How to Build Dual-Pane French Doors

Measure the width of the inside of the door frame using a tape measure. Divide the width by 2 to find the width of each door. Measure the height of the inside of the door frame, to find the height of each door. Note the door width and door height on a piece of paper.

Cut four sheets of 3/4-inch thick plywood to the height of the door and one-quarter of the width of the door, using a circular saw. Apply wood glue to one face of two of the sheets. Press another of the plywood sheets onto each of the glued sheets, to form two 1 1/2-inch thick sheets as long as the door height and one-quarter the width of the door.

Cut four sheets of 3/4-inch thick plywood as long as the width of the door and as wide as one-eighth of the height of the door. Glue the sheets together as before, to form two 1 1/2-inch thick sheets as wide as the door and one-eighth the height of the door. Cut the ends of the the height and width sheets at a 45 degree angle, using a miter saw.

Fit the 1/2-inch pilot bearing to the router. Cut a 1/2-inch wide, 1/2-inch deep rabbet along the middle of the shorter of the two 1 1/2-inch thick edge of each of the sheets, using the router. Cut two sheets of 1/2-inch thick plywood as long as half the width of the door and 1 inch wide. Cut two sheets of 1/2-inch thick plywood as long as three-quarters of the height of the door and 1 inch wide.

Cut one sheet of 1/2-inch thick plywood as long as three-quarters of the height of the door minus 1 inch, and 1 inch wide. Fit the 1/6-inch pilot bearing to the router. Cut a 1/6-inch wide, 1/6-inch deep rabbet along the middle of one long edge of each of the 1/2-inch thick sheets, using the router. Cut a second rabbet down the opposite edge of the three-quarter-door-length-minus-1-inch sheet.

Cut the ends of each one-rabbet sheet at 45 degrees so the rabbeted edge is shorter than the non-rabbeted edge. Nail the sheet with two rabbets to the middle of one of the half-door-width rabbeted sheets, using a hammer and a 1-inch long nail. Nail the other half-door-width rabbeted sheet to the other end of the two-rabbeted sheet, to form an “I” shape.

Cut two sheets of 1/6-inch thick glass as long as three-quarters of the height of the door minus 1 inch, and as wide as one-quarter of the width of the door minus 1 inch, using a glass cutter. Slide the glass sheets into either side of the “I” shape.

Nail the remaining three-quarter-door-length sheets onto the sides of the “I” shape using a 1-inch long nail in each joint and with the glass sheets fitting into the rabbets. This forms the center frame of the door with the glass surrounded by mullions.

Fit a 1-inch diameter drill bit into the hammer drill. Drill two 1-inch deep holes into the middle of either end of both door-width 1 1/2-inch thick sheets. Cut the 1-inch diameter dowel rod into eight 2-inch long pieces, using the circular saw. Apply wood glue around the dowel pieces. Tap one of the dowel pieces into each hole in the 1 1/2-inch thick sheets, using a hammer.

Hold one of the door-height 1 1/2-inch thick sheets to either end of the door-width sheets. Mark on the door-height sheets the points where the dowel pieces touch the door-height sheets, using a pencil. Drill a 1-inch deep hole at each marked point on both sheets. Tap the door-height sheets onto the dowel pieces on one of the door-width pieces using a hammer, until the sheets are half way on to the dowels.

Slide the center frame into the rabbets on the door-height sheets until the mullion at the top of the center piece fits into the rabbet in the door-width piece. Tap the center piece snugly into place carefully, using light taps with the hammer. Fit the second door-width piece onto the bottom of the door frame. Tap the door-height pieces fully onto the dowels at the top and bottom of the door.