The frame or moulding around a window is called the casing or trim. Both interior and exterior window moulding are available in a number of materials, colours and styles. Choosing a window moulding that complements the overall design aesthetic of the building creates a cohesive and balanced look, which can increase the value of the home. Accept windows with treatments like curtains, shades or blinds.
The most common window moulding style in today's homes is traditional-style moulding. With traditional-style moulding, the wood is cut to a profile that is similar to the cuts offered in crown or even baseboard moulding. The visible lines of the wood or polyurethane create small arches, ridges or curves that add subtle decorative details to the window trim. Typically, traditional-style moulding for windows is selected to match the same profile as the crown or decorative base moulding. For a cohesive look, choose a matching finish or stain. A matching profile in a different finish can add visual interest without appearing mismatched so long as the window trim matches other elements of the room, such as door trim or moulding.
The arts and crafts movement that gained momentum and popularity throughout the 1920s introduced a new craftsman style of homes that valued natural elements, minimal ornamentation and incorporation of building materials into home design. Window moulding in the craftsman or colonial style typically includes wider frames with minimal curvature; any curvature is typically limited to symmetrical vertical fluting. Craftsman window moulding often includes a large, sometimes bulky, window sill. Simple rosettes or plinth blocks are used to mark the corners of the window. Some craftsman-style window moulding includes a keystone that sits in the middle of the top piece of moulding to create visual interest without disrupting the simplicity of the trim. Most craftsman trim preserves the natural wood by avoiding paint and opting for a light stain instead.
There are several types of more decorative window moulding. Though craftsman-style window moulding makes use of simple rosette corner pieces, more elaborately decorated rosettes are also available. Corner pieces decorated with hand-carved appliques or onlays are more reminiscent of Victorian style decorating, which valued highly ornate designs over simplicity or function. Window moulding can also be milled to include a rope design that pairs well with heavy or velvet curtains. Large floor-to-ceiling windows can be framed with pilasters, which are large wood blocks milled to resemble support pillars even though they do not serve a structural purpose. If your window is wide and has a large space above the top pane, consider incorporating a pediment onto the top edge. A pediment resembles a gable or triangular piece of wood, plaster or polyurethane plastic that can include a decorative applique, onlay or scalloped detail.