Crown molding is a decorative trim installed where walls meet ceilings that creates a finished transition, hides small gaps or waviness, and adds character with shadow lines; it comes in many profiles and materials, can be painted or stained, and is usually joined with mitered or coped corners for a crisp, continuous look.
What Is Crown Molding?
Crown molding is a decorative top trim that bridges the junction of a wall and ceiling. Beyond style, it helps conceal small cracks, uneven drywall, and imperfect corners while adding depth through shadow lines. Traditionally called a cornice, crown can be simple and modern or richly detailed, and it’s made from materials ranging from solid wood to paintable polyurethane.
Where and Why It’s Used
Homeowners add crown molding for several reasons:
- Visual finish: It frames a room and makes walls and ceilings feel more intentional.
- Concealment: It masks hairline gaps, slight waves in drywall, or transitions after settling.
- Design cohesion: It ties together baseboards and casings, helping trim feel like a complete package.
- Cabinetry: Crown atop kitchen cabinets fills the space to the ceiling or creates a furniture-style look.
- Built-ins and mantels: It adds a refined edge to bookcases, entertainment centers, and fireplace surrounds.
- Lighting: Large coves can house indirect LED strips for soft, uplighting effects.
Common Materials and Profiles
Choosing the right material and profile affects cost, ease of installation, and final appearance.
Materials:
- Solid wood: Poplar is stable and paint-friendly; oak, maple, and cherry suit stain-grade projects. Wood is strong and crisp but expands and contracts with humidity.
- MDF (medium-density fiberboard): Smooth, paintable, budget-friendly, and consistent. Heavier than foam; avoid in damp areas.
- Polyurethane or polystyrene: Lightweight, pre-primed, easy to cut with simple tools, and great for DIY. Ideal for high ceilings or long runs; excellent in humid spaces.
- PVC: Moisture-proof; good for bathrooms and laundry rooms. Typically paintable.
- Plaster: Traditional and often used for historic homes or complex profiles; usually a professional installation.
Profiles:
- Cove: A simple concave curve for a clean, modern look.
- Ogee: An S-shaped profile that’s classic and widely available.
- Dentil: Repeating block pattern suited to formal or traditional styles.
- Bead-and-curve or stepped: Adds layered detail without heavy ornament.
- Craftsman/flat stock: Straight lines or simple build-ups that suit square-edged trim.
- Flexible crown: Rubber-like product for curved walls or bays.
Sizing and Proportion
Proper scale makes crown look intentional rather than oversized or skimpy.
- Ceiling height guide: For 8-foot ceilings, consider 3 to 5 inches overall size; for 9-foot, 4 to 6 inches; for 10-foot, 5 to 7 inches. Larger rooms and wider casings can handle larger crown.
- Projection and drop: Crown has two dimensions: how far it projects onto the ceiling and how far it drops down the wall. Check these numbers, not just the advertised size.
- Balance with other trim: As a rule of thumb, crown should feel proportional to baseboard and door casing. If you have tall baseboards, choose a crown with comparable visual weight.
- Build-ups: Combine multiple pieces (for example, a crown plus a small cove or a flat frieze board) to create a grand look without buying extremely large one-piece profiles.
Tools and Installation Basics
A careful installation makes all the difference. Here’s a straightforward approach:
Tools and supplies:
- Miter saw with bevel capability; fine-tooth blade
- Coping saw (for inside corners)
- Pneumatic or battery brad/finish nailer and appropriate nails
- Stud finder, level, tape measure, and pencil
- Construction adhesive (optional but helpful), wood glue for scarf joints
- Caulk, wood filler, primer, and paint or stain
- Safety gear: eye and hearing protection, dust mask
Key concepts:
- Spring angle: Most stock crown is designed for a specific wall-to-ceiling angle, commonly 38/52 or 45/45. Keep the crown oriented consistently on the saw. Many installers cut crown upside down and backwards on the miter saw fence, so the fence mimics the wall and the table mimics the ceiling.
- Coping inside corners: Instead of mitering both pieces, cut one piece square into the corner. On the mating piece, make a 45-degree miter, then cope along the profile with a coping saw. The coped edge fits tightly against the face of the first piece, forgiving out-of-square corners.
- Outside corners: Use matching miters. If the corner isn’t perfectly 90 degrees, adjust the miter angle or use test scraps to dial it in.
- Splicing long runs: Use a 30- to 45-degree scarf joint over a stud, with glue and nails, orienting the lap so the visible edge faces away from the room’s main view.
- Backing blocks: For large crowns or uneven ceilings, install triangular backing blocks or a continuous ledger to give solid nailing and consistent spring angle.
- Fastening: Nail into studs and ceiling framing where possible; add construction adhesive on the back to help hold long pieces and reduce seasonal movement.
- Filling and finishing: Set nails, fill holes, sand joints, caulk the wall and ceiling edges, and then prime and paint. For stain-grade wood, use color-matched putty and avoid caulk lines; aim for tight joints.
Finishing and Maintenance
- Paint-grade: Prime all faces, including cut edges, before installation to reduce moisture absorption. After installation, caulk gaps, fill nail holes, and apply two topcoats.
- Stain-grade: Pre-finish boards before cutting to keep stain consistent. Touch up cut edges and joints after install.
- Cleaning: Dust periodically and wipe with a damp cloth. Avoid harsh cleaners on stained wood.
- Humidity: Acclimate wood trim for 48 to 72 hours in the space. Maintain stable indoor humidity to minimize movement and hairline cracks at joints.
Common Mistakes to Avoid
- Ignoring the spring angle and cutting orientation on the miter saw.
- Mitering inside corners instead of coping, leading to visible gaps as seasons change.
- Skipping stud and ceiling joist layout; nails may miss solid backing.
- Oversized or undersized profiles that don’t match the room scale or other trim.
- Not addressing wavy ceilings and walls; use caulk, backing, or scribing techniques.
- Forgetting to prime or seal end grain; paint can flash and joints can open.
- Cutting measurements too tight; many installers measure to the long point and leave a hair extra, then fine-tune.
- Over-nailing thin edges, which can split wood or deform foam.
Cost and DIY vs. Pro
Material costs vary by profile and material:
- MDF: roughly 1 to 3 dollars per linear foot
- Polyurethane: around 1.50 to 4 dollars per linear foot
- Poplar or paint-grade wood: about 2 to 6 dollars per linear foot
- Hardwood stain-grade or large profiles: higher
Installed costs by a contractor often range from 7 to 20 dollars per linear foot depending on complexity, height, and finish. Confident DIYers can save by tackling straight runs and basic corners; tall ceilings, elaborate build-ups, and historic plaster work are better left to pros.
Related Terms
- Baseboard: Trim at the bottom of walls
- Casing: Trim around doors and windows
- Chair rail: Mid-wall horizontal trim
- Picture rail: High-wall horizontal trim for hanging art
- Cornice: Another term for crown or a built-up crown assembly
- Cove molding: Concave profile used alone or in build-ups
- Shoe molding/quarter-round: Small trim at the baseboard-floor junction
- Spring angle: The installed angle of crown relative to wall and ceiling
Practical Examples
- Living room refresh: In an 8-foot room with 3.5-inch baseboards, a 4.25-inch paint-grade MDF crown balances the trim. Cope the inside corners, use a scarf joint on long walls, then caulk and paint for a crisp perimeter.
- Kitchen upgrade: Add 3-inch crown to cabinet tops to close the gap to the ceiling. Use lightweight polyurethane for easier handling on ladders and glue-plus-brad fasteners into cabinet tops.
- Bathroom moisture: Choose PVC or polyurethane crown, prime, and paint with a high-quality enamel. Avoid MDF in high-humidity spaces.
- Uneven ceilings: Install a small backer strip first, then mount crown to the backer. This creates a consistent spring angle and simplifies caulking along a wavy ceiling.
- Curved wall: Use flexible crown matching your chosen profile to wrap a bay window. Create a template and pre-fit before final fastening.