How to Install Door Frame Moulding

Door frame molding is installed to seal the area around the door frame and give a finished appearance to the door. There are different methods of installing door frame molding. The main installation difference involves the type of corner used where the pieces of molding meet. Butt joints and 45-degree corners are both popular corner finishes. Learning to perform and install a 45-degree mitered door molding corner will allow you to easily conquer other types of molding corners.

Things You'll Need

• Step ladder
• Combination square
• Pencil
• Tape measure
• Door frame molding
• Power miter box
• Quick clamps
• Hammer
• 2-inch finishing nails
• Nail set

Instructions

1. Layout the reveal of the molding by setting the combination square at 1/8th of an inch. Set the combination square against the inside of the door frame, with the blade of the square on the side of the door frame even with the wall. Place the edge of the pencil on the leading edge of the combination square's blade. Drag the square and the pencil along the door frame. Perform this step on both vertical sides of the door frame. Place two marks, one on either corner of the top rail of the door frame. Use the ladder to reach the top rail if it is beyond your reach.

2. Set the power miter box on a 45-degree angle.

3. Cut a 45-degree angle on one end of a length of door molding. Hold the molding on the top rail of the door frame, with the lower end of the miter aligned with the relative vertical 1/8th inch reveal mark. Hold the molding in place with two quick clamps. Place a mark on the door molding, where the molding crosses the other vertical reveal mark. Remove the quick clamps and cut the other 45-degree miter on the door molding. The mark that you placed on the molding will be the short side of the miter.

4. Align the corners of the top piece of door molding with the two vertical reveal lines and the reveal marks located on the top rail of the door frame. Secure the molding with two quick clamps. Use a hammer to gently tap the molding to make fine adjustments to the moldings location.

5. Place a 45-degree miter on two pieces of trim that are longer than the dimension from the floor to the top of the door frame molding placed on the top rail of the door frame. Cut one 45-degree miter and then reset the power miter box to cut a 45-degree angle in the other direction to make left and a right side. Place the trim against the wall, with the miter resting on the ground. With the pencil place a mark 1/8th of a inch above the top of the door molding that is clamped to the top rail of the door frame. Perform the same operation on the door frame molding to be located on the other side of the door.

6. Set the power miter box to perform a square cut. Cut both vertical sides of the door frame molding on the pencil mark that you created in step 5. Hold each leg into position to check the fit. If they are long, cut 1/16th of an inch off of the length and re-fit the piece of trim. When the two sides fit square and tight against the top piece of trim, nail the top trim in place with the finishing nails. Do not run the nails tight to the trim. Remove the quick clamps from the top trim.

7. Align and nail the two vertical pieces of door frame molding into place with the finishing nails. Remember to leave the nails away from the edge of the trim. Set all the finishing nails, by placing the nail set on the indentation of the nail head, and hitting the nail set with the hammer. Set the nails 1/16th of an inch below the surface of the trim.

8. Fill the nail holes with wood putty to complete the installation.

References

• Kelleher Corporation-Trim Installtion Guide
• Home Improvement 1-2-3, 2003 edition, Doors, page 345 and 346