How to Cut Crown Molding Inside Corners

In this video, This Old House general contractor Tom Silva shows how to cut crown molding inside corners using plastic clips and caulking to finish.

But first, here are a couple of common questions we’d like to answer about this project:

How do you handle corners on crown molding?

Use a layout square to check and see if your corners are equidistant. If they’re not at a perfect 90 degree angle, use an angle finding tool (aka bisecting adjustable square) to find the exact degrees (see next question).

Once you have the right cuts for each corner, apply caulk to join the edges together.

How do you measure and cut corners on crown molding?

If you discover that your corners aren’t exactly 90 degrees apart, then you need to use an angle finding tool to bisect the angle and get the exact measurement.

Once you have the measurement, take your angle finding tool and line it up on your miter saw with the laser light to create a center line.

How to Cut Crown Molding Inside Corners

1. Fasten the plastic installation clips to the wall using 2-inch drywall screws. Space the clips 12 inches apart.
2. Place a small piece of painter’s tape a few inches below each clip, indicating the clip’s location.
3. Use a large layout square to determine if the inside wall corners are square.
4. For out-of-square corners, use a bisecting adjustable square to set the wall-corner angles.
5. Adjust the power miter saw’s blade angle using the bisecting adjustable square.
6. Place the molding upside down against the saw fence, and make the compound-angle miter cut for the inside corner.
7. Measure the wall to determine how long to cut the crown, then cut another compound angle on the opposite end of the molding.
8. Hold crown in place against the installation clips, then use the heel of your hand to firmly tap the molding into the clips.
9. Cut a miter angle on the adjoining length of molding, then apply a bead of acrylic latex caulk to miter joints.
10. Slide the adjoining length of molding tightly against the first piece, then tap it into the clips.
11. Fill any gaps between the crown molding and ceiling with caulk.

Tools