How to Make a Double Rabbet Door Frame

Select the lumber for the double rabbet frame, straight boards wide enough to accommodate a door on each side, typically at least 6 inches, thick enough to allow a 1/2-inch deep rabbet. Cut the jambs to length, allowing about 2 inches extra on each side to accommodate a dado joint to hold the header jamb. Cut the header board to the width of the door plus an inch to fit into a dado slot on top of each jamb..

Cut a dado or slot 1/2 inch deep and the thickness of the top jamb board across the side jambs at top of the door. Use a table saw with a dado blade to do this.

Measure the thickness of each door, typically 1 3/4 inches for an inside entry door and 1 1/2 inches for an outer entry or storm door. Set a table saw fence to one of those specific widths and set the saw blade to cut 1/2 inch deep. Rip that cut on all three boards; stop the rip on the side jambs at the bottom of the dado. Install a jointer on the table saw and run the boards through it to remove the wood between the edge of the board and the ripped line, to form a rabbet on one side.

Follow the same process to make the rabbet on the other edge of each board, so you should have three frame boards with a 1 3/4-inch notch on one side, a 1 1/2-inch notch on the other and a 2 3/4-inch ridge or stop in the center.

Assemble the frame by putting glue on each end of the header jamb and in the dado slots on the side jambs. Slip the header into the sides, use framing clamps to hold the frame square on both sides and secure the header with finishing nails driven with a hammer through the side jambs into the header ends.