By Paul Bianchina
In the construction of any home, there are a number of openings that are framed or cut into the walls, floors and ceilings of the structure in order to accommodate such things as windows, doors, stairways and even medicine cabinets and toilet paper holders. In construction language, these holes in the framing are known as "rough openings," and the accuracy of their size and placement is crucial.
Sizing a Rough Opening for a Door
In order for a window or other component to fit into the wall and be secured, the opening into which it fits needs to be correct. Too small, and the window won't fit into it; too large, and you either won't be able to secure the window in place, or you'll have large gaps around it that will make installation of the finished trim very difficult.
How large an opening is framed depends, obviously, on what is going into it. Some openings have standard rules of thumb that apply during framing, while others are specific to a particular component.
In the case of a prehung door, the standard framing procedure is to make the rough opening two inches wider and two inches higher than the size of the door. For example, if you were framing for a 36-inch door, the rough opening would be 38 inches wide. Most residential doors are six feet eight inches high - 80 inches - so the standard rough opening height is 82 inches.
The same standard rough opening sizes would apply to bifold doors that have a wood frame around the inside of the opening. A five-foot wide (60-inch) set of bifold doors with a wood frame would require an opening that was five-foot two-inches in width (62 inches), and the height would again be 82 inches. For bifold doors that will be going into a drywall-wrapped opening, the rough opening width should be equal to the net width of the doors - in this example, five foot even - and the rough opening width is the net door height plus approximately three-quarters of an inch, which is typically 80 ¾ inches.
For a set of bypass doors, which are doors that slide past one another horizontally on an overhead track, the openings are a little different, and again depend on whether the doors have a wood frame. For bypass doors with a wood frame, the rough opening is the net width of the doors plus one inch - 61 inches for a five-foot pair of doors - and the height would again be 82 inches.
If the bypass doors will be going into a drywall-wrapped opening, make the rough opening one inch less than the width of the doors - in this case, 59 inches - which allows for the thickness of the drywall and creates an overlap for the doors where they meet in the center. The height may vary somewhat with the size of the track, but is typically 80 ¾ inches to 81 ¾ inches high.
Another common door is the pocket door, which recesses into a frame inside the wall. When creating a rough opening for a pocket door, you want to make it twice the width of the door, plus 2 inches. So, for a two-foot six-inch (30-inch) pocket door and frame, the rough opening should be five-foot two-inches (62 inches). To allow for the track and the overhead portion of the pocket frame, the rough opening should be 84 inches high instead of the 82 used with other types of prehung doors.
Sizing a Rough Opening for a Window
As with a door, a rough opening for a window needs to be accurate, and its sizing depends on the type of window.
In general, wood windows, which consist of the window sash inside of a wooden frame, similar to a door, will require a rough opening that is two inches wider and two inches higher than the size of the window. For example, a five-foot (60 inch) wide by four-foot (48 inch) high wood window would typically require a rough opening that is 62 inches by 50 inches.
For vinyl and aluminum windows, most manufacturers instruct that the rough opening be the same size as the net size of the window. For the 60-inch by 48-inch window mentioned above, the opening size would also by 60 inches by 48 inches. The manufacturers undersize the window slightly during the manufacturing process to ensure a proper fit.
These are just guidelines, and they may not apply to all doors and windows. Prior to framing any rough opening, it's always best to either consult the manufacturer's specifications or check with your supplier to verify the correct opening sizes.
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