Types of Interior Trim and Molding
Interior trim serves both functional and aesthetic purposes. Baseboards protect walls at the floor line while providing finished transitions. Crown molding adds architectural interest at ceiling-wall junctions. Casings surround doors and windows, concealing gaps between frames and finished walls. Chair rails divide walls horizontally for decorative treatments. Wainscoting and panel molding create formal traditional aesthetics.
Materials Selection
Wood remains the traditional choice for trim. Poplar is preferred for paint-grade applications due to its smooth grain. Pine offers cost-effective options for stain-grade finishes. Oak provides exceptional durability with prominent grain. MDF has become increasingly popular due to dimensional stability and cost-effectiveness, though it is susceptible to moisture damage. Polyurethane and PVC offer moisture-resistant alternatives for bathrooms.
Installation Tools and Techniques
Professional installation requires precision tools. A power miter saw with fine-tooth blade makes clean cuts. Coping saws cut molding profiles for tight inside corner joints. Inside corners should be coped rather than mitered for better results that accommodate imperfect wall angles. Outside corners are typically joined with 45-degree miter cuts. Crown molding requires holding the piece at the correct spring angle against the saw fence.
Measuring and Fitting
Measure each wall individually since rooms are rarely perfectly square. For baseboard installation, the first piece cuts square on both ends against the longest wall. Subsequent pieces are coped at inside corners. All nail holes should be filled with wood filler, sanded smooth, and gaps filled with paintable caulk.
Finishing and Painting
Priming is essential for paint-grade trim. Oil-based or shellac-based primer provides the best tannin blocking. Apply two coats of high-quality paint, sanding lightly between coats with fine-grit sandpaper. Semi-gloss and high-gloss paints highlight architectural details and are easy to clean.