How To Create an Interior Door Opening

Adding a new interior door opening can improve how your home feels and functions. Whether you’re adding a new closet, connecting rooms, or updating your home’s layout, this guide will cover how to create a new interior doorway opening for your project. This Old House general contractor Tom Silva walks through this process in the video above.

Tools and Materials Needed To Create an Interior Door Opening

These are the tools and materials you’ll need for this project:

• 2-inch by 4-inch lumber for framing
• Circular saw
• Drill/driver
• Door frame and hinges
• Hammer and chisel
• Level
• Nails and screws
• Reciprocating saw
• Safety goggles and gloves
• Shims
• Utility knife

Planning Your New Door Opening

Before grabbing a saw, spend time planning where your new door will go with these considerations.

Choosing the Right Location

To avoid electrical wiring or plumbing, use a stud finder with electrical sensing capabilities to locate wires within the walls. Also, check your home’s blueprints or consult a professional to understand the path of any plumbing pipes behind the walls.

Keep an eye out for load-bearing walls that are crucial for the structural integrity of your home. To determine if a wall is load-bearing, check if it runs perpendicular to floor joists or consult the home’s original blueprints. If you’re unsure, consult with a contractor or structural engineer before proceeding.

Consider how close the new door will be to other doors or windows in the space. Ideally, your new door should be placed at least a few feet away from existing doors and windows to avoid crowding the space and to ensure that traffic flow within the room remains smooth and functional.

Measure and Mark the Opening

Follow these steps to measure and mark your door opening:

1. Measure the door you plan to install, including its frame.
2. Add 2 inches to the width and height for the rough opening.
3. Use a level to draw plumb lines on the wall, marking the rough opening.
4. Apply painter’s tape along the lines to outline the cut area.
5. Double-check measurements to avoid errors.

Cutting the Opening for the Door

With your planning done, it’s time to cut the new door opening. Begin by removing the wall covering. Use a reciprocating saw to carefully cut through the drywall or plaster along your marked lines. Don’t forget to cut the baseboard as well. Once the wall covering and baseboard are out of the way, watch out for any electrical wiring or plumbing inside the walls—if you come across any, you’ll need to reroute them.

Now it’s time to frame the opening. Here’s how to do so:

1. Install short 2-inch by 4-inch blocks under the subfloor for support.
2. Set a 2-inch by 4-inch sill plate on top of the vertical blocks and nail it in place.
3. Install a 2-inch by 4-inch header across the top of the doorway opening.
4. Add king studs to either side of the opening to support the header.
5. Make sure all framing members are securely nailed together to prevent shifting.

Silva demonstrates these framing techniques in the video, ensuring secure connections between the new and existing framing members.

Preparing the Door and Frame

With the opening ready, it’s time to prepare the door and frame. First, assemble the door frame. You can get a single-rabbeted door frame from a mill shop or home improvement store. Temporarily set the door into the frame to check for fit and spacing, then mark the hinge locations on the side jamb. If the door edges are uneven, give them a quick sanding so the door fits snugly within the frame.

Cut Hinge Mortises

Cutting hinge mortises gives the hinges a flush fit for smooth door operation. Follow these steps:

1. Remove the door from the frame.
2. Create a routing template for consistent mortise cuts.
3. Use a router with a templating bit to cut the hinge mortises.
4. Square up rounded corners with a hammer and chisel.
5. Test fit the hinges in the mortises before securing to ensure accuracy.

Once the mortises are cut, place the hinges in and secure them with screws. Attach the head jamb to the side jambs to complete the frame assembly, and then check that the door swings freely.

Installing the Interior Door

With the frame prepared, you’re ready to install the new door. Start by preparing the threshold. Install two 3/4-inch-thick filler strips on top of the sill plate, then nail an oak threshold on top for a finished look. Make sure the threshold is level to prevent any gaps under the door.

Set the Frame

Next, set the frame in the rough opening. Stand the assembled doorframe in place, then use a 4-foot level to check that the frame is plumb in both directions. Insert shims behind the hinge-side jamb to get it perfectly vertical, and then secure the jamb to the rough opening using a pneumatic finishing nailer. 

Hang the Door

Hang the door by attaching it to the hinges on the secured jamb. Close the door and check for an even gap between the door and the frame. Insert shims behind the latch-side jamb to keep the spacing consistent, then secure the latch-side jamb with the nailer. 

Finish the Installation

Finish the installation by scoring and snapping off any protruding shims flush with the frame. Install casing around the doorframe to cover the rough opening. If necessary, trim the baseboard using an oscillating multi-tool. Drill the lock-side jamb to receive the strike plate for the doorknob, then sand any rough edges and touch up the paint or stain to match the existing decor.

Our Conclusion

Adding a new interior door opening can enhance your home’s functionality and flow. With good planning, the right tools, and a focus on the details, you can add a door to an interior wall. Prioritize safety during this project by wearing safety glasses and gloves, and consult a professional if you’re unsure about any part of the process.