How to Case a Window in My Daughter's Room

Installing window casing on a bedroom window adds a decorative and finished touch to the wall. Made from wood or composite, casing covers gaps between the sides of the window opening and the glass, and frames the window. There are different styles of casings, such as traditional styles where the four corners are cut at 45 degrees, and window-sill casings, where the top and sides are cut with the window sill. With accurate measurements and the right tools, you can easily construct and install casings for your daughter’s bedroom window.

Combination square
Measuring tape
Miter saw
Hammer
Finishing nails, 4d
Sandpaper, 120-grit
Wood glue
Finishing nails, 6d
Wood putty
Touch-up paint supplies

Instructions

- 1
  Set the combination square on a top corner of the window, against the window jamb, ensuring it protrudes by 3/16 of an inch, and mark the edges of the reveals with a pencil. Also, mark the reveals at the other top corner, the side jambs and the upper jamb’s midpoint. A reveal is the tiny gap between the casing and the window jamb that provides room to adjust the casing if the lengths do not fall flush.
- 2
  Extend a measuring tape between both the upper corners of the frame, and add to the measurement twice the reveal before recording it.
- 3
  Cut the head or top casing to the noted measurement using a miter saw, with its sides cut at 45 degrees. Also cut 45-degree miters on an end of each side casing to match the miter cuts on the top casing.
- 4
  Drive 4d finishing nails over the pencil marks in your jamb to secure the top casing to it. Flip the casing for the left upside down over the top casing, with its mitered edge at the base of the window opening. Mark a line over the end of the side casing that's flush with the top casing. Cut along the line using a miter saw.
- 5
  Dry-fit the side casing next to the top casing to ensure it forms a tight fit. If there is a slight gap on the mitered edges, simply sand the wood surface using 120-grit sandpaper until smooth.
- 6
  Spread wood glue over the mitered edges of the side and head casing. Join the two ends together, and wipe away excess glue from the reveal.
- 7
  Hammer 6d finishing nails through the side casing to secure it in place, no further than 1 inch from the outer edge. Also, hammer nails through its inner edge, no further than 1 inch from the inner edge. Begin nailing the casing at the top, and work your way downward, alternating between the inner and outer edge. Drive a row of five nails through the inner and outer edge of the side casing.
- 8
  Repeat the process for the casing on the other side. Hammer a finishing nail through the top casing into each side casing.
- 9
  Cover the nails with tinted wood putty and leave it to dry. Sand the dry putty lightly before touching it up with paint.

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