How to Install Crown Molding

Installing Crown Molding
You will get better results by installing crown molding with a power nailer. JodiJacobson/Getty Images 
Overview
  • Working Time: 4 - 8 hrs
  • Total Time: 1 - 2 days
  • Yield: 1 medium-sized room
  • Skill Level: Advanced
  • Estimated Cost: $60 to $100

Are you looking for ways to add ambiance and value to your home for little work at moderate cost? Then consider installing crown molding. Few other remodeling projects give your home such a luxury look with so little time and investment. Crown molding is a value-added home project that takes just a weekend to makeover a medium-sized room.

You may be hesitant to take on crown molding installation, especially if you've studied videos and articles showing that cuts that are less than precise can lead to misaligned trim that can be cured only by using a new piece of trim. But a patient DIYer who works carefully can certainly get good results with this project.

The Advantages of Crown Molding

The term "crown molding" refers to accessory trim that wraps around the inside perimeter of a room at the junction of the walls and the ceiling. It is often positioned at a 45-degree angle to the wall and ceiling surfaces, but some crown is angled, or "sprung," at 52 degrees from the wall surface and 38 degrees from the ceiling surface.

Crown molding gives rooms an extra-fancy touch for little extra cost. Providing crisp, neat lines, crown molding helps to separate ceiling colors from wall colors. Crown molding can help disguise minor wall or ceiling issues at the junction. It is especially helpful when you are remodeling early 20th century and 19th-century homes, as it fits in with styles from those periods. Crown molding is sometimes installed along the tops of kitchen or bathroom wall cabinets to dress up the soffits and improve the look of the cabinetry.

Safety Considerations

Installing crown molding always involves working above the floor on ladders. Long sections of crown molding can be unwieldy, so it helps to have an assistant hold the far end of the crown molding. The assistant can either stand on a ladder at your height or can stand at ground-level and control the crown with a pole.

What You'll Need

Equipment / Tools

  • Tape measure
  • Power miter saw
  • Paint brush
  • Stud finder
  • 2 6-foot stepladder
  • Carpenter's pencil
  • Brad/finish nailer
  • Caulk gun

Materials

  • Crown molding (MDF or wood)
  • Paint primer
  • Brads or finish nails for power nailer
  • Wood filler or wood putty (if needed)
  • Paintable caulk
  • Painter's tape
  • Glossy trim paint

Instructions

  1. Measure the Room

    Measure the room for total linear wall length. For example, a 165-square-foot room with two 15-foot walls and two 11-foot walls could be completed using one 12-foot section of crown molding for each short wall and two 8-foot sections for each of the long walls.

    Make sure to buy enough crown molding to cover the walls, with some excess for waste. Buying about 25 percent more molding than you need is a good plan. If possible, it is best to cover the walls with long single pieces rather than to join pieces together, as it can be tricky to joining pieces together end to end. Most home centers will carry crown molding pieces in 8- and 12-foot lengths, but a specialty lumber yard may carry 16-foot lengths.

  2. Cut the Crown Molding

    Measure and mark the crown molding piece for cutting. While you can miter-cut crown molding with a manual miter box and saw, it's better to use a power miter saw, as cuts will be more precise.

    Unlike the technique used to cut construction lumber, where you position the workpiece flat against the miter saw table and fence, crown moldings are cut with pieces positioned at a 45-degree angle, upside-down on the miter saw table. The top edge of the crown molding that will meet the ceiling goes flat against the horizontal saw table, while the bottom edge of the crown molding rests against the vertical back fence of the saw. The piece of crown molding will be positioned at an angle as you cut it.

    This technique can be tricky, so it's a good idea to practice with some scrap pieces before you turn to cutting full pieces of molding.

    To cut pieces that will meet at inside corners: An inside corner is one with a concave, inward-facing 45-degree angle. For the left side of the corner, miter-cut with the saw blade rotated right at 45 degrees. Discard the left side of the cut and save the right side of the cut. For the right side of the corner, rotate the saw blade left at 45 degrees. Discard the right side of the cut and save the left side.

    To cut pieces that will wrap around an outside corner: Outside corners have a 45-degree convex angle that points in an outward direction. For the left side of the corner, rotate the saw blade right at 45 degrees to make the cut. Discard the left side of the cut and save the right end of the cut. For the right side of the corner, rotate the saw blade left at 45 degrees. Discard the right side of the cut and save the left side. 

    To cut straight pieces that will butt: Often, the crown molding will not reach the entire length of a wall. A nearly invisible way to stitch two straight pieces is with a scarf joint. Cut the left piece at 45 degrees, as if cutting it to fit into the left side of an inside corner. Cut the adjacent, right-hand piece as if cutting the right side of an outside corner. The two pieces will butt neatly together in the center of the wall. This is a much more professional-looking joint than simply butting the pieces together with square cuts.

  3. Prime the Wood

    MDF molding often has a paint primer already applied, but if you are using bare wood moldings, it is a good idea to prime the wood and let the primer dry for at least an hour before installing it on the wall.

    Some carpenters like to also apply the finish paint to each piece before nailing up the crown molding. You can do this if you wish, but you should expect to do some touch-up painting after the moldings are installed. In our example, we will paint as the last step, after all the moldings have been nailed in place.

  4. Find and Mark Wall Studs

    Use a stud finder and pencil to locate and mark each wall stud on the wall surface a few inches down from the wall/ceiling joint. These marks will serve as a guide when you nail up the crown molding pieces.

  5. Install the Crown Molding

    To install your crown molding on the wall, flip it over so that it is upright. Recruit a helper to help you manage the molding on a second ladder as you position it into place. Begin at the center of the wall.

    The crown should form a 45-degree angle against the wall and ceiling (or 52 and 38 degrees from the wall and ceiling, respectively, depending on the molding type). Make certain that the angle is precise. Most moldings have flat faces on the top and bottom edges that are designed to fit flush against the wall and ceiling. Problems with the angle will become apparent at the corners

    With a power nailer, drive brads or finish nails through the molding into wall studs or into the top plate of the wall. Make sure to nail the joints securely in the corners and at scarf joints where molding pieces are joined at the ends.

    If the brads have left recess holes in the moldings, you can fill these with a dab of wood filler or putty applied with your finger.

  6. Caulk Gaps

    Because walls and ceilings are rarely perfectly flat, it's normal to see some occasional gaps between the molding and the walls and ceiling. Run a bead of flexible, paintable caulk along these gaps to fill them. Caulk can also fill any remaining gaps at the mitered corners.

    Smooth the caulk with a wet finger, and let it dry according to the manufacturer's directions before you paint the moldings.

  7. Paint the Molding

    If you have not yet painted the moldings, begin by applying painter's tape along the top and bottom of the moldings where they meet the wall and ceiling. (Very skilled painters may find it possible to paint "free-hand" without the use of painter's tape.)

    Paint all the moldings and let the paint dry according to the manufacturer's directions. If necessary, apply a second coat to cover more completely.

Tips for Installing Crown Molding

  • One alternative to miter cutting crown molding is coping. Because crown molding swells and contracts with the seasons, coped joints do not open up as much as mitered joints do.
  • If you have an entire house of crown molding ahead of you, purchase a crown molding support: a brace that firmly holds the trim up against the ceiling. 
  • Purchase the longest possible crown molding, as this will help you span entire walls without patching together two pieces with scarf joints.

When to Call a Professional

Few tradespeople specialize only in crown molding installation. But large metro areas, especially those with older housing stock, may have some individuals or small firms that do only trim, molding, and millwork fabrication and installation.

Some trade carpenters specialize in cabinetry and trim work. This kind of pro is a very good option if you want a truly quality installation. You can search for suitable contractors using an online matching service such as HomeAdvisor using a search term such as "interior trim" or "molding installation."

Crown Molding Variations

In addition to the standard type of installation, there are some variations you can consider.

Installing Crown Molding on Vaulted Ceilings

With regular crown molding installation, every angle is 90 degrees, but it can get more complicated if the wall-to-ceiling angle is more than 90 degrees, such as with a vaulted or arched ceiling. Installing crown moldings in this situation is not impossible, though. Rather than trying to reconcile 90-degree angle walls with walls that are anything but 90 degrees, you can build a flying crown, much like cabinet crown installation where the top is left open. During the day, this can give the room a desirable shadow effect. Or you can install lighting behind the crown molding to create a pleasant aura at night.

Using Corner Blocks

If you anticipate having a hard time mitering crown molding corners, corner blocks are one way to avoid nearly all miter cuts.

Corner blocks are pieces of trim that are installed on inside or outside corners. They substitute for the 45-degree junction or coped joint of two crown strips. Each strip meets straight onto the block at a 90-degree angle. Not only do corner blocks make installation easier, they also add an ornate, elegant, and elaborate touch to your home.

Adding Lighting

Crown molding does not always have to be installed against both the wall and the ceiling. For a fun effect, consider installing the crown only against the wall and moving it downward about one or two inches. The gap you create at the top provides a V-shaped pocket that can disguise speaker wires or LED tape lighting.

Older-style heavy plastic tube-covered rope lights are slowly being supplanted by ultra-lightweight LED tape strip lighting. These are perfect for installing behind gapped crown molding to add cool, exciting, and lively moods to a room. Also, lighted crown molding can act as a friendlier substitute for the glaring general room lighting of ceiling fixtures.

Consider Alternative Materials

There are two alternatives to rigid wood crown molding. The first is a flexible plastic crown, such as Easy Crown Molding, that can be cut with scissors and applied with peel-and-stick adhesive. The second is a rigid, high-density polystyrene molding, such as So Simple Crown, that is is cut with a miter saw. These flexible products are easy to cut and install. Their flexibility allows them to conform to wall imperfections. However, the peel-and-stick adhesive can loosen and fail over time.

Rigid polystyrene crown is closer to real wood crown molding. Because it is light-weight, it can be applied with caulking. Unlike wood, it is not affected by changes in relative humidity. One disadvantage is that, upon removal, the molding may damage the ceiling and walls because the caulking may pull away paint, drywall paper, or plaster. Caulking residue may also be left behind.

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