Paint Interior Window Trim and Spruce Up a Room

Man Holding a Paint Tin and a Paintbrush, Painting a Window Frame
Alex Wilson / Getty Images

Painting window or door interior trim is one secret to freshening up a room with little cost or effort.

You might have existing trim that has become beaten-up, dinged, and discolored over the years. Or, as part of a remodeling project, you might have installed trim that is primed but unpainted.

In either case, the painting process is about the same.

Personally, I find trim-painting to be a wholly satisfying home remodeling project. It's a precise job and you are rewarded by shiny, smooth new trim work. Give it a try!

Should You Paint Before or After Installation?

This article deals with trim that is already installed and in place. But I want to add a section in case you are vacillating about whether to install before painting or to first paint the loose materials before installing.

There are two schools of thought about this.

It is easy to lay 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.

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.

One favorite guide for tips about dealing with window trim is the Black & Decker Complete Guide to Windows & Entryways. You will find lots of clear graphics and just enough text to steer you along. 

Buy on Amazon - Black & Decker Complete Guide to Windows & Entryways

Your Materials

The great thing about this project is that the materials are few and cheap. You can paint an entire room's trim for under $40. For a whole house, your outlay might be $100-$150, probably far less.

  • Painter's Tape. Scotch-Blue™ pulls off better than other brands I've used, and seepage under the tape is non-existent when applied correctly. Get 1 1/2" wide or wider.
  • 1 1/2" to 2" Trim Paint Brush. The bristles of a trim brush have a wedge shape, making the brush easier to get into tight spaces. 
  • Interior Trim Paint. Purchase paint that is specifically titled as "trim paint" or an interior paint that lists within its specs usage on trim, cabinets, doors, windows, etc. 
  • Optional: Wood Filler and Sandpaper. Buy wood filler capable of being sanded, stained, and painted (labels usually specify all three uses). You do not want to get the wax-type wood filler used for furniture; this cannot be painted. (Compare Prices - Elmer's Stainable Wood Filler). For sandpaper, choose a fine 220 grit.


Tape One Side of Interior of Trim

Tape Inside Left Trim
Lee Wallender

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. I prefer to mask. Once the masking is complete, I don't have to worry about being careful: the masking tape does the work of creating lines.

Begin Taping

First, you want to mask the window at the juncture of the window frame and trim.

  • Rip off a section of painter's tape about 1/3rd the length of the section you will be taping. In our example, the section is 34" long, so I have ripped off a piece roughly 10"-15 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.

Repeat Taping on Right Side

Masking Window Before Painting
Lee Wallender

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

Quick Tip: Check out this video about how to tape a room before painting. It's a good supplement to this guide.

Fill in Middle Sections With Masking Tape

Complete Masking of Window Before Trim Painting
Lee Wallender

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

Quick Tip: This method of breaking up your tapping into smaller sections, as shown here, gives you better control of the tape than if you used single long strips.

Mask Off Wall Around Window Trim

Mask Outer End of Interior Trim
Lee Wallender

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

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

View of Your Masked Window Trim

Painter's Tape on Interior Trim Before Painting
Painter's Tape on Interior Trim Before Painting. Lee Wallender

A view of your interior trim as it looks after painter's tape has been applied. Now you're ready to begin painting.

Quick Tip: There are innumerable ways to mask and paint interior trim. While this is my preferred procedure, nothing set in stone. Feel free to improvise.

Optional - Fill in Holes and Prime Window Trim

Priming Outside Corner of Interior Trim
Lee Wallender

You might have holes in the wood that need filling. Apply wood filler to the holes, let dry, and then sand flat. Do not over-sand.

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

Begin By Painting Inside Sections of Window Trim

Begin to Paint Inner Part of Interior Trimi
Lee Wallender

Now it's time to begin painting. Should you start on the outside or inside?

I prefer to begin on the inside. If I paint the outer, room-facing section of the trim first, there is always the possibility I may brush my hand across it when I move to the inside part.

Paint the Parts of Trim That Face Room

Paint Outside Trim
Lee Wallender

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, though).

Quick Tip: 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 (see next step).

Remove Painter's Tape From Window Trim

Remove Painter's Tape
Lee Wallender

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 the paint, then you'll need to perform "surgery" with an X-Acto or sharp utility knife.

Toss the trash, recycling what you can, then sit back with some libations and enjoy your shiny new trim!