How to Update a Flat Interior Door

Written by tyliee
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How to Update a Flat Interior Door
Moulding is a strong feature of this doorway. (the door image by Zbigniew Nowak from

Gone are the days of the flat panel door. Not only are they outdated, but they can look cheap when surrounded by a modernised setting. The good news is that standard flat panel doors can be both dressed up and updated by simply adding some moulding. This project is a quick and easy way to bring old doors into the current era and add some customisation, depth and class to any doorway.

Skill level:

Things you need

  • Damp rag
  • Tape measure
  • Pencil
  • Protractor
  • Decorative moulding
  • Hand saw
  • Mitre box
  • Stain or paint to match door
  • Wood glue
  • Level
  • Trim nails
  • Pneumatic nail gun

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  1. 1

    Wipe down the surface of your interior door and use your tape measure to determine where you'd like your moulding border to be positioned. Use your pencil to mark the height and width of your desired shape. Simple rectangles are most suitable for first-time designers. Mark the spots where each of your four angles will converge. The size of your door and your personal preference will determine the width and height of your moulding.

  2. 2

    Use your pencil to transfer the measurements onto your moulding. Use your protractor to draw 45-degree angles that correspond to each of your measurements. Remember, that two 45-degree angles make a 90-degree angle. Your moulding rectangle will require four 90-degree angles, which translates to eight 45-degree angles.

    How to Update a Flat Interior Door
    Protractors are useful for marking angles. (protractor image by timur1970 from
  3. 3

    Use your hand saw and mitre box to cut out your angles. Try to visualise how each cut will fit together as you make your cuts. It's important that your mitre cuts are accurate. Your moulding will not fit snugly together if your cuts are off. You should be left with four pieces of moulding, two long and two short. The two long pieces should be the same length, as should the two short pieces.

    How to Update a Flat Interior Door
    This project is easily completed with a hand saw. (sawing wood image by Aussiebloke from
  4. 4

    Stain or paint your moulding to match the door in question. Allow the paint or stain to dry completely.

  5. 5

    Apply a thin bead of wood glue to the back of one piece of moulding. Apply the glued piece of moulding to the door using your pencil marks as a guide. Use your level to ensure a perfectly vertical application and secure the trim piece to the door using the trim nails and pneumatic nail gun. Nail the piece at points two inches from the top and two inches from the bottom, with one nail in the middle. Repeat the process of gluing and nailing for all four of your trim pieces.

    How to Update a Flat Interior Door
    Trim nails complete the job of attaching the moulding to the door. (nails image by Witold Krasowski from

Tips and warnings

  • If you're adding moulding to more than one door, you should use the same measurements for each door to ensure a uniform look to all your doors.
  • Use caution when using tools of any sort, to avoid injury.

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