Installing an interior door transforms your room’s appearance and improves door function when done correctly. Whether you’re replacing an old door or fitting a new slab or prehung unit, following a structured process ensures proper alignment, smooth swing, and long‑lasting performance.
Tools and Materials You Will Need
- Door panel (slab or prehung)
- Hinges (typically 3 per door)
- Door handle and latch set
- Wood shims for leveling and adjustment
- Measuring tape and level
- Power drill and screwdriver bits
- Hammer and finishing nails or screws
- Chisel and mallet (for slab door hinge mortises)
- Utility knife and pry bar
- Optional saw (for trimming door or jamb)
Step 1: Measure the Door Opening Accurately
Measure the rough opening height, width, and depth at multiple points. The door slab or prehung unit should be about 1/2 inch smaller than the rough opening to allow room for shims and adjustments.
Step 2: Decide Between Slab and Prehung Door
A slab door is just the door panel and works well when the existing frame is intact. A prehung door includes the frame and is ideal when the old frame is damaged or for new construction.
Step 3: Remove the Existing Door and Hardware
Carefully unscrew the old door from its hinges or tap out the hinge pins. Use a pry bar to remove trim or molding if needed. Save reusable hardware if applicable.
Step 4: Inspect and Prepare the Door Frame
Check the rough opening for rot, damage, and plumb (vertical) and square (horizontal) alignment. Insert wood shims behind the jamb to correct unevenness—this ensures the door hangs and operates correctly.
Step 5: Installing a Slab Door
- Place the door in the frame and mark hinge locations precisely.
- Use a chisel and mallet to mortise recesses for hinges on the door edge.
- Attach hinges to the door first, then to the frame.
- Hang the door and check for proper swing and clearance.
- Trim or sand door edges if the door binds or rubs against the frame.
Step 6: Installing a Prehung Door
- Place the prehung door unit into the rough opening.
- Use a level to check that the frame is plumb and square.
- Insert shims behind the hinge and latch side to stabilize alignment.
- Secure the frame by driving screws through the jamb and shims into framing studs.
- Test door swing and latch operation to confirm smooth movement.
Step 7: Install Door Hardware
Install the door handle, latch, and strike plate per the hardware manufacturer’s instructions. Ensure the latch aligns with the strike plate to prevent sticking or misalignment.
Step 8: Apply Finishing Touches
- Trim excess wood shims flush with a utility knife.
- Install door trim or casing to conceal gaps between frame and wall.
- Paint or stain the door and trim as desired.
- Clean the work area for a finished look.
Conclusion
Installing an interior door involves careful measuring, choosing the right type of door, and following systematic steps whether using a slab or prehung unit. When done correctly, the door will operate smoothly and enhance your interior space’s function and appearance.
Frequently Asked Questions
How long does it take to install an interior door?
Installation time varies. A slab door generally takes about 1–2 hours for a DIYer; a prehung door may take 2–3 hours including frame adjustments.
Can I reuse my old door frame?
Yes. If the existing frame is structurally sound and square, it can be reused. Otherwise, installing a prehung unit is recommended.
What if the door rubs the floor?
If the door rubs the floor, check floor level and door clearance. You may need to plane the bottom edge or adjust the threshold to ensure smooth operation.