How to Measure for Your Barn Door Installation Project

How to Measure for Your Barn Door Installation Project

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How big should my barn door be?

When buying a sliding barn door, a prevalent question is: how tall and wide should my barn door be? Most people do not know that measuring your door frame for a barn door is different from measuring for a regular swing door.

You will need a different size for a sliding door versus a traditional swinging door in the same size opening. 

Unlike swinging doors, where the door has to exactly fit the door frame, with barn doors, you will need a slightly larger door than the opening. Why? Because if you have a door that is the exact same size as the opening, you will have lots of light and sound coming through the edges of the door. And if your opening is irregular, it will be evident when the door is closed.


Consider Privacy

As mentioned before, it is essential to make the d

As mentioned before, it is essential to make the door overlap the opening to ensure privacy and aesthetics. We recommend adding at least one inch overlap on each side of the opening or molding. The more overlap you have, the less light and sound will come through the edges. 


Need more explanation? Casing or No Casing That is the question?

First you need to determine whether or not there is casing (often referred to as trim) around your opening or if it is simply a sheetrocked door opening.  This is the most important detail to get started as it will affect the size of your barn door.  It is possible that your opening has been sheetrocked all the way around and does not have a jamb or casing.  This is very common in new construction. Below are a couple images of each instance that illustrate the difference between a sheetrocked or cased opening.

Measuring Door Width

Measuring door width is important to make sure that your door fully covers the door opening, and provides adequate privacy.

With Molding

If your door opening has molding, you will need to purchase a door wide enough to cover the molding. To measure the width, use a measuring tape, and measure horizontally from the outside edge of the molding, to the outside edge on the other side of the door. 

This is the minimum measurement, but you can choose to go wider for a different look. Just keep in mind that this will require more wall space and extra track length (we will discuss how to measure for these later).

Certain types of moldings may not be compatible with sliding barn doors. The molding must stick out less than 1” from the wall. If you have a decorative molding that sticks out further, you won’t be able to properly install a sliding barn door. Why? The thicker molding requires the door to be spaced out further from the wall, which creates a much larger gap and eliminates privacy. Not only is this less functional, but it is much less aesthetically pleasing.

Without Molding

If there is no molding, measure the horizontal width of the door opening and add 2-4” of width – this is your minimum width measurement for door openings without molding. Why add width? Because there is a gap between the door and the wall, and the extra width gets rid of that space and eliminates the sight line, adding privacy. When a door opening has molding around it, the molding does the job of eliminating the gap and blocking the sight line.

How to Measure for a Traditional Hinged Door

1. Measure the Door Slab

The first thing you’ll want to measure is the door slab. The door slab is the actual door without the frame or hardware. You’ll need to measure the height, width, and thickness of the door. Your new door slab needs to be the same exact size, or at least trimmable to the exact size.To measure your door, you’ll need to grab your measuring tape so you can get the measurements you need. The process will be the same whether you are measuring for an interior door or an exterior door. Measure the slab from the ‘inside’ which is the side with the hinges.How to measure a door slab:To measure your door slab, you’ll want to open the door and measure the actual panel that swings. To ensure you have the most accurate measurements, measure the door slab from the interior side. This means measuring the side of the door slab with the hinges. 
  • Measure the door width. Do this by measuring from the left to the right side of the door. The average door width ranges from 24-inches to 36-inches. Exterior door sizes may even be larger. 
  • Measure the door height. Using your measuring tape, measure from the top of the door to the bottom of the door. The average door height is a minimum of 80-inches. 
  • Measure the thickness of the door. Do this by measuring from the front to the back of the door. The standard door thickness is 1 ¾ inch. 
If you are replacing only the door slab and do not intend to replace the frame, you have all the information you need to select a new door slab.  If you intend to purchase a prehung door, this means you are replacing the door and the frame, as those two pieces are purchased preassembled.  You will need further measurements to ensure you purchase the right setup. 

2. Remove the Trim

Trim is an added decorative piece to frame the door and gives it a polished and complete look. This means that it is relatively easy to remove. To remove your trim all you’ll need is a pry bar and a bit of patience. If done gently you can reuse the trim without having to replace it. When you remove the trim, you’ll be able to see the wooden frame. This will help you make more accurate measurements. You’ll want to remove the trim whether you are measuring for an interior or exterior door. However, note that when you are measuring for an exterior door, you’ll want to remove both the interior trim and the exterior trim. 

3. Measure the Frame Size

Once you know the size of your door slab and you’ve removed the trim, you need to measure the size of the door frame. The door frame is the wooden frame that surrounds the door slab. The hinges for the door slab attach to the frame when hanging the door. Measuring the door frame is especially important if you are looking to install a prehung interior or prehung exterior door.  How to measure a door frame:Just as with the door slab, several measurements must be taken. You’ll want to stand in the door opening to take the measurements for the door frame. This is true for both interior and exterior doors. 
  • Measure the frame height. When you measure frame height, be sure to do it from the middle of the frame. Do this by measuring from the bottom inside edge of the door frame to the floor. 
  • Measure the frame width. Measure the width of the frame by measuring from the inside edge of the left side to the inside edge of the right side of the frame. Be sure to measure in a few different places and go with the smallest measurement. 
  • Measure the door jamb. This requires measuring the depth wooden frame that holds the door from front to back.

4. Measure the Rough Opening

When you are replacing a door, you need to know exactly how much space you have to work with, so the new frame will fit inside the opening. The best way to figure out how much space you have is to measure the rough opening. You can get this measurement by removing the frame entirely. You’ll need the measurement for the rough opening whether you are installing a barn door, a single door, or double doors. If you are replacing your exterior door and you have sidelights, you need to decide if you want to keep your existing ones or if you’ll be replacing them. If you decide to keep them, you do not need to include them in your rough opening measurements. However, if you choose to replace them, then you’ll also need to account for the length and width of your sidelights you are replacing. How to measure a rough opening: Measuring for a rough opening means measuring the entire opening you have in the wall for the door. Before you measure for a rough opening make sure the door slab, trim, and frame have been removed. 
  • Measure the rough opening height. To get the height measurement, you’ll want to stand in the middle of the opening and measure from top to bottom. 
  • Measure the rough opening width. To get the width measurement, you’ll want to measure from one side of the opening to the other. It is helpful to take this in a couple of different places as there can be slight variance with the opening being smaller in some areas and larger in others. 
  • Measure the rough opening depth. Getting the depth measurement of the rough opening is important to make sure the frame you get is not too deep. If the frame is too deep it will protrude from the wall. 

Trimmed or Cased Opening

  1. Width: In instances where casing is present we recommend building the door to the same size as the opening + casing.  Measure from the outside of the casing to the outside of the casing for the door width.  (In this example the total width is 38″).
  2. Height: For the door height we recommend measuring from the floor to the top of the casing.  (In this example the total height is 83″)

When closed (over the opening) the door will cover

When closed (over the opening) the door will cover all of the casing for a cohesive look.  The graphic below simulated a door over the opening.

**TIP: In order to slide, we recommend mounting the door 1″ above the finished floor.  This will ensure you have room to mount a door guide under the door without friction issues.

Sheetrocked Opening (No Trim or Casing)

Sheetrocked Opening (No Trim or Casing)

  1. Width: Measure from inside to inside of the opening. Add 4″ to the measurement and you have your recommended door width.   (In this example the opening width is 32″ +4″).  Total door width will be 36″

Why add 4″? The door will need to hang off the wall a couple of inches in order to slide.  As a result, the door must be wider than the opening to eliminate sightlines from angles around the opening.  In the example above involving casing, the casing already ‘frames’ the door and adds 4-6 inches of width to the door that will generously cover the opening.  For sheetrocked openings you want to add the extra door width to accomplish the same result.

2. For the door height we recommend measuring from the floor to the top of the opening.  (In this example the total height is 80″)

Once mounted the door will hang ~1″ off the floor which will add the bit of coverage you need at the top of the opening.

**TIP: Once you’ve established your desired

**TIP: Once you’ve established your desired door size.  Double check to make sure you still have enough space for the full door to slide out of the way.

Depending on the style of the door, don’t forget to note which way your new sliding barn door will slide.  This may affect how the door is built as well as the handle location.

How do I order a door for my home or business?

How do I order a door for my home or business?

  1. The first step is to use the photos and measuring tips outlined in this post to get started, feel free to visit our portfolio of sliding doors for more inspiration.
  2. Next, jump over to our custom orders page and tell us about your project.  The most important details to include will be opening dimensions, which door application you have in mind, and maybe even a photo or two of the space.  Our custom orders page has a place to attach your photos.  Once we have the details we’ll circle back with an email and some pricing.  This is the most efficient way to get in contact to ensure we have all your project details in one place.
  3. Once the details are finalized we’ll handle the dirty work and then circle back when your door is ready.  We also offer installation and will handle as much of the project as you find necessary.


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