The primary purpose of interior wood trims is to conceal joints between different surfaces and materials to create a neat and clean aesthetically pleasant look. Molding designs or “profiles” range anywhere from simple to ornate.
Simple moldings are often stock items which means they are typically readily available. Ornate or customized molding can typically require a lead time for made to order manufacturing. Wood moldings can be standalone or combined for more complex ‘sections’ or ‘profiles’. There are several types of wood for trims and the choice for interior applications often comes down to the type of finish to be applied. Wood trims are often quite simply referred to as paint grade or stain grade. Trim to receive paint should be smooth and close grained, which is often soft woods (pine or fir). Wood to receive natural or transparent finish should have uniform color and hardness. It’s important to note that paint grade can tolerate a certain amount of installation imperfections as any joint and holes can be covered up with caulk and/or primer. Stain grade carpentry must be done with more precision with respect to joints and material choice. Trim is installed after the walls, ceiling, and flooring are complete. Below are descriptions of different types of moldings and their respective applications:
Casing – Head and jamb casings hide and finish the joint between door and window frames and the adjacent wall surface.
The windowsill is the horizontal ledge at the base of the window, can be cut to fit or to hang over the face of the wall. An Apron is the vertical piece of trim below the stool of a windowsill adding an added decorative look.
A corner block is a decorative feature used to join complex casing sections often at the top corner of a door or window.
A Plinth Block is a decorative trim piece used at the bottom of a door/opening jamb casing at the floor.
A cap molding sits at the top of a window, door, or opening.
Cornice (Crown Molding) – A molded trim that “crowns” a wall at the ceiling/wall joint. A Frieze Board is a decorative bad that sits just under a cornice at the top of a wall adding an additional finish element. A ‘coped’ or ‘scribed’ joint is used where shaped moldings meet at an interior angle. One piece is square cut against the wall and the joining piece is undercut to the profile of the adjacent molding. A Cove Molding is somewhat of an inverted ‘quarter-round’ piece used to aesthetically transition between meeting surfaces.
Chair Rail – A horizontal molding on an interior wall which provides a decorative look while also preventing the backs of chairs from rubbing against and damaging the wall surface.
Base Board – A trim that hides and finishes the joint between walls and floor. A base board shoe is typically a quarter round trim used to hide the base-board-to-floor joint. A relieved back in the baseboard is a recess cut in the back of a trim which reduces the tendency for a trim to ‘cup’ or warp over time.
Type Hardwood Softwood Closed Grain Open Grain Paint Grade Stain Grade Dimensional Stability (Flexibility) Durability (Hardness) Rot resistance
Fir (Doug) x x x x x
Pine (Northern) x x x x x
Poplar x x x x
Pine (White) x x
Pine (Yellow) x x
Basswood x x
Cedar x x x
Oak (Red) x x x x x
Walnut x x x x
Cypress x x x x
Red Wood x x x x x x
White Ash x x x x x
Beech x x x x
Birch (Yellow) x x x x x
Maple x x x x x
Cherry x x x x x