installation, remove the existing door, prep the new door for hinges and hang it in the existing door frame.

Replacing the Door

Measuring and Cutting for New Hinges

Place both doors on sawhorses with the old door on top of the new door. Use a clamp to keep the doors in place, if desired. Use the old door as a template to measure and cut for hinge placement on the new door. Then remove the existing hinges from the old door.

Tip

When you have loose screws with your hardware, take a piece of painters tape, put your screws on it and tape it to your hardware. This keeps everything together and you don't lose any parts.

Before you begin cutting the new hinges, trace the location of all the preexisting cuts from the old door to the new door. Use a speed square to ensure both doors are lined up at the top. Next, use the speed square and a pencil to make a vertical mark on the new door that lines up with each hinge. It's important that the hinge marks line up correctly to ensure an accurate fit. Trace the door knob and latch plate, too.

Using a router, cut out the recess where the hinge is going to go. If you prefer, you can chisel out the entire mortise instead of using a router. Watch our DIY Basics video: How Do I Use a Chisel?

Once the hinge recess is cut, check to see if the hinge fits. If the depth is off, adjust the router as needed.

Some routers may leave a curved cut, but your hinge may have square edges. You can use a chisel and hammer to square the corners, so the hinge fits properly.

Caution

Follow the manufacturer’s safety instructions when using a router. Wear appropriate eye and hearing protection, secure the workpiece and keep hands clear of the bit. If you’re new to using a router, practice on a piece of scrap wood first.

Measuring and Cutting for the Door Knob

Replacing Interior Doors: Installing the Slab Door

Prehung Door Installation

Prehung door installation is typically part of new home build or addition. However, you might need to install a prehung door if the doorframe is damaged.

Below are high-level installation steps, but always follow the instructions provided by your specific door manufacturer for best results.

Caution

Turn off power to any electrical switches, outlets or devices near the door. Use a non-contact voltage tester to ensure the power is off.

Prehung Door Installation: Remove the Door and Frame

Use a level and carpenter square to make sure the rough opening is square, level and plumb. If the rough opening is out of square, you can use shims to make small adjustments for the new frame . Your prehung door installation information indicates how close to square, level and plumb the opening needs to be to work with your specific door. For example, a door might work with a rough opening that’s within 1/4 of an inch of square and 1/8 of an inch of level and plumb. Make sure the rough opening matches any other requirements for installation.

Good to Know

The term square indicates your corners are at 90-degree angles.

The terms level and plumb are related to square. Watch What do Level and Plumb Mean? for an explanation of these terms and demonstrations of how to check for level and plumb.

Prehung Door Installation: Securing the Door

Position the new door and door frame centered in the rough opening. Align the frame edge flush with the wall surface. Trim the side jambs as necessary to fit the door squarely in the rough opening. Allow space for the door to clear your flooring and ensure the gap under the door allows airflow per local codes.

Good to Know

Some prehung doors include a two-piece trim or casing assembly. Remove the trim, if equipped, before placing the door.

Make sure the hinge-side jamb of the new frame is level and plumb. Insert shims between the jamb and trimmer if necessary, according to your prehung door installation instructions. Once the jamb is level and plumb, drive nails into the trimmer through the stop, jamb and each shim to temporarily secure the hinge side of the jamb. Shim and level the latch-side jamb and temporarily secure it with nails. Shim the center of the top jamb and secure with a nail. The frame should now be square. The door should operate easily and the space between the door edge and the frame should be equal around the frame. Adjust if necessary and resecure the frame.

Installation of Additional Door Types

In addition to standard interior doors, there may be other door types that you want to install in and around your home. Below are several types of doors to choose from.

Sliding doors sit on top of a track on the floor. They often function as closet doors. Some sliding doors are mounted on a track above the door (see barn doors below).
Barn doors are a type of sliding door. They add style, character and depth to your home. They’re a unique design approach that’s space saving, versatile and looks great. Get tips on installing barn doors.
Bi-fold doors are hinged doors you’ll often see on closets and laundry rooms. They work great in places where space is limited. Learn how to install bifold doors.
Patio doors are options for exterior doors. Popular types include sliding patio doors, hinged/French patio doors and bi-fold/accordion patio doors. See how to install a prehung patio door.

See our interior door guide to ensure you’re selecting the right type of door for your home. Not sure if a pre-hung or a slab is right for you? Our pre-hung versus slab door guide will help you distinguish between the two and show you the best fit for your needs.

Get Ready to Replace an Interior Door

Replacing an interior door is one way to update a room and bring a new look to your space. Whether you choose a slab or prehung door, careful measuring and proper installation can help you get the job done right. See our interior door guide to ensure you’re selecting the right type of door for your home. Not sure if a prehung or slab door is right for you? Our pre-hung versus slab door guide can help you understand the differences and decide which option works for your project. Once you’ve made your choice, you’ll be ready to give your room a fresh look with a new interior door.

How to Replace a Door: Slab and Prehung Door Installation

Key Takeaways