How to Install Door Casing Molding

Door casing molding, typically referred to simply as casing, is the wood trim applied to a doorjamb. It creates a finished frame for the doorjamb and conceals the perimeter shim space used to secure the doorjamb to the adjacent wall framing. Door casing is available in a variety of widths and contours to complement any home design. The method of installation is the same, regardless of the style of casing.

Things You'll Need

• Tape measure<br />Finish hammer<br />Miter saw<br />Wood glue<br />6d finish nails<br />8d finish nails<br />Nail set

Instructions

1. Use a tape measure and pencil to mark the edge of the doorjamb, ¼ inch from the door opening. Make the first mark at the bottom of the jamb on the strike side, opposite the hinge side, and repeat at approximately 12-inch increments around the perimeter of the jamb. These marks will define the casing setback, called the reveal, and guide the attachment of each casing piece.

2. Measure the distance from the bottom of the jamb on the strike side to the bottom of the horizontal headpiece at the top of the jamb. Mark this measurement plus ¼ inch on a length of door casing, ensuring the end from which you measure is cut square and you mark what will be the inside edge of the casing piece.

3. Set your miter saw to a 45-degree angle and cut the casing piece marked in Step 2, so that the measured mark is the short point of the miter cut.

4. Position the piece of casing cut in Step 3 against the edge of the doorjamb and align it with the ¼-inch reveal marked in Step 1. Be sure the short point of the miter cut at the top extends ¼ inch beyond the bottom edge of the top jamb. Attach the casing at each mark with a 6d finish nail.

5. Open the door and measure the horizontal dimension between the inside faces of the doorjamb at the top.

6. Mark a piece of casing molding with the measurement determined in Step 5 plus ½ inch. Position the marks on the casing piece to allow them to be the short points of opposing 45-degree angles at each end of the piece. Cut both angles with the miter saw.

7. Position the casing piece cut in Step 6 at the edge of the head jamb and align it with the ¼-inch reveal marked in Step 1. Use wood glue to secure the joint between the head casing piece and the side casing piece installed in Step 4. Attach the head piece at each reveal mark with a 6d finish nail.

8. Repeat Steps 2, 3 and 4 for the remaining jamb piece on the hinge side of the doorjamb.

9. Nail the outer edge of the casing pieces into the adjacent wall with 8d finish nails spaced 12 to 16 inches apart around the perimeter to hold the casing edge tight against the wall surface.

10. Repeat Steps 1 through 9 for the casing molding on the opposite side of the doorjamb. Use a nail set to set all of the nail heads ? inch below the casing surface.

References

• YouTube: Video Demonstration Of Door Casing Installation