How to Install Crown Molding: Three-Piece Design

This three-piece crown molding technique simplifies installation and the results are spectacular.

Crown molding can be intimidating, because walls often aren't flat and nailing is difficult. Don't worry. This three-piece system solves those problems. Here we'll show you how to install trim on the walls and ceiling first, then add the crown. The three combined look elegant and go up more easily than a single large piece. We'll also walk you through the tricky cuts at corners.

By the DIY experts of The Family Handyman Magazine

TIME

Weekend

COMPLEXITY

Moderate

COST

Varies

Rail trim creates a foundation for the crown molding

Crown molding can be intimidating, because walls often aren't flat and nailing is difficult. This three-piece system solves those problems. In this article, we'll show you how to install trim on the walls and ceiling first, then add the crown. The three combined look elegant and go up more easily than a single large piece.

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What you need

Before you go shopping, make a quick sketch of the room and jot down the length of each wall. If possible, buy pieces that are long enough to completely span each wall. This will save you the trouble of “scarfing” pieces together (Photo 20). Inspect each piece before you buy. Look for splits at the ends and deep milling marks that will be hard to sand out. If you plan to use a light-colored stain (or no stain at all) select pieces of similar tone. You could install crown using a miter box, handsaw and hammer. But we strongly recommend using a miter saw and brad nailer. These tools don't just make the work faster—they provide better results. A miter saw lets you shave paper-thin slices off moldings until the length is perfect.

Built-up Crown

Although crown molding is usually installed alone, you can easily combine it with other trim for a larger, richer look. The stock trim available at any home center provides dozens of possibilities. You could combine more pieces than we show here or use contrasting woods for a two-tone effect. But don't get carried away. Select a style that's compatible with your existing trim. A crown that protrudes more than 5 in. onto the wall or ceiling might be too dominant or heavy looking in a room with an 8-ft. ceiling.

Aside from style, built-up crown has this big benefit: It eliminates nailing frustrations. With one-piece crown, you can only drive nails where there's framing behind the drywall. In other areas, you have to add nailing blocks or use glue (which often makes a mess or can't form a strong bond on the narrow edge of the crown molding). With built-up crown, you deal with these trouble spots more easily when you install the rail trim. Then, when you install the crown molding, you have solid, continuous base to nail into.

Whether you copy one of the designs shown here or create your own, put together a sample and preview it in the room (Photo 1). Traditional lumberyards often have the largest selection and usually have free samples on hand. At a home center, you may have to buy short pieces to create your sample.

Multi-piece crown molding option
Another multi-piece crown molding option
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Apply masking tape to walls

You'll need chalk lines to position the rail trim, and marks at studs and ceiling joists so you know where to drive nails. Most carpenters would put these lines and marks right on the walls and ceilings and hide them with paint later. That means a lot of fussy painting along the new trim.

Here’s an easier method: Stick bands of 2-in.-wide masking tape to the walls and ceiling. Masking tape can pull off paint, so use an easy-release tape like 3M's Scotch-Blue Painter' Tape. If you plan to paint the walls or ceiling, wait a couple of weeks before you apply the tape. (If your walls or ceiling is heavily textured, this method won't work because the tape won't stick well.) Snap chalk lines and mark framing locations on the tape (Photo 2). Install the trim over the tape and leave the tape in place to protect the walls and ceiling when you paint or finish the trim. When the finishing is done, cut and remove the exposed tape, leaving the covered tape in place permanently (Photo 21). Use a sharp knife blade and apply just enough pressure to slice through the tape.

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Start with the long wall and work in one direction

A long piece of molding is clumsy to handle and hard to measure and cut accurately. Installing it first makes it easier because the first piece has square cuts at both ends—no coping.

Work to the right
With the first piece in place, add the piece to the right next and work around the room in that direction. That way, you'll make most of your 45-degree cuts with the miter saw set to the left (Photo 9). With the saw set to the left, the motor is out of the way. That makes the molding easier to hold and the cut mark easier to see. Use construction adhesive on all rail—even where you can nail into studs and ceiling joists. That way, you can use just enough nails to hold the trim in place until the adhesive sets, and you’ll have fewer nail holes to fill. Apply the adhesive lightly so the excess doesn't squeeze out and make a mess.

Miter the ceiling rails at both inside and outside corners. The corners of a room usually aren't perfectly square, so you'll have to use test pieces to find the exact angle for each corner (Photo 3). The crown molding tips and techniques shown in the rest of this article will help you install the wall rails. The wall rails are mitered at outside corners and coped at inside corners. Coping the wall rails is just like coping the crown (Photo 11) except that you stand the trim upright against the saw’s fence when you make the 45-degree miter. Outside corners (Photo 14) are fussy no matter when you tackle them. But in most cases, installing them last lets you avoid ending up with a piece that's coped on both ends. If you have a wall that's too long for a single piece of molding, install a scarfed piece last to avoid a double cope (Photo 20).

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Make a marking gauge for the crown

Fastening crown molding directly to walls can be a headache, but well-fastened rail trim makes nailing the crown foolproof. Make a marking gauge the same size as the crown, then use it to position the crown on the rail.

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Cut the first piece square

The first piece of crown molding is cut square on both ends. Measure the length on the bottom rail. Make square cuts with the crown lying flat on the miter saw's bed.

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Customize your saw to miter the crown

To make miter cuts for copes and outside corners, you have to lean the crown molding—tilted at exactly the correct angle—against the saw's fence (Photo 11). Pencil lines on the bed or fence can help you position the crown right, but fence extensions and stop blocks make positioning fast and foolproof. If your fence doesn't already have holes that let you screw on extensions, you can drill holes. Or you can fasten the extensions with hot-melt glue and pry them off later. Besides providing a taller fence if needed, the extensions let you screw on stop blocks (Photo 10).

Why Cope?

You're probably wondering why you should go through the slow, fussy process of coping when you could just miter trim at inside corners. The answer is that wall corners are never quite square, and coped joints fit tight even when corners are badly out of square. Whether you're installing crown molding, chair rails or baseboard, coping is faster than finding the right miter angle through trial and error. If you really want to avoid coping, use corner blocks (available at most home centers and lumberyards). With these decorative blocks placed at inside and outside corners, you only need to make square cuts.

Use a rasp to perfect coped ends.
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Coping isn't as hard as it looks

Coping starts with a 45-degree cut on the miter saw, just as if you were going to make a miter joint at the inside corner. This cut leaves an edge along the face of the trim that acts as a guideline for your coping saw. Cut along that edge and the resulting shape will fit against an adjoining piece of crown. Chances are your first attempt won't turn out perfectly, but after a couple of practice runs you'll be able to make good-looking inside corners. Here are some tips for smooth, successful coping:

  • Every time you cut a miter (whether for coping or outside corners), you'll set the crown upside down against the saw's fence. It's easy to get confused and cut the angle backward. To avoid mishaps, hold the molding up to the corner and draw a slash showing the direction of the cut (Photo 11).
  • Clamp the molding to the work surface. Sawing is a lot easier with the molding locked into place.
  • If the saw blade tends to slide to one side as you start a cut, make a small starter notch with a utility knife.
  • Make sure the teeth in your coping saw point toward the handle. That way, the blade will cut smoothly on the pull stroke.
  • Don’t force the saw forward. Make even strokes, apply only light pressure and let the blade advance at its own pace.

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Shave in pieces on the miter saw for a snug fit

Making a piece of crown fit between two inside corners is a combination of careful measuring and trial and error:

  • Don't bend the tape measure into a corner and guesstimate the measurement. Instead, measure in from both corners and add the two measurements.
  • Make a square cut on the end of the molding. Don't assume the factory cut is square.
  • To prepare for coping, measure from the square end and mark the miter cut position on the bottom edge of the crown molding.
  • Don't make your miter cut exactly at the mark. Instead, cut the piece about a nickel's thickness too long.
  • “Spring&rdquo the molding into place (Photo 15). If it's too long, shave a hair off the square end and try again until it fits just right.

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Four fussy spots

Outside corners
The joint at an outside corner is formed by two simple miter cuts, but making them fit takes several steps (Photos 16 – 18). Don’t rush the process—outside corners are usually prominent and so are mistakes. If the crown will have a varnish finish, select two pieces with similar grain patterns.

Double copes
If your room doesn’t have any outside corners or require scarf joints, you’ll finish the job with a piece that’s coped on both ends. This isn’t as tough as you might think. The key is to start with a piece that’s mitered to the right length. Miter both ends and hold the piece in place to check the fit. Then cope the ends as usual.

Scarf joints
On a wall that’s too long for a single piece of molding, you’ll have to “scarf” pieces together (Photo 20). The angled cuts of a scarf joint are less visible than square cuts. If you plan on a varnish finish, select pieces that have similar color and grain patterns. Cut and install the longer piece first so the shorter piece can overlap it at the joint. Glue the joint.

Odd-angle corners
Coped joints only work in square corners. If you have nonsquare inside corners—such as 45-degree corners in a window bay—you have to miter them. Find the correct angle for each corner using the method shown in Photo 3. Treat odd angle outside corners just like square outside corners.

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Finish and remove the tape

Fill and sand all the nail holes, then prime and paint as needed. Finally, remove the tape. Don't wait too long–even painter's tape will pull flakes of paint off if left for several weeks. Also be sure to cut the tape where fresh paint from the crown dripped onto it so the new paint doesn’t pull away with the tape.

Editor's Note: Turn the Room into a Workshop

I've installed miles of crown molding, so you might think every piece I cut slips perfectly into place on the first try. Wrong. I intentionally cut each piece a smidgen too long and then shave them with my miter saw until they fit perfectly. Sometimes I make three or four trips back to the saw before I finally get it right. To keep the trips short, I set up shop in the room I’m working on. This can take an hour or more and makes a mess, but it saves time in the long run. Here’s some setup advice:

  • Get everything you can out of the room. Some pieces of trim might be longer than the room itself. You need space to maneuver.
  • Keep the miter saw mobile. You'll need to move the saw from one end of the room to the other to accommodate long pieces. Setting the saw on sawhorses or a stand is only practical if you can easily move it around. In most cases, I simply set the saw on the floor and support the trim with a small block the same height as the saw’s table (Photo 11).
  • You'l need a sturdy work surface that lets you clamp down the crown molding for coping. It doesn't have to be big, just stable. I use a Black & Decker Workmate.
  • Set up two ladders—even if you're working alone. Otherwise, you’ll spend half your time dragging a ladder from one end of the wall to the other.
  • Cover carpeted floors with dropcloths; hardwood floors with cardboard or hardboard. You can work a lot faster when you’re not worried about damaging the floor.

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Miter saw
  • Air compressor
  • Air hose
  • Brad nail gun
  • Coping saw
  • Tape measure
  • Level
  • Rasp
  • Utility knife

Carpenter pencil, chaulk

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

  • Masking tape