How to Frame a Doorway for a French Door

When framing a doorway for a French door, the frame will hold two doors and not just one. Therefore, the measurements need to be exact. You need a few calculations to determine the exact measurements of the frame to accommodate the two French doors. Instead of two gaps between the frame and the door, as with a single door, you'll need to account for three gaps in the measurement of the French door frame. In addition, the measurements need to account for the door jamb and side plate.

Measuring tape
Carpenter pencil
Level
Carpenter square
Framing square
Saw (circular saw works best)
2-by-4 boards
2-by-6 boards
1/4-inch plywood
Framing nails

Instructions

- 1
  Measure the width of the French doors. Add the following measurements to account for the three gaps and the door jamb: 1/4 inch times 3 for the gaps, plus 1 1/4 inch for the door jamb and side plate. The formula for measurement of the width of the French door frame is: (width of both doors) + 3/4 inch + 1 1/4 inch.
- 2
  Measure the height of the French doors. Add the following measurements to account for the top space between the doors and the jamb, as well as the space between the doors and the floor: 1 inch for the space between door and floor plus 2 inches for the space between the top jamb and the top of the French doors. The formula for measurement of the height of the French door frame is: (height of doors) + 1 inch + 2 inches.
- 3
  Mark the 2-by-4s according to the width and height measurements gathered in the first two steps. Mark two of the 2-by-4s with the height measurements, and cut one of the 2-by-4s using the width measurements.
- 4
  Cut the 2-by-4s at the measurement markings using the saw. The end result will be two long pieces of 2-by-4 for each side of the door frame, and one short piece for the top of the frame. Use these pieces for the inner portion of the frame.
- 5
  Measure from the floor to the top of the doorway for the width of the unfinished doorway space. Measure from side to side for the width of the unfinished doorway. Cut 2-by-4s according to these measurements with the saw for the outer portion of the frame.
- 6
  Nail the outer height cut 2-by-4s for the outer frame to the top and bottom doorway plates using framing nails.
- 7
  Use the level to locate a space on the top plate on one side of the frame that is level. Nail the top 2-by-4 piece to the leveled spot. Repeat the process for the other side of the top plate.
- 8
  Construct the header piece by measuring and cutting two 2-by-6 wood pieces, and one piece of plywood according to the width measurements taken in Step 1. Nail the header in place by attaching it to each side of the two vertical 2-by-4s that make up the outer portion of the door frame.
- 9
  Nail the 2-by-4s measured and cut for the inner portion of the door frame (the pieces cut in Step 4) to the outer vertical 2-by-4s with framing nails.
- 10
  Nail the measured and cut top inner 2-by-4 to the top of the outer frame. The frame for the French door set is now in place.
- 11
  Install the French door set using the same spacing measurements used to measure for the inner portion of the frame.

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