How to Paint Interior Window Trim

Painting interior window trim

The Spruce / Margot Cavin

Project Overview
  • Working Time: 3 hrs
  • Total Time: 8 hrs
  • Skill Level: Beginner
  • Estimated Cost: $50

Painting window or door interior trim is one secret to freshening up a room with little cost or effort. There are two main reasons why you may want to paint your interior trim—the first being that you have existing trim that has become beaten-up, dinged, and discolored over the years. The other common scenario is that you have installed trim that is primed but unpainted and is in need of the finishing coat. In either case, the painting process requires about the same amount of work.

Supplies needed to paint interior window trim
The Spruce / Margot Cavin

What You'll Need

Equipment / Tools

  • 1 2-inch trim paintbrush
  • Scissors
  • Putty knife (if needed)
  • Utility knife (if needed)


  • 1 Roll of 1.5-inch painter's tape
  • 1 Interior trim paint (appropriate amount for your project)
  • 1 Tube of wood filler
  • 1 Sheet of 220-grit sandpaper
  • Primer
  • Wood filler (if needed)


  1. Tape One Side of the Interior of the Trim

    Mask the window at the juncture of the window frame and trim.

    Rip off a section of painter's tape about 1/3 the length of the section you will be taping. In this example, the section is 34 inches long, so the piece of tape used is roughly 11 inches long.

    Use scissors to cut one end of the painter's tape at a 45-degree angle. Because you will need some overlap, it doesn't hurt to cut it a bit past 45 degrees. Apply to the window frame as shown.


    You can create sharp edges either by "cutting in" or by using painter's masking tape. Cutting-in means you trade the masking tape for a steady, practiced hand. Pro painters like the cut-in method. Masking is the opposite: you mask out the areas you don't want to be painted. Once the masking is complete, you don't have to worry about being careful: the masking tape does the work of creating lines.

    Tape one side of interior trim
    The Spruce / Margot Cavin
  2. Repeat the Taping on the Right Side

    Now tape the right side of the window frame in the same fashion as before.

    Tape right side of trim interior
    The Spruce / Margot Cavin
  3. Fill in the Middle Sections With Masking Tape

    Between those two end pieces of tape, you've got a gap. Fill it in with the third piece of tape. There's no need to cut the ends in any special fashion; just rip it with your fingers.


    Breaking up your taping into smaller sections gives you better control of the tape than if you used single long strips. Experts from Glidden Paints recommend a length no longer than from your wrist to your elbow.

    Tape bottom of interior window trim
    The Spruce / Margot Cavin
  4. Mask Off the Wall Around the Window Trim

    Run a strip of masking tape about 4 inches longer than the trim you are masking. Center it so that you have about 2 inches extra on both ends. Apply to the wall.

    Now run another strip of the perpendicular trim, making sure that the two ends overlap.

    Tape wall around window trim
    The Spruce / Margot Cavin
  5. Fill in Any Holes and Prime the Window Trim (Optional)

    You might have holes in the wood that need filling. Apply wood filler to the holes, let dry, and then sand flat.


    Watch Now: How to Fill Nail Holes in Trim

    If you have bare patches of wood that need priming before painting, apply primer, let dry, and then assess. If the areas are not completely white with primer, paint them again.

    Fill in window trim holes
    The Spruce / Margot Cavin
  6. Paint the Inside Sections of Window Trim

    Begin with painting the trim closest to the window. If you paint the outer, room-facing section of the trim first, you may accidentally smudge the paint with your hand when moving to the inside part.

    Paint inside window trim
    The Spruce / Margot Cavin
  7. Paint the Parts of the Trim That Face the Room

    Now paint the part of the trim that faces the room.

    Because you've got masking tape applied, you can run the brush right over the tape (just don't go beyond it).

    Be careful not to slop too much paint over the tape. Otherwise, you may not be able to "cut" the paint after it has dried.

    Paint window trim that faces room
    The Spruce / Margot Cavin
  8. Remove the Painter's Tape From the Window Trim

    Let the paint thoroughly dry. Remove the painter's tape only after the paint is dry. Do not try to remove the tape while wet.

    Peel the tape away in a smooth, constant motion. The tape is strong enough to slice through one or even two layers of paint (beyond that, the tape itself might tear).

    If the tape does not cleanly cut through the paint, use a sharp utility knife to cut away the spots left behind.

    Remove painter's tape from window trim
    The Spruce / Margot Cavin

Should You Paint Before or After Installation?

If you're adding new trim, you can choose to first paint the loose materials first, or wait to paint once the trim is installed.

It's easy to spread out multiple lengths of window trim on the drop cloth outside and paint all of the moldings in one bunch, but there are two problems with this approach. First, with the trim in that position, you will get a lot of drops that stick to the newspaper. Second, your good work will inevitably get ruined (to some degree or another) by your cutting and nailing—no matter how hard you try to be careful.

In the end, painting window trim before cutting does not save you much time. But it does help to buy primed window trim or to prime the window trim yourself before cutting and installation.

Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. How To Use Painters Tape. Glidden Paints, PPG Industries.