The do it yourself resource for homeowners from home improvement professionals.

How to Case a Window

Casings can dress up a regular drywall window nicely and aren’t very hard to install. Here, our home improvement experts explain how to case a window if you’re interested in doing it yourself. If you’d rather us do it for you, don’t hesitate to contact us and make an appointment.

  1. Measure the width of your new wood casing.
  2. Then, measure the width of your existing window stool.
  3. If your existing stool doesn’t extend past the drywall in the same measurement as the new casing plus 1/2″ (on either side), you’ll want to remove it.
  4. Use your utility knife to cut through the caulking and then use your pry bar and hammer to remove the stool and apron.
  5. After that, cut your new stool to the appropriate length (so that it extends 1/2″ past the casing width).
  6. Center the new stool along the opening and mark the edges of the drywall return.
  7. Then, measure from the window to the wall and transfer the measurement to the inner side of the stool and cut notches to fit.
  8. Slide the new window stool onto the window and use your hammer and nails to nail it into place.
  9. After that, mark 1/8″ past the width of the casing on each side and use that measurement to cut your top piece of casing. (Be sure to cut the edges on a 45-degree angle.)
  10. Align the top casing 1/8″ above the opening and nail it into place.
  11. Next, measure from the window stool to the top of the casing to determine the length of the side casings.
  12. Cut one side of the side casings on a 45-degree angle and the other side square.
  13. Align and attach your side casings using your nails and leaving 1/8″ reveal between the inside edges and the drywall.
  14. After that, cut your apron to the same length as your top casing using 22-degree cutting angles.
  15. Center your apron below the stool with the long edge facing up and attach it to the walls with your hammer and nails.
  16. Set the nails below the surface, then use painter’s putty to fill in the gaps.
  17. Next, use your caulk and caulking gun to fill in any gaps between the molding and the wall. Also fill in any corner gaps.
  18. Sand down your filled-in nail holes and then prime and paint your new casing.

Tools & Materials

  • Window Casing Pieces
  • Window Stool
  • Measuring Tape
  • Hammer, Nails
  • Painter's Putty
  • Caulk, Caulking Gun
  • Sandpaper
  • Pry Bar
  • Utility Knife

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