A standard interior door in a typical home is a hollow door, featuring a single piece of wood with one doorknob and a hollow core to prevent the wood from being too heavy to manipulate easily. A Dutch door, on the other hand, has both a top section and a bottom section, each built with a hollow core. These doors have two sets of doorknobs to correspond to the two different parts of the door.
Dutch doors are unique in a home and are useful for people who like to be able to regulate the light or space that can be seen through a doorway or to limit access to another room without completely closing it off. If you wish to keep the door entirely open or closed you may, but you can also open up solely the top half of the door or the bottom half if you would like to further adjust the atmosphere in a room. The process of converting a hollow door to a Dutch door is straightforward, but it will require a fair amount of time and effort.
Step 1 - Measure and mark at the desired height
After you've gathered all of the necessary materials and tools to begin the project, measure the height of the door, and make a mark halfway down the length of it. If you wish to cut your Dutch door at a different height, you can notate the cut line at this time to your preference. A good height is around 38-inches which is a normal handrail height. Be sure to mark both sides of the door, and then use your measuring tape and a pencil to draw a straight line across the width of the door to serve as a guide for your cutting.
Step 2 - Cut and sand the door
Make sure to wear safety glasses while using a power saw. Cut the door on the line that you've marked using your saw. Once you've cut the door, sand down the edges to remove splinters or any other roughness.
Step 3 - Cut and secure your filler
Make 2 fillers from new lumber at the same thickness as the space width inside the door, and long enough to fit in-between the filler stiles inside the door. The width of the fillers to be inserted inside can be 2 to 4-inches, the wider providing more stability. Insert each filler into their respective door openings keeping them flush with the cut edge. You can then spread apart the plywood from each side of the doors and squirt plenty of wood glue in-between and on each side to get good adhesion. Use a few spring clamps or screw clamps along the glued edges to ensure a proper setting.
With that completed, sand or plane the top edge of the bottom sash to get a straight, true, and smooth surface. To give it a cleaner look, you can also add a 1/4-inch band or strip of wood on top of the bottom part to hide the underlying construction. This will help to give your door a smooth, professional appearance.
Step 4 - Add a doorknob and hinges
The final step necessary to convert your door is to add a doorknob on the second portion of the door. Follow the doorknob installation instructions, and make sure that the knob is placed level with the other existing one. Next, you'll need to make sure that each half of the new door has two hinges. Measure them out and attach them to the door and to the door frame on the wall as well.