Adding moulding to a flat door is a way to update the look of your doors, giving your flat doors a panelled door look. The project requires basic carpentry skills, necessitating the cutting and attachment of the moulding to the surface of the door. It's less expensive than replacing your flat doors however, and by taking a DIY approach, you can choose the ultimate look of your door by choosing among a wide variety of moulding types.
Remove the flat door from the doorway by unscrewing the door hinges holding it in place. Place the door flat across two sawhorses in an area where the entire face of the door is easy to access.
Remove the door hardware from the wood, including any hinges, doorknob, locks or latches.
Purchase the moulding you wish to use for your door, making sure that it's thick enough to create the appearance of a recessed door panel. Test the look of the moulding by temporarily attaching a piece to the door with masking tape.
Determine the best placement of the moulding on the door face. This is a matter of personal preference so move the panelling around on the door. Test moulding positions until you find a location that gives you the look you desire when the moulding completely frames the door face. Mark the location of the moulding around the face of the door with a carpenter's pencil, using a combination square to create level lines to make a rectangular frame on the face of the door.
Cut the moulding to fit the marked frame of the door. Measure the frame dimensions and cut the moulding, using a mitre box to angle the edges of the moulding 45-degrees to fit around the face of the door. Sand the cut edges of the moulding.
Paint or stain the moulding to fit the paint or stain used for the door. Apply the paint or stain with a brush, working with the grain of the wood. Allow the paint or stain to dry completely for the length of time recommended by the manufacturer, and then apply a wood sealant to the moulding,. Allow the sealant to dry overnight before continuing.
Attach the moulding to the door by applying a layer of wood glue to the rear of the moulding pieces and pressing the moulding to the door face using the drawn lines as guides. Make sure the mitred edges of the moulding butt tightly together forming a solid frame against the face of the door.
Secure the moulding to the door with headless nails. Place the nails into a brad pusher, a tool containing a driving pin for punching headless nails into wood, and then use the pusher to force the nails through the moulding into the wooden door, leaving the nails sunk beneath the moulding surface.
Reinstall the door hardware and then rehang the door in the doorway. Allow the adhesive to dry completely for 72 hours.