Measure and cut the corners of the trim at 45 degrees, with a miter box and saw. Sand the cut ends to remove any splinters.
Place one side piece of trim in position over the door frame and drywall, and push in a wooden shim between the two at the top end of the trim. Make sure that the shim is pushed in to the extent that the trim lays parallel with the surface of the drywall; the end of the shim may need to be cut, to ensure that the trim lays parallel. Use a hammer to knock a 2-inch finishing nail through the trim and shim, into the wall stud frame.
Install a second wood shim 12 inches below the first shim, ensuring that the trim is parallel with the drywall. Continue in this fashion down the length of the trim, installing the shims 12 inches apart and securing the trim with the finishing nails. Install the other side piece of trim, as well as the top piece of trim, in the same way. Knock all nails just below the surface of the trim using a hole punch, and fill the holes with wood filler.
Cut off all pieces of shim that protrude out from the edges of the trim. Use a utility knife to cut through the shims so that the cut is flush with the edge of the trim.
Apply paintable caulk to the gaps between the trim and drywall, all around the two pieces of side trim, as well as the top trim. Wait for the caulk to fully dry before applying paint.
Things You Will Need
- Tape measure
- Miter saw
- Miter box
- Wood shims
- 2-inch finishing nails
- Hole punch
- Wood filler
- If you are choosing to apply a clear stain to the wood trim, use a clear caulk instead of a paintable caulk. Also, make sure no caulk sticks to the side of the trim, but only apply it between the trim and drywall.