December 6, 2019  

How To Trim A Window (Our New Modern Craftsman Trim!)

Modern trim is an easy way to add style to your builder-grade windows. Learn how to trim a window yourself with this simple Crafstman trim tutorial!


A huge thanks to Wagner for sponsoring this post. All content and opinions are 100% my own! See my disclosure policy for details. 

Our house is about as cookie-cutter as they come. Although it doesn’t have a lot of style, being able to add upgrades and customize things was a big reason I was sold on buying a builder grade house in the suburbs. I looked past the boring carpet and beige walls and saw a blank slate.

I’m a beginner DIYer, so knocking down walls and moving around plumbing is not in my wheelhouse. But I figured if I had a newer house with a great layout and no major renovation needs, I could put my own touch on this house through some fairly simple DIY projects.


When I gave our powder bathroom a makeover last year, I decided to try my hand at adding trim to the window (all of our windows have plain old drywall around them). I knew the trim would make it feel more special, and wow did it ever make a difference!


So when it came to our front room makeover this fall, adding window trim was a must on my project list. This time I have two large windows, a much larger project than the one small window in our bathroom.

I documented the process this time around so I could share this DIY Craftsman window trim tutorial with you today. And I partnered with my friends at Wagner to speed up the process of painting all of the trim using a paint sprayer!

Before we dive into all of the details for painting and installation, let’s first take a second to enjoy these before and after photos, shall we? This is the large window in our front room. Can you believe what a difference a little trim makes?!





DIY Craftsman Window Trim

Adding or upgrading window trim is a great way to elevate the look of your home. And it’s a beginner-friendly project with no complicated angled cuts!


  • 1×2 MDF Boards*
  • 1×3 MDF Boards*
  • 1×4 MDF Boards*
  • 1×6 MDF Boards*
  • White Semi-Gloss Trim Paint
  • 2-inch Brad Nails
  • Construction Adhesive
  • White Paintable Caulk
  • White Wood Filler
  • Fine Grit Sanding Block (80-grit and 120-grit)
  • 2 ½’’ Wood Screws (I used 3 on the smaller window and 6 on the big window)

*I calculated all of the board lengths based on the workbook in this tutorial from my friend Christene.


  • Wagner Flexio 3000 sprayer
  • Wagner Spray Tent
  • Miter Saw (there are no angled cuts so use any saw that you can get straight cuts with)
  • Jigsaw (or you could use an inexpensive hand saw)
  • Drill
  • Sander
  • Brad Nailer
  • Plastic Drop Cloth
  • Caulk Gun
  • Level
  • Measuring Tape
  • Square
  • Carpenter’s Pencil
  • Clamps
  • Small Paint Brush (a quality 1” trim brush or a small foam brush would work great)

Note: My windows are surrounded with builder-grade drywall, no trim of any kind. If your windows have existing trim, you’ll need to use a crowbar to pry that trim off before you start this project. Use a razor blade or scraper to cut any caulked seals.

Step 1 – Planning

The window trim is made up of the following:

  • Apron x 1×4
  • Sill – 1×6
  • Sides (2) – 1×4
  • Top – 1×3
  • Header – 1×6
  • Crown – 1×2 and 1×3

Your first step is calculating the lengths of boards needed for your window. Rather than try to explain this in paragraph form, I will refer you over to my friend Christene’s blog post on installing Craftsman style window trim.

You can download her workbook which does an awesome job helping you calculate all of the measurements based on the dimensions of your window. I followed the exact measurements she uses!

Note: I did not install casing/trim inside the window box. This saved on material costs and simplifies the installation process. I simply painted the drywall on the inside of the window box with the same trim paint so it all looks cohesive.


Step 2 – Selecting Materials

You have a few options when it comes to trim. You can purchase specialty trim or go with simple pine boards or MDF boards. I chose MDF for a few reasons:

  1. It is smooth without knots, great for painting
  2. It’s the most affordable option
  3. The boards are straight and consistent, fewer irregularities like you’d get in your standard pine
  4. The edges come with a slightly rounded edge

I used the pre-primed MDF from Home Depot which is the same MDF I’ve used for my entryway board and batten wall and the board and batten in my bathroom.

MDF is made up of recycled wood. Manufacturers take scraps of wood from the production of other lumber and turn those scraps into MDF by adding glue, heat, and pressure.

A few reasons you wouldn’t want to use MDF is if you plan to stain your trim or if you’re installing it in an area prone to moisture. If it’s going to be around a sink or in a bathroom, you’ll want to research the proper way to paint and seal the MDF, use moisture-resistant MDF, or opt for another trim material.

There are many different options for trim, but this is the method I landed on as a way to get simple, modern trim without breaking the bank.


Step 3 – Cutting

Cut all of your boards to the proper lengths. I used a miter saw for this. There are no angled cuts in this Craftsman trim design so you could use a different saw if you don’t own a miter saw.

With all of the different board sizes and lengths, I found it helpful to have my cut list on paper so I could check things off as I went.

The only more complex cut you need to make is the cutout notch on the window sill. Christene’s workbook helps you measure this. Use a square and carpenter’s pencil to mark your cut lines. You can make the cut with a jigsaw or simple hand saw. Dry fit it to your window to check that it’s the right size. 

After cutting everything to the proper lengths, use your sander (I used an orbital sander) to sand the cut edges of the boards smooth. Since I purchased the pre-primed MDF, I only needed to sand the short edges I cut. 

Step 4 – Painting Set Up

You could use a paint roller on the boards which is what I did in our powder bathroom, but I really wanted to achieve a more smooth, professional finish this time around. So I used my Wagner Flexio 3000 sprayer to get a smooth coat of paint without any brush strokes. There is a noticeable difference!


Using a paint sprayer requires some setup but it saves so much time in the long run. I painted the trim in my garage before installing using a disposable plastic drop cloth on the floor and a spray tent (like a popup tent) to contain any overspray.

Arrange your trim on the floor, leaving a small space in between each board so you can paint the edges. Use scrap boards underneath to raise the trim off the floor a bit (lay scrap boards perpendicular to your trim). If you have enough sawhorses, you could use those to raise the trim higher instead of using small scrap boards as I did. Just protect your sawhorses with drop cloths!


Step 5 – Painting

I find it helpful to paint all of the trim before installing them. And there’s no better way to paint a lot of boards quickly than with a paint sprayer! That’s where my friends at Wagner come in. I used Wagner’s Flexio 3000 sprayer to stain my deck last summer and I’ve been looking for an excuse to use it again!

The Flexio 3000  is a hand-held sprayer that can be used indoors and outdoors, all you need to do is fill it up with stain/paint and plug it into a standard outlet.

It comes with two different nozzles. The iSpray nozzle is designed for walls and siding (what I used for this window trim project) while the detail finish nozzle is best for smaller projects and thinner materials like stain (what I used for my deck).


When you’re ready to paint, pour your trim paint into the plastic cup and screw it onto the spray gun. Adjust the settings on a couple of dials (Wagner provides a great chart on what settings to use) and you’re ready to start spraying.


To spray, simply pull the trigger. Start spraying off to the side and steadily sweep the sprayer across the boards. Try to maintain a steady distance (about 8 inches) away from the boards. And instead of bending your wrist, focus on keeping your wrist and arm straight and moving your entire body instead. This will give you greater control and result in a nice, even finish. I was basically walking back and forth up and down the boards.

If you use a similar set up to mine, it works best to paint one coat on the sides facing up and facing you. I did two coats (the boards were already pre-primed). Let dry overnight if you can then flip the boards over and repeat the painting on the other two sides of the boards. (Note that you don’t need to paint the backside of the Apron, Sides, and Header since those face the wall.)


Step 6 – Installation

Now it’s time to install your window trim! 

Place a thin zig-zag line of construction adhesive to the back of each board, then use a brad nailer and 2’’ long brad nails to secure your trim to the wall (make sure to use a level!). Since you likely can’t nail every board into a stud, the construction adhesive will ensure the boards are securely attached to the drywall. 

Start with the window sill, then the apron, then work your way up. 

Here’s the order of installation:

  1. Sill
  2. Apron
  3. Sides
  4. Top Pieces (Top, Header, and Crowns stacked together before installing on the wall)

When you get to the top 4 boards the run horizontal along the top of the window, I find it works best to assemble those prior to installing on the wall. With standard 8 feet ceilings, there isn’t enough room to hold the brad nailer above the last 2 boards so it’s best to attach them to the header on the floor. I also drilled a few screws through the two crown pieces and down into the header.


Step 7 – Finishing

Now it’s time to hide all of the nail holes, seams, weird gaps, and imperfections. This step makes all the difference! It’s really amazing to see how much caulk and wood filler can do to create a polished, professional end result.

Use white wood filler to fill in all of the nail holes then sand smooth with a fine-grit sanding block (go over everything with 120-grit first, then back over with 80-grit). I like the block as opposed to sandpaper because it helps me sand the wood filler down flush with the face of the trim board. A plain sheet of sandpaper could sand the filler too deep.

Use white paintable caulk (the paintable part is important!) to fill in all of the seams between boards and the spots where the edges meet the wall. Rus a small bead of caulk along the seam, dip your finger in a glass of water and use your finger to smooth down the caulk. Then use paper towels or a rag to clean up any excess caulk before it dries.

Quick Tip: Hang a wet rag from your belt loop so you can wipe the caulk off of your fingers as you go.

Once the caulk and wood filler are both dry, use a small paintbrush to touch up the paint. Also, use a small paint roller to roll the trim paint on the exposed drywall inside the window box so it matches the surrounding trim.


Isn’t it amazing what a little trim can do to a builder grade room?! I’m so in love with how this turned out and the paint is as smooth and professional as can be thanks to my paint sprayer.


If you’re thinking about adding modern Craftsman window trim to your house, I hope this blog post was helpful! I highly recommend using a paint sprayer to get that smooth, professional look you’re after. You can visit to learn all about the Flexio 3000 paint sprayer I have.

Now that my window trim is done in this room, next up is finishing the baseboards (I removed them when I installed the new laminate floor). I’ll also be replicated this trim style around our interior doors soon!

And if you’re looking for more tips to save time painting, check out how I painted our living room quickly using another one of Wagner’s time-saving products.

Looking for more planning inspiration? Take a look at these blog posts:

Have a fantastic day!

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