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How To Install Three-Piece Crown Molding: Plans and Instructions

Use crown molding to change the look of a living room or dining room.

About This Project

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. 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. We’ll also walk you through the tricky cuts at corners.

The built-up crown designs shown here take a bit longer to put up than single-piece crown, but the results will be better, especially if you have little trim experience. With any crown, corners are the most time consuming. If you have a simple four-corner room, you and a helper can probably install all the moldings in a day. A room with six or eight corners might take a full weekend. Painting or finishing will also add a day or two.

Our three-part pine crown cost about $3.50 per linear ft., or about $200 for a 12 x 15-ft. room. That’s slightly less than the cost of single-piece crown molding of about the same size. Hardwood molding like oak or maple will cost 30 to 100 percent more, depending on where you live. If you don’t have a vehicle that can haul long moldings home, ask about delivery charges when you compare prices.


How To Install Three-Piece Crown Molding: 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. 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.

 

 

Figure A Three-Piece Crown


Figure A Three-piece crown

The built-up crown we chose for this project combines standard crown molding with two pieces of base trim. The result is a large, dramatic crown that’s easier to install and less expensive than single-piece crown molding of similar size.

 

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. For the advantages of a brad nailer. Brand-name miter saws start at about $125. The other tools and materials you’ll need for this project are inexpensive.

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. 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.

Outside Corners and Spliced Pieces Last
Outside corners 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.

Figure B Order of Installation

Figure B Order of installation
Click image to enlarge.
At inside corners, a coped end fits over a square-cut end. In rectangular rooms, the last piece is often coped on both ends. In odd-shaped rooms like this one, you can usually avoid double-coped pieces. Outside corners are formed by two miter cuts.

Masking Tape Eliminates Fussy Touch-Ups
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’s 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. 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. Use a sharp knife blade and apply just enough pressure to slice through the tape.


How To Install Three-Piece Crown Molding: Creating a Foundation With Rail Trim

Fastening crown molding directly to walls can be a headache, but well-fastened rail trim makes nailing the crown fool-proof. 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. 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 except that you stand the trim upright against the saw’s fence when you make the 45-degree miter.

Customize Your Saw to Miter the Crown
Make square cuts with the crown lying flat on the miter saw’s bed. 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. Pencil lines on the bed or fence can help you position the crown right, but fence extensions and stop blocks make positioning fast and fool-proof. 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.

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.

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:

Shave 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:

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. 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. 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 non-square inside corners—such as 45-degree corners in a window bay—you have to miter them. Find the correct angle for each corner. Treat odd-angle outside corners just like square outside corners.


How To Install Three-Piece Crown Molding: 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:

Built-Up Crown: More Options, Fewer Frustrations
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. 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.


Copyright ©2005 Home Service Publications, Inc
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