There are hundreds of different molding profiles available, from stock patterns to custom cuts. Aside from those manufactured for special uses-door and window parts, or handrail and closet rods, for example-most interior moldings can be divided into three basic functions:

Ceiling moldings cover the gap between the wall and the ceiling
Base moldings cover the gap between the floor and the walls
Door and window moldings trim the gaps between doors and windows and the surrounding wall.
Naturally, there are many other uses for moldings as well, but this document will focus on those three. You’ll find that if you master the techniques of installing these basic types of molding, you’ll be able to handle just about any trim job you encounter.

Molding can be made out of a number of different materials-not all wood. Spruce and pine moldings are the most common, because both are relatively inexpensive, and are also soft, fine-grained woods that can be worked easily and with a minimum of splitting and splintering.

You’ll be able to find pine and spruce moldings both in solid and fingerjointed (FJ) material. FJ moldings are made from short lengths of wood glued end to end. FJ material is not only less expensive than solid moldings, but it also tends to be more resistant to warp. If you’re planning on painting the trim rather than staining, FJ molding is a good choice.

Moldings are also cut from oak, mahogany, birch, walnut and other hardwoods. Reproductions of old profiles are often manufactured from high-density polyurethane, although these products are expensive and tricky to work with and generally should be installed only by professionals.