How to Install Crown Molding

The first time I installed crown molding, I probably wasn’t installing it at all—I was just getting my dad’s tools off the truck. Since then, I’ve kept it in eight or 10 rooms, and about half a dozen bookcases and closets. Crown can go in any space, from the kitchen to the den, and of all the interior trim found in the home, none draws more attention. A room with a high crown at the junction of wall and ceiling is an attractive focal point that a savvy realtor will point out with granite counters and marble baths.

The 4½-inch crown on this job came from a local lumber yard — still a great place to pick a wide profile. I jumped on clear pine at $2.70 per linear foot. If I planned to paint the crown, I could get pre-finished finger-jointed pine for $1.60—and I’d be able to finish the stray gap before painting.

Installing the crown is a bit more difficult than other trim because it requires cutting compound angles. Also, out-of-square corners and raised, wavy walls can be a nightmare for the novice. But throughout a dozen jobs, I’ve taken some shortcuts–I don’t remember where I learned a lot of these tricks, I just know them.

How to Install Crown Molding

Site preparation

Crown molding is usually nailed to the wall studs along the bottom edge and into the ceiling joists above—a lot of stud finder work. I leave it all out by placing a plywood backer board on the top plate (horizontal framing member above the wall studs). This method allowed me to nail the 4½-inch crown of this project anywhere along each wall.

To determine the width of the backer board, I placed a piece of crown molding against the inside corner of a framing square and drew a line along the back of the crown (1) diagonal line, minus 1/8-inch for clearance. , is the width of the backer board. I used a table saw with the blade at a 45-degree angle to rip the backer boards from 3/4-inch plywood, then nailed each board to the top plate with 3-inch drywall screws spaced 16 to 24 inches apart. Tied up.

Saw the shortcut

The power meter saw and stand to provide a safe, quick, and accurate way to perform precise cuts. Choose a 10- or 12-inch saw with a dust collection bag or exhaust port for attaching a wet/dry vacuum. Choose a stand with an integral power strip and extendable arm to support the length of the molding. The Craftsman rig I used included a 12-inch dual bevel compound miter saw ($350) and a Pro Duty saw stand ($250).

There are two ways to cut the crown: either lay it flat under the blade or set it at an angle to the saw, the way it will be installed between the wall and the ceiling. I prefer the latter. The flat method requires adjusting the saw blade to make both bevel and miter cuts. With my method, the saw table serves as the roof, the fence is the wall, and an inverted crown piece can be cut at a compound angle with a simple 45-degree vertical cut.

To hold the crown in place, it helps to fasten the cleat to the saw table. To set it up, I first clamped a length of molding along its edges against the saw’s vertical fence and horizontal table. I pressed the 30-inch, straight-edged board firmly against the crown and clamped it to the table (2). This piece, the cleat, stayed in place between cuts, so I could easily leave each crown piece in position. I cut out the center of the cleat by making a left-hand and right-hand 45-degree miter cut, opening a channel for the blade to pass through (3).

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Straight runs

Most crown molding comes in 16-foot lengths, so unless you’re carving out a gymnasium, a single piece can usually span every wall. When this cannot be done, the two lengths are joined end to end in a scarf joint (4). It joins opposing compound angle miters in a clean, almost undetectable seam.

Molding may shrink or move slightly out of position–with a scarf joint, unlike a square-edged butt joint, there will be no visible gaps at the seam. To make the scarf joint, I made a compound angle miter cut on the end of one length of the crown. I nailed the crown to the backer board and then cut an anti-compound angle miter at the end of the mating length of the crown. After applying a little wood glue to the joint, I slid the other crown piece into position and nailed it to the backer board.

Inside the corner

A copied joint joins the two pieces of crown molding at the inside corner of the room. I prefer this type of joint to a miter joint because wall corners are rarely exactly 90 degrees. A copied joint, in which a crown piece is machined to fit the curve of the adjacent profile, create a tight fitting seam even if the inside corner is out of square–as many as there are.

I cut the first length of the crown with a square end, pushed it firmly into the corner, and nailed it in place. Next, I cut a compound angle miter at the end of the mating length of the crown (1). Next, I used a copy saw to back-cut the molding along its shaped profile (2). The idea is to sew off enough wood to allow the copied cut to fit tightly against the profile of the first crown piece.

After cutting, the copied piece needed a bit of fine-tuning before it fit well. I smoothed the joint with a rat-tail, half-round and flat files, as well as a wooden dowel coated in 80-grit sandpaper (3).

Outside corner

Outside wall corners are rarely perfectly square, so cutting both crown pieces at 45 degrees usually won’t cause them to melt easily in the corner. A technique I’ve used for years is measuring the outside pea joints perfectly, regardless of the angle of the wall. I put two overlapping 20-inch long 1 x 4s against the ceiling in the corner.

I trace both edges of the bottom board onto the top board (4), then draw a diagonal line to connect the two marks. Then I stack the 1 x 4s on the miter-saw table, adjust the angle of the saw blade to match the diagonal line, and cut the 1 x 4s (5). I do a test fit by holding the 1 x 4s by the outside corner and checking the seam.

If their edges aren’t tight, not even touching, I adjust the saw for another cut. When the 1 x 4s fit the wall, I lock the angle of the saw blade and cut one of the crown lengths. Then I adjust the saw to make the opposite miter cut – at the same angle – on the end of the crown mating piece. Keeping the first crown end piece flush with the corner of the wall, I drill a pilot hole and nail it to the backer board by hand with 1½ inch 4d finish nails (fired nails hit the face of the molding). can be broken).

I apply wood glue to the joint, slide the crown mating piece into place (6) and nail it to the backer board.


(1) Trace the back of the crown to plan the backer board – installed between the wall and ceiling, this board acts as a mount for the crown.

(2) Attach a board to the miter saw to create a simple, permanent way to hold the crown in place as each piece is cut.

(3) The cleat, with a center cut, has an inverted crown in the saw at an angle. Placing the molding in the saw like this allows simple vertical chips to form the compound angle necessary for installation.

Straight runs

Straight runs

(4) Join the straight run with scarf joints, which join the pieces together in a discreet seam. Fasten it with 2-inch finish nails or 2-inch 6D hand nails.

Inside the corner

(1) Cut a square end piece on the miter saw and slide it into the corner. Cut the other piece at a 45-degree angle.

(2) Use a coping saw to cut the back of the second piece of molding, so that it conforms to the profile of the square finished piece.

(3) Fix the cupped molding by sanding it with a dowel rod wrapped in 80-grit paper.

Outside corner

Outside Corners

(4) To make the correct cut on the out-of-square walls, start by tracing the edges of the two 1 x 4s. Connect the lines.

(5) Cut both pieces along the joining line. Once you get the boards flush against each other at the corner, the saw is set at the correct angle.

(6) Two mirrored pea-cuts will give an excellent outside corner – the pieces will fit together neatly.


Hello My self Emelia , I'm a Technology & Gaming Guides Expert. OR Also Providing Gaming Guides For Public information.

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