How to Size Rough Frame Door Openings

Rough opening for a door in an interior wall.

Whether you are adding a door to an existing wall or framing up a new wall with a door in it, you need to allow proper space in the rough frame door opening. Too much space and the trim won't cover the gap between the door jamb and the wall and too little space could result in trimming the bottom of the door or the door not fitting at all.

Things You'll Need

• Tape measure

Instructions

1. Measure the height of the door jamb. This is different than the height of the door as the door jamb extends beyond the top and bottom of the door.

2. Add 2 inches to the height of the door jamb to determine the height of the rough opening for the door. For floors that will receive wood flooring, add the thickness of the flooring to the height of the rough opening as well.

3. Measure the width of the door, including the sides of the door jamb.

4. Determine the width of the rough opening by adding 2 inches to the width of the door. For doors taller than the standard 6 foot 8 inches, add 2 1/2 inches to the width of the door. The extra room will add space to plumb the door when it is installed.