The secret for a glove-tight fit for trim corners is a coped joint. With this technique you can even make complex crown moldings fit without leaving gaps. Because inside corners are rarely square, simply butting two mitered pieces into the corner almost always looks lousy. The only foolproof method for great-looking inside corners is cutting a coped joint.
These DIY tips will help you get tight-fitting joints on doors, windows and base moldings, even if your walls are less than perfect. We'll show you how to adjust your cuts so the trim fits together on out-of-square corners and wavy walls. Get out your miter saw and follow these steps, and you'll end up with professional looking trim every time.