How to Install Interior Doors

Installing an interior door is a project that calls for patience, precision, and the right tools. Done right, it improves how your home looks, sounds, and feels. Our guide walks you through the interior door installation process, from prep to finishing touches.

Choose the Right Interior Door

Choose a door that fits the space, controls sound and light, and works with your home’s style. Common modern interior doors include:

Solid vs Hollow Core

• Solid core doors are heavy and block sound. Use them for bedrooms, offices, or bathrooms.
• Hollow core doors are light, affordable, and easy to install. Best for closets and low-traffic rooms.

Learn more about solid-core vs hollow-core doors here.

Tip: Want quiet and privacy? Go solid. Just need to close off a space? Hollow core does the job without the weight or cost.

Slab vs Pre-Hung

• Pre-hung doors come with the frame and hardware attached. They’re ideal for a new construction or when you need to replace damaged frames.
• Slab doors are just the door itself. Your existing frame must be solid and properly aligned.

Tip: Not sure which to choose? The decision between pre-hung and slab doors often comes down to skill level. Pre-hung is easier for beginners. Slab doors require precise measuring, cutting, and fitting, so they're better suited for experienced DIYers or professionals.

Match Door Type to Room Use

• Glass panel doors add light between shared spaces like kitchens or offices.
• Barn doors slide over the wall, saving space in tight or high-traffic areas.
• Pocket doors slide into the wall. They offer better sound control than barn doors.
• Panel doors are traditional with raised or recessed details.
• Flush doors are sleek, flat, and modern. They’re easy to paint and clean.

Tip: Mix door types based on function, but keep finishes and colors consistent for a cohesive look.

Still not sure where to start? Our article about How to Choose Interior Doors walks you through materials, finishes, and sizing to help you make the right call for your space.

Gather Tools and Materials First

Before starting, gather everything to save time.

Tools:

• Tape measure
• Pencil
• Screwdrivers (flathead and Phillips)
• Hammer
• Wood chisel
• Long level
• Sharp utility knife

Additional Tools to Install a Slab Door:

• Sawhorses
• Carpenter's square
• Straight edge
• Blue painter’s tape
• Circular saw with a new blade
• Hand planer
• Drill with bits
• Flat spade drill bit
• Hole saw

Tip: A hinge mortising jig isn’t essential, but it helps create cleaner, more precise hinge pockets when installing a slab door.

Materials:

• Spackle or wood filler
• Sandpaper
• Shims (wood or cardboard)
• Screws
• Hinges, handles, and latch (if not pre-installed)
• Caulk

Finishing Supplies:

• Lacquer
• Paint or stain
• Small paintbrush or roller

Step-by-Step Interior Door Installation

Installing an interior door requires careful attention to detail, but it’s achievable with the right prep. Still, according to the BHG 2024 DIY Trend Report, 89% of people experience mid-project regret syndrome. That is the frustrating moment when a project starts to feel overwhelming or mistakes appear.

Taking your time with each of the following steps helps avoid this. If you feel unsure, a professional installation service will make the process smoother. We also offer guides for interior barn door installation.

1. Measure the Door Opening

Precise measurements are key for a good fit. A door that’s too large will stick or not close completely. One that’s too small will have gaps, drafts, and reduced privacy.

• Measure the height on the left, center, and right.
• Measure the width at the top, middle, and bottom.
• Use the smallest height and width and subtract 1/2 inch from each to allow for hardware and adjustments. Check out our guide for properly measuring door rough opening.

2. Remove The Old Door (if Needed)

If you need to remove an old door:

• Tap out the hinge pins from the bottom up. Have someone support the door as you remove the last pin.
• Carefully lift the door off and set it aside.
• Unscrew the hinges, handles, and latch.
• If you are reusing the handles and latch, pay close attention to how they come apart so you can reinstall them correctly later.
• If the door is stuck, gently pry it loose with a hammer and chisel, taking care not to damage the door frame or floor.

3. Prep the Frame and Floor

For pre-hung doors, the old frame can be removed entirely. Then proceed to Step 4.

If you are reusing the frame for a slab door:

• Check the frame for damage and repair it.
• Remove any screws, nails, paint, or caulk left behind.
• Fill any holes with spackle and sand smooth.
• Clean and level the floor to prevent scraping.

Check That It's Level and Square

• Use a long level to confirm that the top of the opening is flat. A sloped header will throw off the door's alignment.
• Measure diagonally, corner to corner, both ways. If the numbers match, it's square.
• Fix minor unevenness with shims behind the frame. For major damage or misalignment, consider installing a pre-hung door with a new frame.

Now go straight to Step 5.

4. Pre-Hung Interior Door Installation

Installing a pre-hung door means positioning and stabilizing the entire frame and door unit at once. It's heavy and awkward, so get help for this step.

Step One: Set the Door and Frame

• Lift the entire pre-hung door and frame into the rough opening with help.
• Center the frame and check for an even gap around all sides.

Tip: Place a spacer or shims under the door to maintain bottom clearance while you work.

Step Two: Shim to Level and Plumb

• Place shims between the wall framing and door frame at each hinge location.
• Add shims on the latch side to keep the frame square.
• Use a level to check both sides and the top.

Step Three: Secure the Frame

• Screw the frame to the studs at the hinge and latch areas.
• Don't overtighten. First, check the door's swing and alignment.
• Adjust as needed, then tighten the screws to secure the frame. But do not overtighten the screws or you’ll risk warping the frame.

Now, continue to Final Touches to complete the installation.

5. Trim And Prep the New Door (Slab Only)

If you're installing a slab door, you’ll likely need to trim it to fit your existing frame. Precision here pays off later.

Safety Tip: Always wear safety glasses when using power tools.

Step One: Mark for Trimming

• Lay the new slab on sawhorses.
• Place the old door on top, aligning the top and latch edges.
• Trace the outline with a pencil.
• Double-check measurements against the actual frame. Even slightly warped doors can throw things off.

Step Two: Prep and Cut the Edge

• Use a straight edge and score just above the pencil line on the door side with a utility knife to prevent splintering.
• Apply painter’s tape along the door side, just above the scored line, to prevent scratches.
• Cut along the pencil line with a circular saw.
• Smooth the edge with a sanding block.
• Seal any exposed wood with clear lacquer or varnish to prevent moisture absorption.

Tip: If trimming more than 1 inch from the height, split the cut between the top and bottom to keep the door balanced.

Step Three: Mark Hinge and Latch Locations

• Hinges: Measure from the top of the frame to the center of each hinge mortise. Transfer these to the slab edge using a square.
• Latch: Measure from the top of the frame to the latch hole’s center and mark it, centered from front to back.
• Score hinge and latch outlines with your knife for clean edges, but don't chisel yet.

Step Four: Dry-Fit the Slab

• Stand the slab vertically inside the frame as if it were closed.
• Shim to hold it in place.
• Make sure your hinge and latch marks align perfectly with the frame.
• Check clearances: 1/8 inch at the top and both sides; 5/8 inch at the bottom.
• Identify tight spots, mark them, and shave small amounts with a hand planer.
• Seal any exposed areas you've planed.

6. Attach Hardware (Slab Door)

Take this step slowly because misaligned hinges or latches will cause problems.

Step One: Install the Hinges

• Chisel out the hinge mortises you marked earlier. Use a sharp chisel and work slowly to avoid cutting too deep.
• Place a hinge in each mortise, mark the screw holes, and pre-drill pilot holes to prevent splitting.
• Attach the hinges securely with the screws to the door.

Tip: Want a sleeker look? Consider concealed hinges that stay hidden, swing smoothly, and have a longer lifespan than traditional hinges.

Step Two: Mount the Door

• With help, hold the slab in place and align the hinges to the mortices on the door frame.
• Screw in the top hinge first to support the weight.
• Then secure the lower hinge and the middle hinge, if present.
• Open and close the door slowly to check for rubbing or sagging.
• Adjust screws or shim hinge plates as needed.

Step Three: Install The Latch and Handles

• Drill the latch hole and knob bore using the correct size bits or hole saw.
• Insert the latch, attach the handles, and screw on the faceplate.
• Make sure the latch lines up with the strike plate. You may need to adjust the plate's position or its mortise depth for a snug, secure fit.

7. Final Touches

Once the door is installed and working properly:

• Caulk any gaps between the frame and drywall.
• Fill nail and screw holes with spackle or wood filler and sand smooth.
• If you're reusing trim, check for damage and touch it up as needed.
• Installing new trim? Measure carefully and make clean miter cuts at the corners. Nail it in place and fill any gaps or holes.
• Paint or stain the door and trim as needed. See our tips for painting pre-primed doors to get a smooth, lasting finish.
• Let the paint, stain, or caulk dry fully before closing the door.

Your Door, Done Right

Installing an interior door takes time, patience, and close attention to detail. From choosing the right door type to measuring, trimming, fitting, and finishing, each step affects how the door looks and operates.

While it's a manageable DIY project for many homeowners, errors in measurements, leveling, or hardware placement could lead to drafts, uneven swings, or long-term damage. If you're unsure, hiring a professional installer ensures precise fitting, smoother operation, and long-lasting results.