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How to Install Crown Molding

Pro Referral > Home Guides > Handyman > How to Install Crown Molding
How to Install Crown Molding

Crown molding is a trim detail installed at the top of walls at the point where they intersect with a ceiling. In its simplest form, crown molding is designed to cover transitions in materials and hide imperfections or gaps. In practical use, crown molding, as the name suggests, is the crowning decorative element or the finishing statement in a room.


A crown molding installation can be addressed with a single piece of stock in a variety of profiles and sizes available at your local lumberyard or home center. Crown molding can also be "built-up" from multiple pieces of material, offering a virtually limitless array of design possibilities.


Just as crown details are wide and reaching, the techniques and methods used to approach its installation can be somewhat broad--the needed skills varying by the installation approach you select. Because of that, this article won’t be completely comprehensive. Instead, this how-to will offer one technique for a simple crown molding install.

Materials Tools Skill Level Estimated Time
• Crown molding • Tape measure Beginner 2 to 3 hours a day for 2 to 3 days
• Cedar shims • Pencil
• Blocking strips (optional) • Miter box/back saw OR compound miter saw
• Fasteners: 4d and 8d finish nails OR 15ga and 18ga pneumatic trim nails • Carpenter's square
• Sandpaper (180 grit minimum) • Hammer (or pneumatic nail gun)
• Masking tape (1 1/2") • Nail set
• Painter's putty • Drill driver and 3/32" drill bit
• Drywall joint compound and related tools • Ladder(s) (6ft)
• Painter's caulk • Stud finder
• Paint (eggshell or better) • Caulk gun
• 2-3" sash brush
• Coping saw (advanced)
• Wood file (advanced)

Preparing to Install

  1. 1. Purchasing Material

    Crown molding comes in a variety of profiles, themselves represented in a variety of sizes and shapes. Crown molding stock runs the full gamut. It can be cut in "clear" solid wood (stain-grade--the most expensive) all the way to MDF (Medium Density Fiberboard--the least expensive) with many other paint-grade options in between. For the project described below, a preferred material might be primed FJ (finger jointed) pine. It is an excellent mid-priced option. Pre-primed pine will save us a step, since we plan to paint away any shortcomings in our carpentry skills.

  2. 2. You and I, We are Human

    With all the talk about varying styles and techniques above, there is really only one simple factor that makes a crown molding installation somewhat challenging. We are, well, human. Take a drywalled room for example, try as we may, there is really a rather slim likelihood that even the most advanced installer, taking exceptional care is going to create a room that is 100 percent perfectly squared, across 100 percent of all its cubic space. In other words, there is no room that is absolutely true. Because walls and ceilings are not EVER absolutely square, we must make our adjustments elsewhere--in this case, with our crown molding.

  3. 3. Preparing the Walls and the Ceiling

    When coupling crown molding with a full room remodel, ensure that your ceilings and walls are painted prior to installing your crown molding. Using a stud finder, work around the room identifying stud locations. As not to disrupt painted wall surfaces, we will employ masking tape. Place a piece on the wall at each stud location, and mark the tape with a pencil.


    Because modern framing best practice is performed in a "stacked" manner, you'll likely find the ceiling framing (or joists) on a similar plane. A good framer or drywaller would have also installed nailing blocks as walls intersect with ceilings. We will utilize these "nailers" when we fasten our crown molding.


    Note: In some cases, it may be necessary to add additional triangular nailing blocks on the surface of walls running parallel to the ceiling joists.

Preparing Your Material

  1. 4. Acclimating and Pre-Painting

    One of the easiest yet most often overlooked steps in a crown molding installation is acclimation of your material. Acclimation means placing your material in the same area in which it will be installed. All wood and wood-like materials are subject to expansion and contraction. To counteract this, we acclimate our material 24 to 48 hours prior to installing it.


    Consider applying a first coat of paint prior to installing your molding. This should be done, if at all possible, in the same location where you are acclimating your material. It is important to ensure that this environment is dust free.

Advanced Installation Guide

To Cope or Not to Cope: As mentioned earlier, there are at least a few approaches to installing crown molding. A more advanced installer might install crown molding as follows:

  • A. Cut the long run to length (the molding to be installed on the longer wall in a rectangular room) and nail it into place.
  • B. Take a profile of the molding (this can be done in several different ways).
  • C. Cut the required lengths and angles for the short run.
  • D. Use a technique called "coping" to match and fit the short run of the molding into the profile of the long run.
  • E. Nail the short run into place.
  • F. Repeat until the room is completed.
  • G. Caulk & Paint as needed.

Coping is a skill, especially when it comes to crown molding, that requires a good bit of both patience and practice. Because of that, I describe a much easier approach (though some might squawk, below you'll find a "No Cope, Cheaters Install"). Once you have mastered it, graduate (on your next crown project) to the more traditional, pro-like Coped Install.

Plan the Layout

  1. 5. Cut Your Crown Molding

    One of the key things to grasp with crown molding is that it is installed on a diagonal, with only the edges of the molding touching both the wall and the ceiling. Because of this design, it is not cut flat in a miter box like other moldings, rather it must be held at an angle.


    Important! Upside Down and Backwards: Crown molding is cut "upside down and backwards." Put simply, the base of your box (or miter saw deck) acts as the ceiling and the "fence" acts as the wall. This means that if your cut needs be on the right side of a trim run, you will be making your cut on the left side instead.

  2. 6. Cutting Inside & Outside Miters

    Inside corners require inside miters and are defined by the fact that once a cut is made, you will see the cut (this is especially easy to visualize with pre-primed materials). In our installation, all our inside corners will be cut to exactly 45-degree miters. It follows that outside corners require the absolute reverse of an inside miter. In our installation, we will start at 45 degrees but may make make minor tweaks (deeper or shallower in angle) as dictated by the angle of our outside corner(s).

  3. 7. Scarf Joints

    Because material lengths for trim typically top out at around 14', we need to be prepared to gang more than one length of molding together in a single run. When installing crown in a room that has a dimension longer than your longest piece of molding, you will be required to execute a scarf joint. This is simply a pairing of your molding--one inside miter and one outside miter made at exactly 45 degrees, mated and installed at a stud location. All scarfed joints should be glued and sanded to conceal the extra cut.


    Important! Ensure that materials being cut are: 1) perfectly flushed up in your miter box, meaning that both points of contact are absolutely flush to both the deck and the fence of your box, and 2) do not move as the cut is being made.

Fit & Fasten the Crown Molding

  1. 8. Easy Install Tools

    While using a pneumatic nail gun can make fast work of a crown molding installation, you can just as easily use 8d finish nails (2 1/2" long) to accomplish the task of fastening. Nails will be driven into both the wall studs and the ceiling joists at an angle that matches the angle on which the molding is installed.


    Important! When nailing by hand it is best practice to pre-drill the molding prior to nailing. This will help avoid any splitting of your material as you nail it.

  2. 9. Measuring, Cutting, and Hanging No-Cope Crown Molding

    While a crown molding installation can be accomplished alone, there is no question that a better installation can be achieved with the help of an assistant. In rooms with 8-, 9-, or 10-foot ceilings, you will be using two six-foot step ladders, regardless of whether you are working with an assistant or not.


    This step in our how-to will be performed as follows:

    • A. Start at the wall furthest from a room entrance.
    • B. Measure the wall length at the ceiling, i.e. where the crown molding will be installed.
    • C. Add 1/32" to your measurement.
    • D. Make required cuts, two inside miters at exactly 45 degrees, one at each end.
    • E. With the help of your assistance, start at your wall corners, and, placing each end of the crown molding into them, persuade your molding into place.
    • F. Pre-Drill and nail one nail only at two studs nearest to the center of the room (do not drive these nails home).
    • G. Move your ladders, measure the adjacent wall, and this time add 1/16" to your measurement.
    • H. Make required cuts.
    • I. Apply a thin layer of painter's caulk to the cut that will mate with the molding run installed in step F (smooth your caulk such that the entire cut is covered) and repeat for mating cut on the molding that is already hung.
    • J. With the help of your assistant, persuade this piece into place.
    • K. Ensure that the far end of your molding is sufficiently bedded in the corner furthest from you and have your assistant drive a nail into the stud that is two away from that corner (only drive this nail about 3/4rds deep).
    • L. Now working in the corner closest to the run hung in step F, twist your moldings such that they are perfectly mated and install one nail at this location for both your added piece of molding as well as your previously installed piece (If needed, it's okay to slide a cedar shim behind the molding at either the wall or ceiling. The shim may help bring and hold these miters tight. Do not set these nails).
    • M. Relocate your ladder to the center of your second run and install two nails as you did in step F above (again do not drive these nails home).
    • N. Have your assistant remove the nail installed in step K above.
    • O. Repeat these steps until you have your crown hung temporarily around the room. (Note: Outside corners if they are present in your install may be adjusted slightly from 45 degrees, will be caulked prior to mating, and may benefit by the addition of a shorter 4d finish nail.)
    • P. Inspect your installation, adding shims to it again at the wall or ceiling if a gap larger than an 1/8" appears (later we will cut them off, slide them in slightly, and build up walls with drywall compound to hide them).
    • Q. With the help of your assistant, move around the room and nail off your installation. Two nails are installed at each stud location, one holding your molding tight to the wall and one holding it tight to the ceiling.

    Tip: To tighten up any miters, we will grab our nail set and run it over the length of the connecting miters in a technique called burnishing. For inside corners use the nail set's tip, for outside corners use it on its side. Basically, this technique closes any gaps found, by folding the wood fibers on the end of your material down into the gap.

Finish the Job

  1. 10. Set Nails

    If you are comfortable with the way your installation looks at this point, use your nail set to set your nails just below the surface of your crown molding.


    Note: Be conscious that your molding does not shift in this process.

  2. 11. Fill Nail Holes

    Using a ball of painter's putty, fill your nail holes. Strike them with a quick brush of your finger or sandpaper to clean away excess material.

  3. 12. Caulk

    Given the quality of your installation, it may be necessary to caulk both at your inside and outside corners as well as along the molding as it meets the walls and ceiling.

  4. 13. Paint

    Once your caulk has cured, complete your installation by adding one additional coat of paint. Employing a sash brush with its angle bristles makes this an easier task. Depending on your skill with paint, you may choose to tape off your installation prior to painting. Touch up any spots on the walls or ceiling that may have been built up or scuffed during installation.

Level of Difficulty

As mentioned at the beginning, there are many ways in which a crown molding installation can be approached. With a compound miter saw and a pretty decent grasp of math, there are guides available that will walk you through cutting molding at more sophisticated angles. These techniques may be required with complex multi-piece build-ups, however for a simple install as the one described you will not need them. Just remember: upside down and backwards and crown molding is an art.

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