How To Trim Molding for Inside Corners?

Molding serves as an exquisite finishing touch to any interior space, offering a blend of elegance and sophistication. However, installing molding around inside corners can be a challenging task, demanding precision and skill. Properly trimmed molding can transform a room, concealing gaps and creating a seamless finish. In this comprehensive guide, we’ll delve into the intricacies of trimming molding for inside corners, providing step-by-step instructions and tips to achieve a professional result.

Understanding Inside Corners

Before diving into the trimming process, it’s essential to comprehend the nature of inside corners. Inside corners are formed where two walls meet, creating an angle that is less than 180 degrees. These corners pose a challenge due to their acute angle, requiring precise measurements and cuts to ensure a snug fit for the molding.

Tools and Materials

To embark on this project, gather the necessary tools and materials:


  • Miter Saw: Essential for making precise angled cuts.
  • Measuring Tape: To accurately measure the length of the molding required for each side of the corner.
  • Pencil: For marking measurements on the molding.
  • Miter Box: Useful for cutting angles manually if a miter saw is unavailable.
  • Sandpaper: To smooth any rough edges on the cut molding.


  • Molding: Choose the desired type and size of molding for your project.
  • Corner Braces: Optional, but they can assist in holding the molding in place while cutting and installing.
  • Wood Glue: For securing joints if needed.
  • Finishing Nails: To secure the molding in place.
How to Cut the Outside Corners of Crown Molding: 7 Steps

Step-by-Step Guide:

1. Measure the Inside Corner:

Use the measuring tape to determine the length of molding needed for each side of the inside corner. Measure from the corner to the adjacent wall on both sides accurately.

2. Mark and Cut the Molding:

Using the miter saw or miter box, set the saw to a 45-degree angle, as inside corners typically form 90-degree angles. Place the molding in the saw and make the first cut, ensuring it’s at a 45-degree angle. Repeat the process for the molding on the opposite side, cutting it in the opposite direction to create mirrored pieces.

3. Dry Fit the Molding:

Place the cut pieces of molding into the corner without securing them. Check the fit to ensure the pieces meet seamlessly at the corner. Make any necessary adjustments using the miter saw or sandpaper for fine-tuning.

4. Secure the Molding:

Once satisfied with the fit, apply wood glue to the mitered ends and join the pieces together at the inside corner. Use corner braces or clamps to hold the molding in place while the glue sets. If using finishing nails, carefully nail through the molding into the wall, ensuring the nails are countersunk for a smooth finish.

5. Fill and Sand:

If there are any gaps or uneven edges, fill them with wood putty or filler. Once dried, sand the filled areas and any rough edges for a smooth surface.

6. Apply Finishing Touches:

Once the molding is securely in place and any imperfections are smoothed out, apply a coat of paint or stain to match the room’s decor. This step adds a polished look to the molding and blends it seamlessly with the walls.

Inside Crown Corners - Fine Homebuilding

Tips for Success:

  • Accurate Measurements: Precision is key when measuring and cutting molding for inside corners. Double-check measurements before making any cuts.
  • Practice Cutting Angles: If you’re new to using a miter saw or cutting angles, practice on scrap pieces of molding to gain confidence and accuracy.
  • Use Supportive Tools: Corner braces or clamps can be immensely helpful in holding the molding in place while cutting and joining.
  • Patience is a Virtue: Take your time during each step of the process. Rushing can lead to inaccuracies and compromises in the final result.
  • Safety First: When using power tools, ensure you follow safety guidelines and wear appropriate safety gear, such as goggles and gloves.


1. What type of molding works best for inside corners?

There isn’t a single best type, as it depends on personal preference and the room’s style. Common choices include crown molding, baseboards, chair rails, or picture rails. Choose a molding that complements the room’s decor and fits the available space.

2. How do I determine the correct angle for cutting inside corners?

Inside corners typically form 90-degree angles. To create a perfect inside corner joint, cut each piece of molding at a 45-degree angle, ensuring they mirror each other when joined.

3. What if my walls aren’t perfectly square?

Irregularities in wall angles are common. Measure each piece of molding separately and cut them to fit the specific angles of each wall. Using a coping saw to cut one piece of molding to fit the profile of the other piece can help achieve a tighter joint.

4. Can I use a miter box instead of a miter saw?

Absolutely! A miter box, though it requires more manual effort, can achieve accurate cuts for molding. Ensure the box has slots at 45-degree angles for cutting and take your time to make precise cuts.

5. How do I fill gaps in the corners after installing the molding?

Use wood putty or filler to fill any gaps at the corners. Apply the filler generously and sand it down once it’s dried. This helps create a seamless finish between the molding pieces.

6. Should I paint the molding before or after installation?

It’s generally easier to paint molding before installation. This way, you can cover any cut edges thoroughly and touch up any marks or scratches that occur during installation. However, a final coat of paint or stain may be necessary after installation to cover nail holes and touch up any imperfections.


Mastering the art of trimming molding for inside corners requires meticulous attention to detail and precision. By following these steps and tips, you can elevate the aesthetics of your space, achieving flawless inside corner molding installations. With practice and patience, you’ll confidently add a touch of sophistication to your interiors, enhancing the overall appeal of your home.

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