Decorate In A Day - DIY Styrofoam Cornice Kits - CALL NOW 623-878-7350

Instructions For Cornice Kit

Step-by-Step Instructions for Cornice Kit

All styles are covered the with the same techniques.

All Styrofoam cornice kits include instructions to assemble the cornice and also how to decorate it. It’s easy as 1- Assemble, 2- Decorate and 3 -Hang. See how to measure for fabric needed.
Assembly Instructions, Materials Needed: Print This Web Page
• Scissors
• Ruler or straight edge
• Fine point felt tip marker
• 4″ break-off utility knife or hack saw
• Tape measure

DO NOT leave even a low heat gun plugged in for an extended time and then use it on the Styrofoam. Hot glue will melt it.

We recommend you test on a small, hidden area prior to applying on your final product.

Step 1 – Assembling the Cornice

  1. Measure Your Window Size

Measure the width of your window including blinds, curtains, or molding (whichever is the widest) and add a minimum of 1? per side, or more, according to personal preference.

  1. Cutting the Extension (if necessary)

Example: 74? window + 1? on each side = 76? cornice

Purchase units for 78? Window (1 window kit and 1 extension kit)

You will need to cut one of the 16? extensions to get the 76? length. You will cut 14? from one 16? extension. To cut, draw a line, using a ruler as a guide, from top to bottom on the back (flat side) of the cornice. A hacksaw, electric carving knife, or retractable utility knife extended about 4? may be used to cut the polystyrene forms. Use a slow up and down sawing motion rather than trying to slice the piece.

Preparing to Cut Cornice Kit to SizeCutting Cornice Kit to Size


>>Helpful Hint: If you have a “rough” or “crooked” cut, simply heat a clothes iron and “tap” it against the rough surface until it is smooth again!! Wrap a piece of aluminum foil around the surface to be smoothed before applying the iron


C. Assemble the Returns

Add Returns to Front of Cornice

Using the LOW TEMP GLUE GUN, apply the glue to the end of the extension and press the endcap to it aligning the contoured surfaces. Apply the glue liberally, following the shape and making several passes across the middle. Glue only one piece at a time.


D. Joining the Polystyrene Sections
Assemble the cornice using the LOW TEMP GLUE GUN. Line up the front contour of the cornice evenly.
>>>Helpful Hint: You may reinforce joints by using “white duct tape”. Tape over the joints. You can simply slice through the tape along the tuck grooves. This is recommended for windows with a southern exposure subject to intense sunlight


Step 2 – Decorating the Cornice

A. Measure and Cut Your Fabric Strips

Decorate Styrofoam Cornice KitYou will be using fabric strips to cover each contour of your window cornice. Determine the fabric width by inserting a tape measure into a fabric groove and bringing it around and inserting it into the next fabric groove and add 1? to 1 1/2? depending on the thickness of the fabric. To determine the length of your fabric strips, measure the front of the cornice, add the length of the two returns then add three inches. This will give you enough length to cover the cornice and fold over a hem at each end of the cornice.
>>>Helpful Hint: For a gathered affect add 3 inches, instead of 1?, to the width and double or triple the length of your fabric strip, depending upon the amount of gathers you want.
If you should run out of fabric or need to start the next piece DON’T PANIC! Simply fold the next strip of fabric over and lay it on top of the first strip. Continue tucking as you have been doing.

Wraping Fabric Around CornersIf your cornice can be seen from the outside or as you walk through an Arcadia door, for example, you will probably want to finish the back with fabric as well. As before, measure the length and width and simply tuck into the grooves on the back.
When tucking the body of the cornice, place the cornice across a table top to provide support. Do not prop it up on the ends of the returns and tuck the fabric. Styrofoam is very strong, but can be broken. If you should accidentally break a section, however, you can simply glue it back together!!

B. Applying Your Fabric Strips

Cover contours 1 and 3 first. Lay the fabric over the top of your cornice. Position the fabric so it can tuck into both the front and back fabric grooves and around the full width of the cornice around the side to each return end. Start at the center and work toward the return edges, tucking fabric into the front tuck groove first. Trim the fabric on the return ends to one inch and fold under to give a finished look where the return meets the wall.

Tucking to back side of CorniceWraping Fabric on Cornice KitApplying Fabric to CorniceTucking into Grove on Back of Cornice Kit




• #1-To create the mitered fabric corner, fold the fabric strip over the top of the cornice and cut along the inside edges of the return to the back of the cornice on both sides.
• #2-Flip the fabric strip to the front and cut along the inside of the front to the inside of the return, creating a “flap” on both ends.
• #3-Tuck the flap for the return into the tuck groove.
• #4-Fold the fabric strip from front to back, creating a mitered corner as you bring it back.
• #5-Tuck fabric strip into back tuck groove.
DECORATING TIP: You can create a dimensional look by adding three or four inches to the width and doubling or tripling the length of the fabric strip. Tuck in a bit at the center and a bit at each end of the return. Complete by gathering and tucking the fabric into a tuck groove. Continue this until one side of the strip is tucked into one of the grooves. Then tuck the opposite side into the other tuck groove. When the whole strip has been tucked in, you can adjust the material until you like the appearance. Several short strips of fabric can be used. If you combine flat and gathered styles, do the flat strips first.
Step 3 – Hanging Your Cornice
IMPORTANT: Different cornices have their mounting groove on the back of the cornice in different places. Make sure you identify where the groove is for your cornice so that your bracket placement will be perfect.
A. Installing the Hardware
To mount each hardware bracket, use the two wall anchors and two screws included. After determining the appropriate placement for the hardware based on the desired height and width of the cornice, mark the wall through the slot where you will place the two anchors and screws. Drill holes, tap in both anchors, screw in the top screw, leaving 1/16? between the head of the screw and the wall/anchor. Set the hardware onto the screw, lower the bracket in place, and then tighten the screw. Insert and tighten the lower screw.
B. Hanging Your Cornice
Push the bracket flange into the back-tuck groove running horizontally along the back of the cornice. If the cornice is not quite centered on the window re-insert the bracket flange in the tuck groove to center the entire cornice on the window.
Styrofoam Cornice products purchased from us are covered by a Limited Warranty. Use of any not recommended adhesive voids all warranties. For further information call Claudia at 623-878-7350