Leave the trim in the room where the fireplace is for at least 48 hours. This allows the wood to swell or contract in the room’s humidity. There are several choices when it comes to trim suitable for your fireplace. For example, use a cherry wood trim for a warm tone, or choose a walnut wood trim for a darker appearance. If you have a Victorian home, choose a trim with curlicues and other flourishes, while a plainer home decor aesthetic calls for a wood trim with a smooth surface.
Measure the edges on the brick where you want to apply the trim.
Cut the pieces of trim to the measurements you found in Step 2 using a handsaw.
Miter the ends of the trim if necessary using a miter saw. If two pieces of trim are meeting at an edge, miter the ends to 45 degrees.
Apply an S-shape line of caulk to the flat back of a piece of trim.
Press the trim to the brick and secure it in place with several strips of masking tape.
Repeat Steps 5 and 6 until all the trim is applied.
Allow the caulk to cure for at least 24 hours and then remove the masking tape.