Building a Window Cornice Box

A cornice box adds style to your windows and can help make a room feel taller.


Customize your cornice to match your decor by adding molding or cutting a decorative edge into the box.

Customize your cornice to match your decor by adding molding or cutting a decorative edge into the box.

Materials and Tools:

air compressor and hoses
circular saw
finish nailer
jig saw
measuring tape
screw gun
table saw
2 sheets 1/2-inch medium-density fiberboard (MDF)
4 pieces of 1x3x8 clear pine for ledger


1. Draw a box the length and height of your cornice on a piece of the MDF. If you want a decorative edge on your cornice (such as a scalloped border), draw the design you want within these lines. For a symmetrical pattern, draw a section of your design on cardboard and cut it out to make a template. Trace the pattern multiple times onto the MDF.

2. The length of the returns (sides) on the cornice boards depends on the width of the drapes. Wider drapes need more room. Keep in mind the thickness of the drapes when they are open, since the bunched drapes may take up more room. Make the sides a bit larger than the thickness of the drapes.

3. Use a circular saw or table saw to cut out the box. Use a jigsaw to cut the design. Fasten the box together with a finish nailer.



4. Trim the cornice box with molding.

5. Screw a 1x3 ledger to the wall to attach the cornice. If it is a load-bearing wall, you should be able to screw the ledger into a header. If not, find the studs and attach to the studs.

6. Hang the cornice by screwing it to the studs.

7. Prime and paint the cornice as desired.

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