Prehung Door Sizes
Prehung Door Sizes. Determine door opening sizing and charts. When framing in the rough door opening, it’s important that you correctly frame the door opening to the correct size. Prehung Door sizes and rough opening sizes are very simple. All you really need to know about door sizes vs. rough openings are that rough openings are 2″ wider and 2.5″ taller than the door being installed. Note: do not take into account the door frame around the door. When it comes to the width and height of the door, only measure the door itself. The additional 2″ on the sides and 2.5″ on the top is so that if the framing is not perfect or the door frame, you will still have plenty of room for getting the door perfectly plumb and level.
1. If you have a 32″ wide rough door opening, you need to purchase a 30″ door.
2. If you purchased a door that is 2′-6″ wide then you need to frame a rough opening that is 2′-8″ wide.
You can get a custom door built to nearly any size, but the most typical doors carried at stores are standard at 2′-6″ and 3′. We recommend finding the door size you want before building the rough door opening.
Here is some additional information: http://www.ask.com/question/rough-opening-for-a-36-inch-pre-hung-door