How To Install Wood Crown Molding

You can add a hint of elegance to any room by installing wood crown molding. This decorative trim creates a beautiful transition between walls and ceilings, and elevates the overall look of your space. Learn how to complete this project in our step-by-step guide below, and watch the video above for tips from This Old House general contractor Tom Silva. 

Types of Wood Crown Molding

Wood crown molding comes in several varieties, including the following:

• Maple: Hard, dense, and excellent for intricate designs and staining
• Oak: Durable, features a prominent grain pattern, and is great for staining
• Pine: Affordable, easy to work with, and ideal for painting
• Poplar: Smooth texture, perfect for painting, and resistant to warping

Preparation and Planning for Crown Molding Installation

Measure your room carefully to determine the amount of molding you need. Choose a style that complements your room’s decor. Acclimate the wood to your home’s environment for at least 24 hours before you begin your installation project.

Planning Ahead: According to This Old House Magazine, you should store wood inside for about a week — not just 24 hours — so it can fully acclimate to the room’s humidity. Before installation, coat boards on all sides with your preferred finish. This reduces the effects of humidity and disguises any gaps that appear when the wood shrinks.

Tools and Materials

Gather the tools and materials you need before you start the installation for a smoother and more efficient building process. 

Essential Tools

Certain tools are necessary for a seamless installation. A compound miter saw will help you to achieve accurate angle cuts, while a coping saw refines those cuts for perfect corner fits. A pneumatic finish nailer speeds up the nailing process and keeps molding secure, and a chalk line makes straight guidelines on the wall. Finally, a stud finder locates studs so that you can nail elements securely, a caulk gun and a putty knife can help you to make the finishing touches, and a 2 1/2-inch sash paintbrush is perfect for painting the molding.

Required Materials

Selecting the right materials helps you to form the foundation of any successful molding project. Start with wood crown molding. Secure the molding with 2-inch finish nails and wood glue for joints. Use caulk to fill gaps along the edges for a pristine finish, and use wood putty to cover nail holes. Finish with high-gloss latex paint for a polished look. If you’re affixing molding to brick or concrete, you’ll also need construction adhesive.

Material Options: Crown molding is available in a variety of wood species, from affordable, easy-to-cut softwoods like pine, poplar, and spruce to expensive, less manageable hardwoods like oak. Stock made from paintable nonwood materials like medium-density fiberboard (MDF) and high-density polyurethane foam are also on the market. MDF is less expensive than pine but is hard and heavy, and requires an extra set of hands and a nail gun to install. Foam, on the other hand, is lightweight and is attached with adhesives rather than nails, and it doesn’t shrink or swell like wood.

Crown Molding Installation Process

Installing wood crown molding requires attention to detail and precision.

Marking and Preparation

Mark and prepare your walls accurately to lay the groundwork for a successful installation. Follow the steps below.

1. Use a scrap piece of crown molding to mark the bottom edge on the walls at each corner of the room. This establishes the path along which you’ll install the molding.
2. Connect these marks with a white chalk line around the room. Use this as a guide.
3. Locate and mark the wall studs so that you can securely attach your elements.

Make a Marking Block: According to This Old House Magazine, Norm Abram’s trick for keeping crown molding aligned is to cut a simple block of wood to match the dimensions of the crown. Position the edges of the molding on the marks, and you’ll have no problem lining up your joints. As Norm advises: “Don’t worry if the molding doesn’t land on each mark exactly because of a bulge or dip in the wall; the crown should still come out fine overall.”

Cutting and Fitting

You must make precise cuts to achieve professional-looking molding. Here’s how to cut and fit your joints:

1. Set up your compound miter saw for crown molding cuts. This allows you to make precise, angled cuts.
2. Cut a 45-degree scarf joint on the first piece of molding. Scarf joints create a smooth transition between two pieces of molding that meet along a long wall.
3. Hold the molding in place, and make sure the bottom edge aligns with the chalk line.
4. Nail the molding to the wall studs and ceiling using the pneumatic finish nailer. This secures the molding in place, and prevents any future movement or gaps.

Pro Tip: This Old House general contractor Tom Silva recommends applying caulk behind inside corners before fastening: “It’s gonna fill any imperfections in that cut. So we’ll have a nice tight corner.” After caulking, tack the molding in place with your finish nailer for a seamless fit.

Creating Joints

You need to create proper joints for a seamless look. Mastering the three types of joints is key to making the molding appear continuous and smooth. Read more about the three types of joints below.

• Coped joints: These are best for inside corners and accommodate slight wall irregularities for a snug fit.
• Mitered joints: These are best for outside corners, and require precise 45-degree cuts to form clean angles.
• Scarf joints: Use these along long walls to join two pieces of molding without noticeable gaps.

Key Technique: When cutting crown molding on a miter saw, you must tip the molding upside down and treat the fence of the saw as the wall and the bed of the saw as the ceiling. As This Old House carpenter Tommy Silva explains, “The most important thing that you have to know is holding the molding in the right orientation with the wall and the ceiling, and you have to hold it in that same orientation in all three cuts.”

Dealing with Corners

If you’re dealing with inside corners, create a coped joint by cutting a 45-degree miter and then using a coping saw to remove the back material. This allows one piece to nestle seamlessly into the contour of the adjacent piece.

If you’re dealing with outside corners, cut 45-degree miters on both pieces and join them with glue and nails. Correctly fitting outside corners leads to a crisp, clean look that wraps around corners seamlessly.

Special Considerations: Brick and Concrete

If you’re installing crown molding on brick or concrete walls, apply construction adhesive along the back edge of the molding. This will create a firm bond. Nail the top edge to the ceiling for additional support. Additional nailing secures the molding, and prevents movement or sagging over time.

Finishing Touches To Your Crown Molding

Complete your installation with the finishing touches below.  

• Caulk along the top and bottom edges of the crown molding to fill any gaps. Caulking smooths transitions and hides discrepancies between the molding and ceiling or walls.
• Fill nail holes with wood putty and sand them smooth once they’re dry. Concealing and smoothing nails create an even surface that blends seamlessly into the molding.
• Paint the crown molding with high-gloss latex paint for a beautiful finish. Painting seals the wood and provides a refined, cohesive look.