Plain hollow core doors are often made of a veneer plywood exterior. The wood is not solid all the way through the door. This type of door doesn't muffle the sound inside a room as well as a solid door, and often, they are plain and unattractive. One way to update the door is by applying a moulding to the door to suggest a raised panel or several raised panels. This is not a difficult project and the payoff in improved appearance is worth the effort.
Remove your hollow interior door by driving the pins up out of the door hinges, using a hammer and flat-edged screwdriver and lifting the door. Place the door on sawhorses or a work table. Remove the doorknob with a screwdriver. This will make the door easier to sand and finish.
Sand the door to remove the finish using an orbital sander and medium-grit (60- to 80-grit) sandpaper. The disk of an orbital sander spins in a circular motion, while the pad moves in an oval loop. This unusual motion leaves a swirl-free finish. Use a medium- to heavy- grit sandpaper as the motion of the sander is not as aggressive as a belt sander.
Look at images of panel doors. Most colonial-type doors (traditional style) will have six separate panels. Two small panels at the top and four larger panels lower on the door. Select the panel style that you want to use. One good way to figure out the look and measurements is to visit the home improvement store and look at and measure the panels on the same size of door as your door.
Transfer your measurements to the door. Draw straight lines with a straight edge and tape measure. Your lines should represent the inside or outside of your moulding edges. Either measurement will work as long as you remember which edge you are using for your project.
Measure the width of your top panel horizontal line. Transfer this measurement to your moulding and mark your moulding. Cut your moulding using a mitre saw or mitre box and fine toothed saw. A mitre is a 45-degree angle cut. When you put two mitred corners together they form a 90-degree angle. Each of your mouldings will have two opposing mitre cuts so that when you put your mouldings together they form a rectangle with tight corners.
Cut your first moulding and hold the moulding to the door to see how it lines up. The pointed ends of the moulding should be at the top and the shallow angle should be at the bottom or inside. If the moulding fits and looks correct, cut as many of that size as you need. Most traditional panel styles will use 12 pieces at this size.
Measure the height of each panel and cut two pieces with mitred ends per panel. Layout your mouldings against your drawn lines on the door. You should see the panel arrangement you selected. Apply a bead of carpenter's glue to the back of each piece and glue the mouldings to the door. If the pieces don't want to stay in place, tape across the corner joint with painter's tape, making sure they are aligned well. Often, brads will not hold in hollow doors, so you must rely more heavily on the glue. Panel the other side of the door once the first side dries completely or at least for 24 hours.
Wood fill, sand, prime and paint your doors. Caulk around the edges for clean seams.
Panel all of the doors in your home at the same time so that the look is consistent throughout the house. This also makes calculating your panels easier. Remember that narrower doors will have narrower or fewer panels than wider doors.
Always paint in a well-ventilated area.