Nice looking trim does wonders for a room. Here are some tips to a sharp looking job.
Tools. Accurate cuts mean a tight fit, so use a sharp knife or scribe to mark cuts. Cut with a backsaw and miter box, a radial arm saw, a trim saw or a circular saw on a miter jig. Use a sharp, fine-toothed saw blade. A coping saw is handy, too.
For a good fit, choose your baseboards and door casing at the same time, and make sure the baseboard won’t protrude further than the casing.
Start with the door casing. Casing looks better if it’s set back to reveal 1/8 to 1/4″ of the door jamb, so start by marking this setback line on the jamb.
Now, unless you’re using door caps or corner blocks which can be butt-jointed, you’ll need to miter your angles. If your door’s square, great. If not, simple 45-degree miters won’t fit. It’s best to check each angle first and halve this number to determine the miter.
Work clockwise on door casing, making cuts in that order, and marking miters from the intersections of setback lines.
Plan baseboards carefully, beginning with the longest walls. Use full-lengths wherever possible, but if you need to splice two pieces, don’t butt them. Cut 22 1/2 degree angles (one inside, one outside).
Many carpenters cope baseboards on inside corners for a tighter fit. To do this, butt one baseboard against the wall, then hold the next piece at 90 degrees and trace the profile on it with a compass. Cut out the profile with a coping saw.
If you’re staining your trim, do this before installing it. And don’t nail anything completely until you’re certain that everything fits. Countersink the nails and finish with putty or filler.