Understanding Interior Door Trim and Moulding
Choosing the best door casing for your room comes down to the look and feel you want, along with how much creativity you want to add to your home.
Because there are different kinds of moulding and millwork for use around the house,
you’ll sometimes hear terms like casing, trim and moulding used interchangeably. It’s helpful to understand which is which.
Interior Trim Materials
Interior door trim is available in a variety of materials to suit various needs. Here are some of the most popular types.
- Wood trim is a timeless material choice that remains popular today due to its natural beauty and durability. Wood trim can be painted or stained, or even clear coated to allow the natural grain to show through.
- Polystyrene is a very economical choice for door trim. Most polystyrene comes in the pre-finished form, but some kinds can be painted. Polystyrene is also lighter and much easier to cut than wood, but it’s a softer material, which means it can dent more easily.
- MDF is another lower-cost option for trim. Like polystyrene, it isn’t as sturdy as wood, but it’s easier to cut. It’s also a bit more resistant to splitting than some polystyrene products when installing with nails.
- PVC trim has several advantages over natural wood or MDF trim. It is moisture, rot and mold resistant, making it ideal for bathrooms, kitchens and basements. It is also resistant to cracking, warping, or splitting and cuts like wood. PVC is available in differing styles and textures including woodgrain.
Casing
Casing refers to the entire frame around the door. This frame is functional, as it covers any gaps between the wall and the door. It’s also decorative, as it often complements the door’s design.
Trim
Trim refers to the individual pieces that make the casing. This includes the two long side pieces and the shorter piece, also called a head casing, which covers the top of the frame. You’ll often hear trim used to refer to the moulding around the floor or windows, and that’s because it’s usually the same product and style.
Moulding
We use the word moulding to refer to the trim that surrounds a room. You might be familiar with the phrases base moulding, case moulding or crown moulding. They all refer to trim, but base moulding refers to floor trim or baseboards, case moulding to door and window trim, and crown moulding to decorative trim between a wall and ceiling.
What Are Miter Joints and Butted Ends?
Because door casing is made of three parts — the two sides and the top — there needs to be a joint of some sort. On mitered joints, the corners are cut diagonally so they fit together. Butted ends aren’t angled, and the top piece of trim rests on top of the side pieces.
When deciding on mitered or butted ends, look at the styles in your other rooms and think about your design. Mitered ends pair well with a modern or minimalist look, while butted ends are more traditional or rustic.
Popular Modern Door Trim
Narrow down your trim options by considering your style and design preferences. If you want a clean design, a minimalist or straight-edge casing will work well. Or if you want some extra character in your design, consider the textures of European or colonial casings.
Let these styles inspire you—the guide is full of even more trim ideas to spark your creativity.
Craftsman
Interior craftsman-style door casings have a thick border. This gives them a lot of potential and makes it easy to turn them into a statement piece in the characteristic open plan of a craftsman-style home.
Rustic
Rustic style incorporates simple, no-nonsense designs. Think of plain and practical straight lines you can use to enhance any design.
Colonial
The colonial style embraces texture in its casings. With colonial-style doors, you’ll find bead and cove profiles in the trim that convey a sense of elegance and old-world style.
Arched
An arched doorway adds extra flair to any design, but pairing it with the right trim will turn it into a statement piece. Because the door’s shape is out of the ordinary, consider a plain trim so as not to overwhelm the doorway.
Square Edged
Think straight, classic lines, and you’ll think of the square-edged casing. With square corners and thin trim, it pairs well with simple or minimalist designs.
Minimalist
Minimalist door casings are thin, plain and discreet. There are none of the frills of European styles or the heft of craftsman designs — just pure functionality.
European
European designs encompass pure elegance. With their substantial design and construction, they look and feel sturdier than other options. From raised renaissance leaf patterns to textured Greek designs, these door casings become a feature piece of any room.
Adding Rosette and Plinth Block Moulding
Along with the different styles of door trim and casings, there are additional touches that can be added to your trim to enhance the look. Let’s take a look at a couple of the most common, rosette trim and plinth block moulding.
Rosette Moulding
Rosette moulding blocks, or simply rosettes, are a type of interior door trim typically used where vertical and horizontal mouldings meet, such as at the upper corners of doors and windows. These blocks are usually square in shape and feature an engraved or embossed floral or geometric design at the center. Sizes can range from as small as 2 inches to as large as 8 inches square, depending on the design and scale of the trim.
Rosettes add a classic or vintage aesthetic to a room and serve a practical purpose as well. They are commonly made from PVC, wood, or polyurethane, materials that are easy to cut, install, and paint. One of their key advantages is that they simplify installation by eliminating the need for precise 45-degree miter cuts typically required to join casing pieces. Instead, the rosette acts as a decorative joint, making the process more forgiving and visually appealing.
Plinth Block Moulding
There are many distinct types of moulding and trim, each with its own place and purpose. One of those pieces is called a plinth block, and it has a specific function. Plinth block moulding is a smaller piece of trim that is normally placed at the bottom of each side of your doorways. It is designed to be a transitional piece between the vertical door casing and baseboard. Like rosettes, they are usually constructed of MDF, wood, or urethane.
Sizing is important when thinking about using plinth blocks. When selecting plinth moulding, choose a block that is taller than your baseboards, wider than your door casing, and thicker than your baseboards. This size difference ensures a clean, level transition between the different trim elements. The main functional purpose of plinth blocks is to simplify alignment and create a visually balanced connection between the baseboard and door casing, so making them slightly larger than the surrounding trim is key.
Nontraditional Trim Ideas
If you’re looking to step away from standard white or wood trim, here are some ways to make your door stand out and enhance your overall design.
Use a Thicker Moulding
You don’t need to stick with the standard-size trim for your doors. You can use a different width to make it thinner or thicker. Thinner casings give a subtle, softer feel, whereas thicker trim makes more of a statement.
Mix and Match Colors
There are nearly endless possibilities for door and trim paint colors and finishes. You can be daring, bold, loud, soft, staid or anything in between when it comes to the colors in a room. Painting your door trim opens a wide range of possibilities for your room design.
Play With Tile and Wallpaper
Using a strip of tile as trim around doors and windows is a creative and eye-catching alternative to traditional moulding. Options like subway tile or mosaic tile can introduce color, texture, and a modern flair to your space. Similarly, wallpaper offers a vibrant and versatile way to enhance door trim, allowing you to experiment with patterns and style for a bold, contemporary look.
Go With No Trim
Doors don’t necessarily need trim. Having a well-made, trimless door helps it blend into a wall, giving it the feel of a secret door.
What Color Should Trim Be?
Traditionally, trim is either stained wood or painted white, depending on the home's style and era. However, door trim doesn’t have to follow tradition. It can complement a room’s design—or even become a focal point. Choose a trim color that best suits your space, whether it’s a classic white or a bold cherry red.
In addition to color, sheen plays a key role in achieving the right look. Doors and trim should contrast slightly with the walls to stand out. A good rule of thumb is to increase the sheen level from wall to trim:
- If the wall has a flat finish, use a satin finish on doors and trim.
- If the wall is satin, go with semi-gloss for the trim.
- If the wall is semi-gloss, opt for a high-gloss finish on doors and trim.
This subtle shift in sheen helps define architectural details and adds depth to the room.
Here are a few more ideas to consider when planning your trim colors:
Try White Walls With Colored Trim
There are several ways you can combine white walls with colored trim. For example, dark blue trim can give a dignified or elegant feel to a white room. A muted blue stands out but feels more relaxed. Gray or beige trim contrasts with white walls just enough to maximize the dimensional appeal of the trim. Depending on the shade, green trim can work with white walls to either suggest a touch of nature or create a coastal vibe.
Paint the Trim Darker Than the Walls
Painting door trim a darker color than the walls draws attention away from the walls and toward the door frames and doors. This approach works especially well if you have ornate trim or richly paneled doors that you want to highlight.
Darker trim can also be a quick and effective way to give a room a more modern, dramatic feel. For a subtle variation on this look, consider painting the trim a darker shade of your wall color to create a monochromatic effect that feels cohesive yet visually interesting.
Paint Walls and Trim the Same Color
Painting walls and trim the same color achieves different looks depending on the colors and paint sheen you choose. For example, if you paint the walls and trim a light color, you’ll give a room an open and relaxed feel and make the most of natural light from the windows. Dark walls and dark trim colors work together for a stately look. As long as the color isn’t too dramatic, painting trim the same color as walls can also be a way to let the trim and walls fade into the background, allowing your décor, furniture and accessories to make a bigger impact. If you want more impact, choose a gloss or semi-gloss finish for trim and a flat or eggshell finish for walls to create a monochromatic scheme with a subtle visual distinction.
Should Your Door Match Your Trim?
There are no hard rules in interior design—only what works best for your specific space and style. When it comes to choosing door and trim colors, you generally have three main options:
- Match the door and trim
- Use complementary colors
- Use contrasting colors
Each approach offers its own benefits:
- Matching the trim and door color is a traditional choice, but that doesn’t mean it’s dull. It can bring a sense of simplicity, cohesion, and timeless elegance to a room.
- Contrasting colors make a bold statement and can turn your doors and trim into standout design features.
- Complementary colors offer more flexibility, allowing you to play with different hues, shades, and tones to create a balanced yet dynamic look.
Choosing Your Door Trim
When choosing door trim, it’s helpful to consider the overall style of your home. Whether you live in a Colonial, Traditional, or Craftsman-style house, maintaining a consistent trim style throughout can help create a cohesive look.
However, if you're more focused on the design of a specific room, trust your instincts. Choose the style, size, and color of trim that best complements your room’s design and personality.