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All About Moldings

From Arts and Crafts to Colonial to Victorian, moldings go a long way to establishing the style of a house. These trim treatments create transitions that please the eye and make a style statement.

Crown molding iStock

Moldings (sometimes spelled “mouldings”) are the decorative trim pieces that surround doors and windows, run along the bottom and tops of walls, and which generally serve as a transition between building elements. From Arts and Crafts to Colonial to Victorian, moldings go a long way to establishing the style of a house.

Molding Styles from History

Each era of architecture uses its own panoply of moldings. The very earliest American houses didn’t have much in the way of moldings as they would have been an extravagance in the hardscrabble life of early colonists. What we call colonial-style moldings aren’t so much Colonial as they are Federal or Greek Revival. The proportions and shapes used in many modern moldings are based on principles of classic Greek architecture developed thousands of years ago. By combining pleasing shapes (ogees, roundovers, fillets) with pleasing proportions, these ancient artisans gave us the design vocabulary to produce the wide variety of moldings in use today

Colonial-era craftsmen produced moldings using a variety of molding planes with cutters designed to make specific shapes. Molding production gained steam with the Industrial Age in the mid-19th century, as machines were developed to churn out miles of moldings in a great variety of shapes. Victorian architecture is in a sense a celebration of the machine age, and carpenters nailed up a wide range of moldings to create the various sub-styles of the era.

Around the turn of the 20th century, Victorian architecture fell out of style, replaced by the much simpler Arts and Crafts and Colonial Revival styles. The Arts and Crafts style used square edged stock for much of its trim, employing molded material sparingly. Colonial Revival was a somewhat fancier version of the 19th century’s Federal and Greek Revival houses.

By the middle of the 20th century, the eponymous mid-century style took over. Characterized by clean lines, flush doors, and clamshell moldings, its sleek and modern look dominated the ranch houses of post-war subdivisions.

Today, a huge variety of moldings are available and you can trim your house in any style that pleases you.

Moldings Aren’t Just Wood

In previous eras, moldings were made from one of two materials—wood or molded plaster (hence the name “molding”). Damage to old plaster moldings, by the way, can be repaired on site. The earliest wood moldings were often made from pine or chestnut, both valued because of how well they could be worked with hand planes. Paint was the common finish until the Victorian era, when various clear finishes such as shellac and varnish also came into fashion. Clear finishes highlighted the variety of wood species that could be turned into moldings with modern machinery.

Today, pine moldings are commonly available, and they’re frequently sold as primed finger-jointed, or PFJ molding or trim. Finger-jointing is a process that mills a series of interlocking fingers in the ends of joining boards, enabling the manufacturer to glue short pieces of wood together to form lengths of molding and trim that extend to 16 feet or more. PFJ molding is free of knots and other imperfections, because these defects are cut out at an early stage of production. And PFJ molding is less expensive than molding milled from lengths of clear lumber. One downside is that because the different pieces of wood may have different grain characteristics, the fingerjoint can sometimes telegraph through the paint. Another paint-grade option is MDF moldings. Made from fine wood fibers, MDF provides an extremely smooth surface for painting.

There are other alternatives, including clear (meaning knot-free) pine, as well as other wood species such as poplar and alder. These are mainly intended for painting, although they usually cost more than finger-jointed material. Hardwoods such as oak are intended to be stained and top-coated with a clear finish. Custom suppliers can make molding profiles out of any hardwood imaginable, as well, although this tends to be an expensive way to go. For outdoor use, rot-proof PVC plastic trim can be a great choice.

Moldings are Shaped with Purpose

Every house has moldings around the doors and windows called casing. Window and door casing has a functional purpose in addition to its aesthetic function as a transitional element. This casing or trim covers the narrow “shim space” between the wall framing and the jambs that make up the window or door frame. If there’s a flat, horizontal piece where you might put a flowerpot at the bottom of a window, that’s properly called a stool. The window sills are the sloped section outside. Some casings have two parts – one that spans between the door or window jamb and the wall, and a second layer called backband that wraps the outer edge of the casing.

Base (or baseboard) molding runs along the floor at the bottom of the wall. When the floor is hardwood or tile, a shoe molding is often run at the bottom of the base to cover its joint with the flooring. Base molding is sometimes installed in two pieces, the main part being a flat trim board that’s about 6 inches wide. To complete the base detail, a molded piece called base cap is installed along the top edge of the trim board.

Crown molding is sometimes used around the joint between the wall and the ceiling. This can also be made of several moldings combined. Then, it’s called a built-up crown. Crown is also used on fireplace mantles, below the shelf.

Chair rail molding is often placed horizontally at 3 feet or so above the floor in formal dining rooms. Various moldings can also be combined with chair rail to create a wainscot that covers the lower part of the walls in a room.

Installing Moldings

Moldings are cut with a mitersaw, which as the name implies, is great for cutting miters. Miters are cuts of equal angles that join trim at a corner, usually 45 degree cuts on the ends of two pieces that meet in a 90 degree corner. Mitersaws can also make square cuts, and cuts at angles anywhere between 90 degrees and 45 degrees.

In addition to miter joints, molding details (base and crown molding, for example) are installed using coped joints where molding meets at inside corners. The technique for cutting a coped joint involves first cutting a miter joint, then using the miter cut as a guide to cut out the profile of the molding your joining piece will butt against. Making coped joints is more difficult that cutting miter joints, but the technique can be mastered with some practice. Today, moldings are usually installed using a cordless or pneumatic brad nailer that drives 18-gauge nails. The brad nailer can be adjusted to drive and set the nail with the pull of a trigger, leaving a small nail hole to be filled before the final coat of finish is applied.

When working on an old house, you may want to remove and save the molding for reuse. This can be a good idea because it can be difficult to exactly match the profile of an existing molding. When removing moldings, take care to protect the wall from damage by inserting a shim or metal putty knife behind the pry bar. And always with old moldings, either test them for the presence of lead paint, or just assume their paint is lead-based and use lead-safe practices.