The Crown Molding Corner That Made Me Walk Away for 20 Minutes
I had measured the angle four times. I had cut two pieces of crown molding — one for each side of the inside corner — and neither of them fit. The gap at the top was about 3/8-inch. I recut both pieces. The gap moved to the bottom. I recut again. Now the gap was in the middle. I put down the miter saw, walked outside, and sat on the porch for 20 minutes contemplating whether crown molding was invented by someone who hated carpenters.
Crown molding is the least intuitive thing you’ll ever install. It sits at an angle between the wall and ceiling, so every cut is a compound miter — both the angle of the corner and the angle of the molding’s spring (the way it tilts away from the wall). Nothing about it is square. Nothing is 90 degrees in real life, even if it was 90 degrees when the house was built. Here’s what finally worked.
The Technique That Saved Me
Cut crown molding upside down and backward in the saw. This is the trick that finally clicked. Place the molding in the miter saw upside down — the bottom edge (the part that touches the wall) goes against the saw fence, and the top edge (the ceiling side) rests on the saw table. Your saw now thinks it’s cutting flat stock, but the compound angle is built into how the molding sits in the saw. This eliminates the compound miter math entirely — you just set the miter angle normally (45 degrees for a 90-degree corner) and the saw does the rest.
Never trust a corner to be 90 degrees. Houses settle. Drywall corners have mud buildup. A “90-degree” corner might be 87 degrees or 93 degrees. If you cut both pieces at 45 degrees, they won’t meet. I use an angle finder ($15, the plastic Starrett protractor) to measure the actual corner angle, then divide by two. An 88-degree corner gets 44-degree cuts on each side. The difference between 45 and 44 is about 1/8-inch at the tip of the molding — enough to create a visible gap.
Cope inside corners, don’t miter them. Mitered inside corners will open up within a year as the wood expands and contracts. Coping means cutting one piece square against the wall and cutting the profile of the molding into the other piece with a coping saw so it wraps over the first piece. It’s slower than a miter but the joint never opens. I spent an entire Saturday learning to cope and now I can do a corner in about 10 minutes. The key tool: a good coping saw with a fine blade (Olson coping saw, $12, with 15 TPI blades).
What I Actually Spent
I used MDF crown molding, not solid wood. MDF is half the price ($2.50/linear foot vs $5+ for primed pine), it’s perfectly straight (real wood is never straight), and it doesn’t expand and contract with humidity. The downside: MDF cannot get wet. Don’t use it in bathrooms or anywhere with moisture. For living rooms and bedrooms, it’s the better material.
A 12×14 room with 52 linear feet of crown molding, 4.25-inch profile: $130 in MDF molding. Construction adhesive (Loctite PowerGrab, $6/tube — this stuff grabs instantly and holds the molding while you nail): one tube. 18-gauge brad nails (2-inch): $8. Caulk (Alex Plus paintable latex, $3): two tubes. Paint to match the ceiling: had it already.
Total: about $150. A carpenter quoted me $1,200 for the same room. I saved $1,050 and learned why carpenters charge $1,200 for crown molding.
The corner that made me walk away? After my 20-minute porch break, I recut it using the angle finder (the corner was 91 degrees — of course it was), coped the inside joint, and it fit with a gap you can’t see without a flashlight. My wife doesn’t know which corner it was. That’s the definition of a successful crown molding install.
