Flawless crown molding installations - Pro Construction Guide

10 Pro-tested tips for flawless crown molding installations

An installer’s job isn’t finished once the crown molding is on the wall. Here are 10 post-placement tasks that will elevate the project from finished to flawless. 

  1. Spackle, don’t caulk, nail holes. If you hide the nail holes in the molding with caulk, it most likely will leave a small dimple once it’s dry because caulk shrinks when it dries. If the trim is at the top of a vaulted ceiling, nobody will see it. But on an 8-foot ceiling, it could be visible.

Tips for flawless crown molding installationsTip:
Use spackling, which doesn’t shrink, to fill the holes. Once the spackling dries, sand it lightly and the nail hole will be invisible.

  1. Caulk, don’t spackle, gaps. For gaps in the molding—at corners and joints, for instance—caulk is better than spackling. Walls tend to shift slightly from season to season as the weather heats up and cools down.

Tip: Spackling is more rigid than caulk, and when applied to gaps, it will probably crack over time. More-flexible caulk won’t crack because of minor shifting.

  1. Consider wood fillers. Most Pros swear by caulk, but some use wood fillers instead in areas where the trim needs to be perfectly smooth, like at the joints or over nail holes.

Tip: Wood filler can be easier than caulk to sand—especially if the caulk dries before you finish applying it. Before painting over wood filler, however, apply a primer.

  1. Cover dead ends. A span of molding might end at the edge of the outside corner of a wall if the design for the other side of the wall—facing another room—does not call for trim. Or a length of molding might run into an unframed window.

In those cases, you could sand and paint the blunt edge of the trim piece. But a more polished look involves capping that dead end with another, small piece of trim.

Cut the end of the long piece of trim at a 45-degree angle instead of at a 90-degree angle. Then, make an opposite cut on a remnant that mirrors that edge. Press the two pieces together to create an outside corner. The result is a finished, designed look on the side of the molding that matches the look of the front of the piece.

Tip: Glue, don’t nail, the remnant to the other piece. Tip: Glue, don’t nail, the remnant to the other piece. This is one of the most popular tips for flawless crown molding installations. Nailing it could split the wood. Smear some wood glue on the remnant, and slip it into place; it will fit snugly, and the glue will hold it.

  1. Notice outside corners. Tiny crevices at the intersection of two strips of molding at an inside corner are easy enough to conceal with caulk and paint. Variations on outside corners, however, require more work.

Tip: For a minor gap, smooth out the rough edges with sandpaper; they’ll disappear. But for wider variations, you may have to use a utility knife to manually trim the profiles so they fit together more seamlessly.

  1. Seal the bottom edge. To close the gap between the bottom edge of the molding and the wall, run a line of caulk under the entire length of the piece.

Tips: Cut the tube of caulk at a 30-degree angle so the tip can fit under the molding’s bottom lip, and then force the caulk into the seam. Squeeze the tube with even pressure, and don’t start and stop; rather, push the caulk out in a continuous motion as you sweep the entire length of the trim. Squeeze the tube from the bottom, and fold the empty part of the tube over—like you do with your toothpaste—to help you maintain even pressure. Wipe away excess caulk along the way with a damp rag.

  1. Paint when dry. It’s tempting to get the job finished quicker by painting as soon as you finish caulking. But if the caulk isn’t good and dry when you paint it, it won’t cure.

Tip: Mask off the walls and ceiling with painter’s tapeTip: Mask off the walls and ceiling with painter’s tape before brushing the finish onto the molding.

  1. Paint before installing. To make quicker work out of a molding installation, finish the trim before nailing it down. Fixing the trim pieces on sawhorses in a garage or workshop before finishing means no paint or stain will find its way onto the walls or drip onto the floor.

Tip: It’s easier to paint or stain trim pieces when they are laid out flat at waist-height than when you have to stand on a ladder to reach them.

  1. Skip the paint brush. Paint and varnish can pull the bristles right out of a paint brush if you’re applying a thick coat.

Tip: If you’re working with polyurethane trim, consider staining it with a foam roller instead of a brush. The foam easily works the coating into the molding’s decorative crevices. Follow that up by evening out the varnish with a disposable foam brush, which will flatten out any bubbles in the finish.

  1. Buy pre-finished moldings. They’re available in a variety of designs, profiles, finishes and lengths, and save the installer time on coating the trim.

— Sharon O’Malley

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