Introduction: Add a Casing to Dress Up a Window

One of the first things we did when we moved into our new-to-us house was to replace the crappy original single pane, aluminum framed windows from the 1970s.

The new windows are a great improvement, but they still looked a bit plain.

I decided to add some casing around the window to dress it up a bit.

It's a pretty simple project and I think I was able to achieve a nice result even with my minimal skills.

Above you can see the before and after pictures.

Step 1: Step 1: Materials and Tools

The materials list is pretty simple but will depend on the size of your window.

I used 3 types of wood trim.

  • 1. A wide flat board for the sides and top
  • 2. Some narrow crown material for the top
  • 3. at thin trim strip for the top

Don't feel limited to these materials. Use whatever combination you think will look good.

Other materials:

  • Wood glue
  • caulk
  • paint


  • A miter saw is great if you have it, otherwise you can use a hand saw with a miter box(there are only 4 angled cuts required)
  • Nail gun or hammer

Step 2: Step 2: Cut Pieces

It may be easiest to refer to the picture above when cutting the trim pieces.

First cut the 2 vertical pieces from the wide board. They will be the height of the window opening.(Picture A)

Second, cut the top piece from the same board. This will be the length of the window, plus the extra width of the two boards you just cut. See picture B for details.

Next cut the little flat strip a little bit longer than the last piece you just cut. (Picture C)

Lastly, cut the crown(D). The foot will be the same length as piece B, but longer on top. The crown will be cut at 45 degrees. You'll need to cut 2 small pieces of crown to run from the crown to the wall(E)

Step 3: Step 3: Assembling the Pieces and Putting It All Together

Next, glue and nail the header piece, as shown.

Refer to the pictures, but basically you have the thin strip piece, then the wide flat board, and then the crown.

I used a nail gun and glue to hold it all together.

After everything has dried, nail the two vertical pieces on either side of the window and then sit the header on top and nail it in place. A little caulk and paint to fill in any gaps and you are almost done!

The last thing I did was to extend the sill. It was too short and looked silly. I cut a piece of wood for each side and glued them in. I then sanded and filled until it matched the existing sill.

That's pretty much it! I think the end result really makes the windows look nicer, and the cost is minimal. If you enjoyed this, please check out my other instructables.