Dress up plain windows or hide unsightly shade or curtain hardware with an upholstered cornice box.  

Step 1

Measure and Mark Frame

Measure the interior width of the window and add four inches to the overall measurement. Then mark two pieces of 1x8 to the measured length. 

Step 2

Cut Frame

Using a square, draw a straight line on the marks you made on the 1x8s. Cut the wood using a circular saw.

Step 3

Glue Front and Top

Run a bead of glue down one edge of the 1x8. Hold the second piece perdendicular to the bead of glue then screw the two pieces together.

Step 4

Measure and Cut End Cap

Hold up a piece of scrap 1x8 at each end of the frame and mark it at the point where it is flush with the frame. Draw a line over the mark using a pencil and square. Cut along the line using a circular saw.  

Step 5

Secure End Cap and Repeat

Glue the interior edge on the end of the cornice box. Screw the end cap into place using 1-5/8” wood screws.

Repeat for the opposite end of the cornice box.

Step 6

Wrap With Batting

Coat the wood frame with fabric spray adhesive. Wrap the entire box with 1/2” batting. Flatten it smooth to ensure that the batting is adhered to the wood and that there are no wrinkles.

Pro Tip

For a “fluffier” cornice, use thicker batting.

Step 7

Secure Batting and Remove Excess

Staple one side of the batting on the interior corner using a staple gun and 5/8” staples. Leave approximately six inches of excess batting on the other side and cut off the excess. Pull tightly ensuring that there are no wrinkles on the face of the cornice then staple on the interior edge of the cornice box.

Finish the edges by folding the batting with a straight vertical seam in the corners. Wrap and staple tightly on the inside of the cornice.

Step 8

Wrap Fabric

Spray the batting with adhesive. Wrap and staple one side of the fabric on the interior corner of the cornice.

Wrap the other side, and pull tightly to ensure that the fabric is straight and has no wrinkles on the front side.  Staple securely along the same interior edge.  Allow the excess to wrap over the back edge.

Step 9

Secure and Finish Fabric

Staple excess fabric along the back edge of the cornice.  This edge will be against the wall, so it will not be visible. Cut off the excess fabric.

Finish the fabric on the corners by folding it into a hospital corner.  Wrap and staple on the interior of the cornice

Step 10

Attach First L Bracket

Determine the exact placement of the cornice on the window. Level and mark the holes to install a heavy-duty L bracket on the top right-side of the window frame. Pre-drill holes using a 1/4” drill bit.

Use 2” wood screws to attach the L bracket to the window frame.

Step 11

Attach Second L Bracket

Place a large level on the L bracket you just installed and hold up the other bracket on the opposite side of the window until both are level with each other. Use a pencil to mark for the second bracket's placement. Pre-drill and use 2” screws to adhere the second L bracket.

Step 12

Place and Secure Cornice

Place the cornice on top of the L brackets. Secure the L brackets to the cornice using 1/2” wood screws.