What to Know Before You Install Door Casing

Justine Harrington
Updated June 17, 2022
white home with black door and a wooden porch
Photo: Lauren Edmonds / Stocksy / Adobe Stock


  • The standard width of door casing is 2 1/4 inches.

  • Door casings are either butted or mitered in style.

  • Common materials include paint-grade wood, hardwood, and MDF.

Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.

If you feel a slight draft when you walk by your front door or notice moisture around the door after a heavy rain, it likely needs some new casing that can help improve its fit and efficiency. The average cost to spruce up a door installation and replace casing is around $100 to $170. Here's everything you need to know before you begin prepping your door for new trim. 

What Is Door Casing?

Casing (also called trim) is the decorative and protective border around a door’s opening. It seals gaps between the wall and frame, and it also adds a visually appealing element to your door. 

Basic door casings are made of three separate pieces: two long pieces for the sides of the door and a shorter piece for the top.   

What Are the Standard Door Trim Sizes?

Door casings come in various sizes, but the standard width is 2 1/4 inches. Anything wider than 3 1/2 inches has to be custom-ordered. 

When you’re trying to find the right size for your door trim, it’s important to consider the size of the room and the height of your ceiling so that the trim is proportionate and has a well-balanced appearance while fitting with surround trim and crown molding. Here’s a cheat sheet to help:

Ceiling HeightTrim Size
8 – 9 ft.2 1/4 – 3 1/4 in.
9 – 11 ft.2 1/4 – 3 1/4 in.
11 – 12 ft.3 1/4 in. or more
More than 12 ft.3 1/4 in. or more

What Are the Different Styles of Casing?

Door casings come in a wide variety of styles, which fall under two general categories: butted and mitered casing. 

Butted casing consists of two side pieces connected with a wide header (at a 90-degree angle), while mitered casing consists of two side pieces connected to a header using mitered (45-degree angled) joints. Butted casing is ideal for homes with high ceilings thanks to the size of its header, and it’s also used for custom millwork.      

What Are the Different Materials Used?

Some of the most common casing materials include paint-grade wood, hardwood, and multi-density fiberboard (MDF) casing. To decide which material is best, it’s important to consider cost, the moisture level in the room, and whether or not you want to stain or paint the trim.  

Paint-Grade Casing

Paint-grade wood casing is generally made from pine and poplar, and it consists of bare wood that’s ready for a paint application. You can really customize this type of casing and add more details than you can with human-made casing materials.   

Stain-Grade Casing

Stain-grade casing is made from oak hardwood, maple, mahogany, poplar, and other kinds of hardwood. This is the best type of casing for doors that are exposed to moisture since it doesn’t warp, and it also stains well.

MDF Casing

MDF casing is made from sawdust and resin. It looks similar to a paint-grade casing, but it tends to be less expensive. MDF is prone to swelling and warping when it comes in contact with water, so it shouldn’t be used on doors exposed to moisture.

How Do I Know Which Type of Door Casing is Right for Me?

entrance porch with white door and green frame
Photo: Iriana Shiyan / Adobe Stock

Because there are so many different types of casings available, it’s helpful to narrow down your search by thinking, first and foremost, about the style of your home. Your house should dictate the type of casing you choose, in terms of whether a more simple or ornate design is best. And, when in doubt, don’t hesitate to contact a local interior trim installation professional who can answer your questions, show you samples, and help you select the right casing for your needs.

What is the Average Cost to Install Door Casing?

According to HomeAdvisor, the average cost to install door casing is around $4 per linear foot or between $100 and $170 per door. This includes the cost of materials and labor.

Need professional help with your project?
Get quotes from top-rated pros.