Introduction

Before You Get Started

Design Options
Casing is available in a variety of design styles and profile options, from square-edged designs to colonial-style molding. Rosette blocks, decorative squares that butt the casing pieces at the top corners of the door area a great Victorian-style option that eliminates the need to miter the ends of the trim.

Painting Before Installation
If you are using paint-grade door casing, you may want to paint the pieces before you cut to length and install. Use semi-gloss paint for door casing. Flat paint is harder to clean, and flat-painted casing will show any dirty fingerprints.

Step 1

Door casing, or trim, finishes the look of a newly installed door or can update the style of an older doorway. Care must be taken when installing casing, as the main purpose is not decorative, it is functional. Casing conceals gaps between the door jamb and the rough opening. If you are installing a new door, the casing may come mounted on one side of a pre-hung door. If you choose to replace existing trim, you will need to remove it with a pry bar and a hammer.

Step 2

Mark Door Frame for Trim

Mark Door Frame for Trim

Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

Mark Inside of Door Frame

Mark 1/4" from the inside of the door frame. This will be your guideline for installing the trim.

Step 3

Tranfer Mark on Trim to Be Installed

Tranfer Mark on Trim to Be Installed

Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

Mark Trim

Place a piece of trim on each side of the side of the door, aligned with the 1/4" mark. Transfer the mark onto the trim.

Step 4

Cut Each Piece of Door Trim to Length

Cut Each Piece of Door Trim to Length

Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

Cut Each Piece

Cut each piece to length, mitering each end at 45 degrees.

Step 5

Nail Door Side Casing in Place

Nail Door Side Casing in Place

Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

Attach Side Casings

Nail each side casing in place, starting at the top.

Step 6

Mark and Cut Top Piece of Trim to Length

Mark and Cut Top Piece of Trim to Length

Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

Mark and Cut Top Piece

Mark and cut the top piece to length, mitering each end. The most important part of installing door casing is making sure that you cut the miters so that they fit together at the corners. Some DIYers choose to install the top piece first, making sure it is level and on the mark, before installing each side piece. With the top in place, you can use the top miters to mark the side pieces. If you need to make adjustments, use a sanding sponge to gently remove material and shape the miter.

Step 7

Apply Line of Glue to End of Each Miter

Apply Line of Glue to End of Each Miter

Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

Apply Wood Glue

Apply a line of wood glue to the end of each miter to help secure the pieces of trim to each other.

Step 8

Nail Trim in Place Starting at Top

Nail Trim in Place Starting at Top

Photo by: DK - Do It Yourself Home Improvement ©2009 Dorling Kindersley Limited

DK - Do It Yourself Home Improvement, 2009 Dorling Kindersley Limited

Attach Trim Pieces

Starting at the top, nail the sides in place, then fasten the top piece in position. Fill the nail holes with spackle. Let dry and sand smooth.