Getting the rough opening size right the first time, will save you from frustration, when installing your doors. Framing rough opening sizes are really quite simple. Just add 2″ to the width of the actual door size. You should add 2-1/2″ to the height of the actual door.
The standard height of the rough opening for a door is the door height plus 2 5/8 inches. The additional room allows for a 3/4-inch top jamb, a shim space above the door jamb, and the thickness of underlayment and finishes flooring. Standard door heights are 6/6 (78”) and 6/8 (80”).
While 80 inches is the norm, taller doors — 84 or even 96 inches — are common in modern or high-ceiling homes.
For a Single door, the rough opening should be 2-1/2 inches wider and 2 inches taller than the nominal dimensions of the door slab you measured earlier. Example: If you have a 36 x 80 door, your rough opening should be 38-1/2" wide x 82" tall.
So, if you have a bedroom door that is 30″ wide (which is considered a 2/6 or 2′-6″ door) just add 2″ to the width and frame it 32″ wide.
Add 10mm to the door height to get the reveal height. Add 48mm to the door height to get the overall height. Subtract 30mm from the reveal width to get the clear opening width. Subtract 15mm from the reveal height to get the clear opening height.
Standard Rough Opening Sizes
The way this is determined is, take the desired pre-hung door size (door size not including the frame) and simply add 2" to the width and roughly 2.5" to the height. That's it. This extra 2" gives room for the door's frame as well as a little extra play for getting the door perfect.
If the opening is really wide consider adding a 2x4 to the rough opening or buy another door that fits the frame. If it's way too big of an opening, you need to frame it in smaller. However if it is less than say an inch, you can center it in the hole and shim both sides in and trim it out afterwards.
To comply with ADA guidelines, doorways should have a minimum clear width of 32 inches when the door is open to 90 degrees. This width is essential for individuals using mobility aids to pass through without obstruction.
Code generally requires interior standard door sizes to have a certain height. It needs to be a minimum of 80 inches (although some codes allow for 78 inch doors).
Opening Height is the nominal height of the individual door opening.
The standard rough opening for a closet door typically measures 80 inches in height and 30 inches in width, which accommodates a standard 28-inch wide door. For double doors, the width can range from 60 to 72 inches.
While homes come in all shapes and styles, most entry doors follow some common measurements. The most typical standard door width is 36 inches, paired with a height of 80 inches. However, don't worry if your measurements differ — standard door sizes can range from: Width: 30 to 45 inches.
Measuring Door Size
Measure the width of the rough opening, from inside of wall stud to inside of wall stud (see the illustration for this measurement). Measure this in three places—the top, middle, and bottom of the opening, and then use the smallest of these three measurements.
The standard size for a door frame is 80 inches by 36 inches, with the rough opening slightly larger at 82 inches by 38 inches. This standard size can vary depending on how tall are standard doors, the type of door, as well as the specific measurements of your home.
In conclusion, a 30-inch door is precisely 30 inches wide in terms of the door slab. However, when installing it, you will need to consider the framed opening, clearance requirements, swing, and other factors to ensure that the door fits snugly and operates correctly.
The rough height of the door openings are the height of the doors PLUS 2-1/2" [3/4" for the jamb PLUS 1-1/4" for flooring PLUS 1/2" for leveling]. So using the information above, AS AN EXAMPLE, a door that is 32" wide and 96" tall requires a rough opening 34" wide x 98-1/2" tall!
Door widths vary, but an easy way to size the rough opening is to use the door width plus 5 in. as the distance between the king studs. There are three simple rules to framing rough openings efficiently: Minimize layout marks; maintain a simple, consistent nailing pattern; and avoid toenailing when possible.
There should be a 2mm or 3mm gap between the door and the frame on both sides and the top. If you do need to cut the door down to size, keep in mind that you need to cut all four sides of the door equally whenever possible to retain an accurate shape or pattern if the door is panelled.
That means a 32x80 inch door needs a 34x82 inch opening.
Standard Size for Closet and Utility Doors
In houses built before 1990's the doors could be as narrow as 18 inches. Newer comes usually have a width of 30 inches and a standard high of 96” inches.