Base Trim and Casing

Inside corners on base trim can be mitered (both pieces cut at 45 degrees to meet at 90 degrees) or coped (one piece runs into the corner, the other is cut to the profile shape and butts against it). Mitered inside corners look perfect on installation day but often open as the house settles, humidity changes, and wood shrinks. Coped joints remain tight because the coped piece presses against the face of the other piece regardless of the corner angle. Professional finish carpenters always cope inside corners and miter outside corners. A well-coped joint takes 3-5 minutes per corner but produces results that last decades. This is where patience separates amateur from professional work.