Friday, April 6, 2012

Bay Window Cornice Box Tutorial

I am really excited to share the tutorial for my easy and inexpensive bay window cornice box. While I know that there are a bunch of pelmet/cornice tutorials floating around in bloggy land. I searched high and low for a DIY for a bay window, and couldn't find one, so here it is.
This is the step-by-step for a bay window cornice box.


The sizes and amounts of supplies you need will vary depending on the size of the window you are dressing as well as the height of the Box. I will tell you the supplies I needed for my dimensions.

Foam Board: 4'x8'x1/2"- The foam core I bought is meant to be used as insulation for a home, the sheet was huge, and it barely fit in my giganto mini-van, so beware of this when purchasing. You might need to find a smaller sheet, or sweet talk them into cutting it for you if you have a smaller vehicle.
Staple Gun & 3/8' staples: mine are about 30 years old (if not more), so if you have a staple gun and staples that you love then use those. just make sure your staples are not longer than the thickness of your foam, my foam was 1/2' thick, and the staples were 3/8' so it worked perfectly.
Duct Tape: I just used the cheapest duct tape we had in the house. The fancy stuff wasn't necessary for this project.
Power Drill: I used mine for hanging the cornice. If you don't have a power drill and don't think you need one, just use a screwdriver and some good old fashioned muscle!
Corner Braces: (6) you will need 4- 3" braces, and 2 of the  2" or 2.5" braces. They were the least expensive at walmart.
Hinges: (4)I also found the best price for these was in the hardware section of walmart. You will need 4 - 3 or 3 1/2" Hinges. They come in a pack of 2, so buy 2 packs.
Square Mounting Tabs: These are small pieces of foam that are sticky on both sides. I found them at the dollar store.
Ladder Hooks: (2) these are used to hold a ladder up on the wall usually, but they worked wonders for hanging a gigantic cornice box also.
Soda Can Tabs: (4) I had no problem collecting these because I have a not-at-all secret love affair with Cherry Coke Zero. If you don't have a soda problem like me I'm sure you could ask a friend or neighbor to save 4 cans for you, or just pick a few up next time you're out.
Fabric: I needed 3 1/2 yards for my cornice box, the amount you will need depends on how wide your window is and how high you will be making the box. The way I measured is the very first step, so scroll down and have a look!
Batting/ Insulation: I used thermolam. You will need the same amount of batting as you did fabric.

OK! So Let's get this Bay-Window-Cornice-Box Party started!!!

The first thing you want to do is take your measurements. I drew myself a little diagram so it would be easy to understand when I came back to reference it. I wanted it to be 17" high. I held my ruler about 5" away from the window to take the width measurements, because that's how far I wanted it to come out.

When you have your diagram drawn up it's time to cut your foam pieces. For my window I needed:
1 Piece- 45"x17"
2 Pieces- 31"x17"
2 Pieces 5"x17"
I used a big metal ruler and an exacto knife to cut the pieces, but I'm sure you could improvise and use any straight edge you have around the house.
I cut the front with the straight edge, then flipped it over and went over it by hand on the back.

When you have all your pieces cut you'll want to attach your side pieces to the two end panels. You will need the two smaller hinges, and the foam mounting squares.

Hold the hinge up near the middle of the board and mark where the holes will go. Cover each mark with a foam mounting square (this helps prevent the hinge screws from going through the other side of the foam.)

Attach your hinges on top of the mounting squares. You'll want to screw the screws in at a slight angle.

When both of your small side pieces are attached to the end panels, you will want to measure and cut your fabric and batting. Lay your panels on top of the fabric, and cut the fabric with 3 to 4 inches around the edge. If your fabric has a pattern make sure the pattern is going the same way on all three pieces! 
Make sure you include the side pieces when measuring your cuts, you need enough to wrap around them with a few inches to tack the fabric down.

Once all of your fabric and batting is cut it is time to attach it to the foam. I stapled mine, then went over it with duct tape to make sure it would stay put, you could also try a hot glue gun.
First staple the batting on. Make sure you pull it tight. Cut the corners off of the batting to eliminate bulk.

Next, you want to staple your fabric onto the foam. You will do this the same way you did the foam, but 
DO NOT cut the corners off. You don't want any frayed edges to show on the front of your finished box.
You can also see how I went over the staples with duct tape after I was done stapling.

We're almost there! 

When your three (or more) sections are all finished it's time to attach them to one another. If your window is very large I would recommend doing this in the room where you will be hanging the cornice box.
Attach two hinges to each joint, following the directions on the package. They should look similar to this.

All that's left is hanging it on the window! WOO-HOO! 
This is the part that took me the longest to figure out, but when I finally did it went up really easily. 

Hang your two ladder hooks spaced evenly above the middle window, and two corner braces on the outside edges of the window. I circled them in white so they are easier to see. 

To get the soda tabs ready you need to use a pliers and bend the make the larger opening large enough to fit on your ladder hook. Then bend it in half so it looks like this.


To figure out the spacing for my soda tab hooks I taped markers to my ladder hooks, and held a piece of tape up to it to get the exact spacing. I centered the tape on my middle panel and used it as a guide to attach the soda tabs.

I used a lot of glue, so I let it dry for about 3 hours just to be safe, but once you are confident that it is cured you are ready to hang your cornice box. 
I don't have any photos of this step because I hung it myself, but it's really simple, you slide the soda tabs onto the ladder hooks, and screw the corner braces into the side panels.
Then... you are done! 
Take a step back, look at your hard work, and give yourself a pat on the back!

Linking Up With:


  1. Thank you for sharing your tutorial. Your cornices turned out GREAT! I found you through Addict 2 Decorating's Addicts (no so) Anonymous party. I love your cute blog and can't wait to see more of your creative ideas!

    1. Thanks! I am really happy with how it turned out. So glad you found us!

  2. That is so pretty!
    Excellent job and a great addition to the room! I am so glad you came by to link up to the party at Embracing Change!
    Please come back this week again! I would love to have you there!
    Stacey of Embracing Change

  3. You are so right...I've searched and searched and have found nothing on bay window cornices. You rock for not only coming up with the idea, BUT also putting the plan together, supplies, etc, (which is where I was totally lost!) Thanks a bunch!

  4. Such a great post regarding on no sew window cornice, so it could be better to keep on posting!


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