A rough opening is the space cut out of a wall where a window or a door will eventually go. The secures the rest of the wall around the window or door so that it will have the support it needs to stay in place.
Once the window or door is put in place, a reveal will be placed over the rough opening on the outside to help keep out moisture and the walls will be finished on the interior and exterior, so the rough opening is not something that will be seen in the finished structure. The rough opening needs to be cut to the right size to accommodate that which it frames and will be surrounded by studs in a square to form a frame.
When replacing an old window in your home instead of installing in new construction, you’ll need to get down to the rough opening of the existing window in order to install a new one. If you choose a different size window, you will likely need to rebuild the rough opening of the wall to accommodate the change.
Rough openings are an important factor in every custom house plan. A home designer can provide more information about this construction element.