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What is crown molding?

Crown molding is the uppermost molding on an interior wall, where it meets the ceiling, and the same name covers the top of a cornice or a piece of furniture. It finishes and decorates that edge and is made of wood, MDF, plaster or foam plastic.

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By InstaBids editorial team with AI research agents. Updated

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What is crown molding made of?

Crown molding is made of solid softwood or hardwood, medium-density fiberboard (MDF), run plaster, or foam plastic. The USDA Forest Products Laboratory's 2021 Wood Handbook covers wood and MDF moldings, the National Park Service describes cornice moldings run in gypsum and lime, and Seattle's building code sets a rule for foam plastic trim: “Trim items such as moulding in either softwood or hardwood are available cut to standard size and pattern.” Source: USDA Forest Service, Forest Products Laboratory, read 2026-10-29. “Medium-density fiberboard is frequently used in furniture applications.” Source: USDA Forest Service, Forest Products Laboratory, read 2026-10-29. Of MDF, the handbook adds: “It is also used for interior door skins, moldings, flooring substrate, and interior trim components (Cai and others 2006, Youngquist and others 1993).” Source: USDA Forest Service, Forest Products Laboratory, read 2026-10-29. “For example, an elaborate parlor cornice consisted of plain moldings made of gypsum and lime run atop temporary lattice strips around the room.” Source: National Park Service, U.S. Department of the Interior, read 2026-10-29. In Seattle, “Foam plastics shall not be used as interior trim except as provided in Section 806.5 or 2604.2.” Source: City of Seattle, Department of Construction and Inspections, read 2026-10-29.

How do the Getty thesaurus and the National Park Service describe crown molding?

A crown molding is the top molding on a surface: on a room's wall it sits at the ceiling line, and the same name covers the top of a cornice or of a piece of furniture. The Getty Art & Architecture Thesaurus defines it, and the National Park Service lists crown molding among the interior features found in historic buildings: The Getty thesaurus defines crown moldings as “The uppermost moldings, as on an interior wall, the top of a cornice, or a piece of furniture.” Source: Getty Research Institute, read 2026-10-29. “Marble or wood wainscoting in corridors, elevator cabs, crown molding, baseboards, mantels, ceiling medallions, window and door trim, tile and parquet floors, and staircases are among those features that can be found in historic buildings.” Source: National Park Service, U.S. Department of the Interior, read 2026-10-29.

Why is it called crown molding?

The sources captured for this page do not give a dated history of the word, but they tie it to the top of a wall: the Getty thesaurus calls crown moldings the uppermost moldings, and it describes cornices, which a crown molding tops, as features crowning a window or wall: See the Getty Research Institute passage quoted above. Of cornices, the Getty thesaurus says: “The projecting, uppermost features of classical entablatures; use also for similar features crowning a window or wall.” Source: Getty Research Institute, read 2026-10-29.

What is the purpose of crown molding?

Crown molding finishes the edge where a wall meets the ceiling and decorates it. The Getty thesaurus gives finishing and decoration as the purpose of moldings in general, and the USDA Wood Handbook's glossary counts cornice and other moldings at the ceiling as part of a building's trim: The Getty thesaurus defines moldings as “Long, regular channels or projections used for finishing and decorative purposes.” Source: Getty Research Institute, read 2026-10-29. The Wood Handbook defines trim as “The finish materials in a building, such as moldings, applied around openings (window trim, door trim) or at the floor and ceiling of rooms (baseboard, cornice, and other moldings).” Source: USDA Forest Service, Forest Products Laboratory, read 2026-10-29.

What is crown molding in a house?

In a house, crown molding is the trim that runs around a room where the walls meet the ceiling. The USDA Wood Handbook places cornice moldings at the ceiling of rooms, and in older homes the National Park Service describes plaster cornices whose profile runs from the finished ceiling to the finished wall: See the USDA Forest Service, Forest Products Laboratory passage quoted above. “To replace the missing lengths, the first step is to obtain a cross-section, or profile, through the cornice from finish ceiling to finish wall lines.” Source: National Park Service, U.S. Department of the Interior, read 2026-10-29. “Plain plaster molding without surface ornamentation was usually created directly on the wall, or run on a flat surface such as a plasterer's workbench and attached to the wall after it set.” Source: National Park Service, U.S. Department of the Interior, read 2026-10-29.

What is crown molding on cabinets?

On cabinets, crown molding is the uppermost molding along the top of a cabinet, since the Getty definition covers a piece of furniture as well as a wall. The USDA Wood Handbook lists furniture and interior molding among the uses of sweetgum and names MDF as a furniture material: See the Getty Research Institute passage quoted above. “Sweetgum is used principally for lumber, veneer, plywood, slack cooperage, railroad crossties, fuel, pulpwood, boxes and crates, furniture, interior molding, and millwork.” Source: USDA Forest Service, Forest Products Laboratory, read 2026-10-29. See the USDA Forest Service, Forest Products Laboratory passage quoted above.

What is the size of crown molding?

Crown molding has no single size; the USDA Wood Handbook says wood molding is sold cut to standard sizes and patterns. Code text captured for this page sets limits only in some cases: in Seattle homes, exposed foam plastic trim used without a thermal barrier must be no more than 0.5 inch thick and 8 inches wide and cover no more than 10 percent of a room's wall and ceiling area, and Seattle's building code caps combustible trim at 10 percent of the wall or ceiling it is attached to: See the USDA Forest Service, Forest Products Laboratory passage quoted above. In Seattle homes, for exposed foam plastic interior trim, “The thickness of the trim is not more than 0.5 inch (12.7 mm) and the width is not more than 8 inches (204 mm).” Source: City of Seattle, Department of Construction and Inspections, read 2026-10-29. In Seattle homes, “The interior trim shall not constitute more than 10 percent of the aggregate wall and ceiling area of any room or space.” Source: City of Seattle, Department of Construction and Inspections, read 2026-10-29. In Seattle buildings, “Combustible trim, excluding handrails and guardrails, shall not exceed 10 percent of the specific wall or ceiling area to which it is attached.” Source: City of Seattle, Department of Construction and Inspections, read 2026-10-29.

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