Casing a window? No problem we have you covered

Your regular drywall window might be looking too dull, and you are probably asking yourself how to remedy the situation. Well, what you need is a casing that dresses up your window nicely. The good news is that installing a window casing is not hard, and you can do it by yourself. Below is a step by step instructional on how to case a window.

how to case a window


  • Painter’s putty
  • Hammer, nails
  • Sandpaper
  • Utility knife
  • Pry bar
  • Caulk
  • Caulking gun
  • Pry bar
  • Measuring tape
  • Window casing pieces
  • Window stool

Step 1: Take measurements

Start by measuring your new wood casing width. Move on to measure the width of the existing window stool. As a rule of thumb, if the current stool doesn’t give you an extension of ½-inches on either side of the new casing, then you have to remove it.

Step 2: Remove the existing stool and apron

Take your utility knife and cut through the caulking. You can then use your hammer and pry bar to remove the apron and stool. Doing this allows you to design a new window stool that suits whatever design you want.

Step 3: Cut the new stool

Cut your new stool while ensuring that it meets the criteria highlighted in step 1. The aim is to have an extension of ½-inches past the casing width. Since you have all the measurements taken, this step should be rather easy.

Step 4: Install the new window stool

Start by centering the new window stool along the opening. Mark all the edges of your drywall return to help you with measurements. Now, measure the length from the window to the wall before transferring these measurements to your stool’s inner side. Ensure that all the notches are cut diligently and fir perfectly.

Complete the step by sliding the news stool onto your window. Use the hammer and nails to fix it in position.

Step 5: Install the top piece

Mark 1/8-inches past the casing width on each side. You then need to use the measurement to help you cut the top piece of the casing. Note that the edges need to be cut at 45-degree angles. When nailing the top part in place, ensure that you align it at 1/8-inches above your opening.

Step 6: Install the side pieces

Measure the length from the top casing to the stool. Use these results to determine the length of both the side casings. Understand that one side of the side pieces has to be cut square while the other at a 45-degree angle.

Proceed to attach the side casings while leaving a 1/8-inch reveal between the drywall and inside edges. Use your nails and hammer during this step.

Step 6: Install the apron

Measure the length of your top casing and use it to cut your apron at 22-degree angles. The apron has to be centered below the stool and attached to the wall using a hammer and nails. Remember that the long edge of the apron needs to be facing upwards.

Step 7: Finishing touches

You will notice a few gaps left once the installation is finished. Use the painter’s putty to fill all the gaps carefully. The caulking gun should help you fix all gaps between the wall and molding. Don’t also forget to fill any gaps along the corners. Finally, sand down, prime, and paint the new casing.


Casing a window is a pretty straightforward procedure when you follow the above instructional. Be careful with the measurements since they determine how the new casing shapes up.

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