The door casing trim, or door casing molding, is the trim work that is on the doorjamb. The door casing trim allows a finished frame to be formed. The casing will conceal the inside of the door and will secure the doorjamb. This type of casing is available in various widths and designs; options are available to work with any interior decorations. However, regardless of the style, the installation remains the same.
Make all of the measurements for the door casing. Use a pencil mark to make the measurements noticeable throughout the project. Once you have made all of the appropriate measurements, use the miter saw to cut the casing. The miter saw should be set at a 45-degree angle and cut according to the beginning measurements that were made.
Once you have the initial measurements and cuts completed, open the door. You then need to make a measurement of the horizontal dimensions. Again, use a pencil to mark your measurements and cut the wood with the miter saw at the desired location. Once you have gotten all of the wood pieces cut for the door casing trim, use nails to attach the trim to the door casing. Once you have done this you have successfully attached your door casing trim!