Door Casing Sizes: What to Know Before You Install New Trim

Dress up your doorway

white home with black door and a wooden porch
Photo: Lauren Edmonds / Stocksy / Adobe Stock
white home with black door and a wooden porch
Photo: Lauren Edmonds / Stocksy / Adobe Stock
Highlights
  • 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.

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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?

Door 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. 

Door casing, door molding, and door trim are typically used interchangeably, but all typically refer to the same thing. Door casing or molding is a type of trim, which is the visible piece seen around a 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.

Standard Door Casing 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 figure out what the standard size of door molding should be.

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

Door Casing Styles

Butted versus mitered door casings compared visually
Photo: ucpage / iStock / Getty Images Plus / Getty Images, Andrii Shablovskyi / iStock / Getty Images Plus / Getty Images

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.      

Door Casing Materials

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 size of your home. Consider the height of your doors first, then consider the style of your home. Your house should dictate the type of casing you choose, in terms of whether a simpler 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?

The cost to install door trim is typically around $0.60 to $1.20 per linear foot, depending on the size of the door and how ornate your casing option is. You’ll want to hire professional door installer to help to ensure the trim is uniform across all of your doors. This is a great opportunity to think of other interior door ideas, like adding an arch or a fresh coat of paint.

Frequently Asked Questions

A standard door casing is 2 1/4 inches but can be up to 3 inches or more depending on your personal style and preference. Typically wider casings are reserved for room with much higher ceilings (over 12 feet) to accommodate for the extra trim.

The most common door trim material is solid wood, whereas the most common door trim style is craftsman or minimal. Door trim can also be found in MDF or plywood, as well as a variety of styles to fit your personal preferences.

Trim and casing are often used interchangeably. They’re both technically “trim.” However, casing most often refers to material placed around a door or a window. Trim is a broader term that describes all types of trim, whether it’s used on floors, doors, windows, or ceilings.

A door frame is not the same as a door casing. A door frame is the framework surrounding the entire door that supports the area from which the door hangs. The frame is made up of multiple parts, including the door jamb, head, and sill.

Casing refers to the trim work located around the door frame. It connects the door frame to the wall with decorative trim.

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