How to Build a French Door How to Build a French Door

What You'll Need
A pair of precut , unfinished doors
4 mullions to fit the door cut-outs
Measuring tape
2 panes of glass to fit the door cut-outs
Rubberized glue
Screwdriver
Sandpaper, or electric sander
Electric drill
Door handle and hinges

French doors are a popular and stylish way of opening a room to the outdoors or dividing up space. A French door is usually a pair of doors that is made up of panes of glass fitted into frames of wood or aluminum. Although usually seen as double doors, a French door can also be hung as a single door or bi-fold. 

Step 1 – Measure the Door Frame 

Measure the door frame to make sure the new doors will fit. If you are fitting French doors to, what was, an original wall or single door, prepare the door frames and lintels beforehand. 

Step 2 – Buy the Replacement Door 

Buy an unfinished French door frame, or two single doors, with pre-cut center pieces from your local lumber store. A cut out in the center makes it easier to install the glass. You can buy a solid door but the extra carving work requires more expertise. Buy mullions from the store to fit the door. Mullions frame and hold the glass in the door. A door will need two mullions to make four light windows. You can choose to buy mullions in the same wood as the door, or different wood for contrast. 

If you are starting with a solid door, carefully plan where you will be placing the glass panes. Mark and then drill a hole along one edge. Cut the panels out with a jigsaw. Sand and clean the holes. The mullions may also need sanding to fit the door moldings correctly. 

Step 3 – Glass and Mullions

Measure the cut out centers of the doors and buy glass to fit. Choose exterior glass if the door is opening to the outside. 

Lay the door flat on your work table. Drill holes into each corner of the frame and slide the mullion into place. Apply wood glue to the holes to secure and allow the door to dry. 

Step 4 – Install the Glass

Flip the door over and glue in the glass panel with rubberized glue, allow drying for 10 minutes. Then, glue the other mullion. Repeat the procedure for the other door.

Step 5 – Attach the Hardware

Screw the hinges onto the doors. Mount the doors onto the door frames and check that they swing properly, and then fix the door handles. There are several types of French doors, be sure to choose the one that best fits the needs of your room:

  • Pocket doors slide into a wall instead of swinging on hinges; these doors are great if you don’t have much space.
  • Multifold French doors are used as a divider for wider areas.
  • Sliding French doors are useful where there is limited space, such as onto a balcony.

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