Mouldings are profile-cut lengths of wood, medium-density fiberboard, foam, or polyvinylchloride that are placed around openings such as windows and doors, or around ceilings and floors to give them a finished, decorative appearance. Moulding and millwork comes in a wide variety of types, including crown molding; ceiling and window trim; coves and domes; medallions and rosettes; hand, chair, and wall rails; door stops; jambs and sills; baseboards; wainscoting; and much more.
Mouldings are typically supplied as components that are pieced together on the wall, ceiling, or work surface, and are secured together as one architectural ornament using nails or glue or both. Wax is used to fill any nail holes, while color-coordinated putty is used to fill cracks or gaps between the moulding components. Caulking is used at the edge where the moulding meets the wall or ceiling surface. These steps ensure that the moulding is completely smooth and seamless before painting.
While mouldings are typically made of wood, they can also be constructed using plaster, cement, medium density fiberboard (MDF), flexible polymer resins, and polyurethane. Medium density fiberboard (MDF) is made from wood fibers that are glued together under pressure and heat. The material makes is ideal for mouldings because it is stiff and has no surface grain, making it easy to be drilled, machined, and cut without damaging the surface.
Flexible polymer resins mouldings can be curved or formed into complex shapes. Resin components can be nailed or glued together just like wood moulding and millwork. Another benefit to polymer resin mouldings is that they do not deteriorate, rot, or swell like wood does. These polymer components can be used for all kinds of moulding, like keystones, corner blocks, and rosettes.
Some mouldings companies also manufacture finished products that typically require several layers of moulding. For example, mouldings like architraves feature several layers to achieve a particular effect. Modern machining techniques allow companies to mill components with intricate and complex profiles, rather than requiring the layering of multiple strips of moulding.
Other moulding and millwork components mimic classical architectural features like dentils, which are a series of blocks set a certain distance apart. Now, with materials like polyurethane and resins, these features can come in strips of particular dimensions that can be custom cut to fit in a variety of applications.