If you’re installing new interior doors, it’s important to measure the interior door’s rough opening size. While there are standard door opening measurements, not all openings will adhere to these numbers. This step-by-step guide explains how to measure rough openings, so you save time and money when purchasing your new interior door.
What Are Standard Sizes for Interior Door Rough Openings?
Interior door rough openings come in various sizes depending on the type of door the homeowner is installing. While there are standard measurements, these can vary slightly based on the manufacturer and specific door design.
Single Door Rough Openings
For a single interior door, the rough opening should be 2 inches wider and 2.5 inches taller than the actual door size. For example, if the door measures 30 inches wide by 80 inches tall (commonly referred to as a 2/6 x 6/8 door), the rough opening should be 32 inches wide and 82.5 inches tall.
Double-Door Rough Openings
Double-door units follow a similar rule to single doors. The rough opening should be 2 inches wider than the combined width of both doors and 2.5 inches taller than the door height. For instance, a set of double doors measuring 60 inches wide by 80 inches tall would require a rough opening of 62 inches wide by 82.5 inches tall.
French Door Rough Openings
French doors require a slightly different calculation. To determine the width of the rough opening, measure one door. Multiply the door width by two and then add 2 inches. For the height, simply add 2.5 inches. So, for a 30-inch wide by an 80-inch tall French door, the rough opening should measure 62 inches wide by 82.5 inches tall.
Sliding Door Rough Openings
Sliding doors are unique in that they don’t require a specific formula for calculating the rough opening. Instead, homeowners should measure the actual opening where the door will be installed, from stud to stud for width and from the bottom plate to the header for height.
Pocket Door Rough Openings
Pocket doors are a space-saving solution, as they slide into a compartment within the wall instead of swinging open. For these doors, the rough opening needs to accommodate the door itself and the frame housing. Typically, the rough opening width will be twice the door width plus 1 inch. To compute the height, add 2 inches to the door height. For instance, a 30-inch wide by 80-inch tall pocket door would need a rough opening of 61 inches wide by 82.5 inches tall.
How Do You Measure Indoor Door Rough Openings?
Accurately measuring the rough opening will help you purchase the correct interior door for your home. Here’s a step-by-step guide to help homeowners get it right:
Step 1: Measure the Width
Using a tape measure, measure the distance between the studs at the widest point of the opening. Take measurements at the top, middle, and bottom of the opening, as older homes may have settled, causing slight variations. Use the largest measurement to make sure the door will fit.
Step 2: Measure the Height
Measure from the floor (or bottom plate) to the underside of the header at both sides of the opening. Take multiple measurements and use the largest one to account for any unevenness.
Step 3: Check for Square
To check if the opening is square, measure diagonally from corner to corner in both directions. If the measurements are equal, the opening is square. If not, you may need to make adjustments or choose a door that can accommodate the discrepancy.
Step 4: Consider the Flooring
If you’re planning to install new floors, factor in its thickness when measuring the height. This allows the door to clear the new floor surface once installed.
Step 5: Evaluate the Wall Thickness
Assess the thickness of the wall framing. Typically, modern interior walls are framed with 2 x 4 or 2 x 6 studs, which can affect the choice of door jambs and the overall installation process.
Standard Sizes for Interior Doors
Standard door sizes can help homeowners choose the right door for their rough opening.
- Standard interior door widths include 2/6 (30 inches), 2/8 (32 inches), and 3/0 (36 inches).
- Standard interior door heights are 6/6 (78 inches) and 6/8 (80 inches).
- Bi-fold doors range from 24 to 36 inches in width per panel.
While these are the most common sizes, homeowners can also order custom doors for nonstandard openings or to meet specific design preferences.
Tips for the Perfect Fit
Getting the right fit for an interior door involves more than just measuring the rough opening. Here are some additional tips to keep in mind:
- Allow for shims. The rough opening should be larger than the door frame to allow for shims. These thin pieces of wood help level and plumb the door during installation.
- Consider the jamb width. The jamb width, which is the depth of the door frame, should match the thickness of the wall. Standard jamb widths are 4 9/16 inches for 2 x 4 wall construction and 6 9/16 inches for 2 x 6 walls.
- Check building codes. Some local building codes may have specific requirements for door sizes, especially for bedrooms or bathrooms.
- Verify the door swing. Determine the door’s swing direction (inward or outward) before installation. This can impact a room’s layout and space.
- Measure more than once. “Measure twice, cut once” is always good advice. Measurement mistakes can result in costly corrections.
- Account for the threshold. For doors leading to areas with different flooring heights, such as a bathroom, remember to account for any threshold that may be needed.
- Inspect the existing door frame. If the frame is warped, damaged, or not level, it could complicate the installation of the new door. You may have to replace the frame.
- Check wall alignments. Walls aren’t always perfectly straight. Evaluating their alignment with the door can prevent unexpected gaps.
When to Seek Professional Help
While determining an interior door rough opening size is often a DIY task, there are situations where professional assistance may be beneficial if the opening is significantly out of square or level, you’re dealing with load-bearing walls, or you’re faced with complex door installations. Local building codes and permit requirements can also be confusing, so it can be helpful to go with a professional installer if you’re unsure about these regulations.
Final Thoughts About Interior Door Rough Opening Sizes
By understanding standard sizes, following proper measurement techniques, and considering factors like shims and flooring, homeowners can select the right door for the job on their first trip to the home improvement store. Reach out to a professional if you think there will be problems when installing your new door.
