First thing is to decide where you want your zipper. I decided to put mine in the side since this pillow was 48" long. This way you can slide the pillow in from the side making it easier to insert. But the same method can be used for a bottom placement.
Cut your back pieces. I chose to cut the first back piece the same size as the front, because I wasn't sure how much I would need extra for the "lap". I trimmed off the excess once I completed the back pieces. Cut a smaller piece for the under side of the "lap". My flange is 2", and I would need 1/2" seam allowance for both the flange side (the outside edge of the pillow) and the zip side. I wanted that zipper about 1" in from the stitch line of the flange. I made my smaller piece 4" wide 2" flange + 1" seam allowance + 1" from the bottom = 4". Make it wider if you need to depending on your seam allowances and the size of your flange and how far up from the flange you want to place it.
Flip this over and press really well being careful to avoid the zipper teeth. Some zippers will melt. Topstitch down the zipper. Remember to start and stop at the same place. Give it a good pressing.
To attach the other side of the zipper, close the zipper and transfer the marks to the other side.
Measure in 3" on the other piece just like the first piece.
Remove the paper from the wonder tape and lay the right side of the zipper to the large back piece. Line up the raw edges and press down firmly to seal that tape. Stitch in place.
Flip it over and it should look like this.
And if you prefer to measure, it's about 3/4". Be sure to press that fold. If you want to pin it in place, do it now. Because this fabric really pressed well, I didn't need the pins. But pin away if you prefer. Just don't pin it to the other side.
Now unzip the zipper.
And it looks like this. Give it another good pressing.
Line up both pieces right sides together and even up the edges. I had to cut a little off the side with the zipper. You can also do the dog ear adjustment at this time. Here is a great tute on this adjustment. Once they are all neat and tidy, stitch those puppies together. ***Remember to open your zipper so you can turn it right side out.***
I forgot to take pictures of the last step, and that is to close the last part of the zipper. I used to do it another way, but this way is easier. Trust me.
This is a different pillow but the same method. See that hole left in the fabric from the end of the zipper to the end of the pillow? That need to be closed.
And now you know how to install a lapped zipper in a flanged pillow. No more envelope closures for you or me! I hope this helps you!
If I haven't made something clear, please feel free to email me with questions.
Next up is a super easy trick I've learned to get perfectly pressed seams on these pillows without all the fidgeting of rolling the seam and burning your little fingers. Stay tuned. You'll love how easy it is. And you probably already have what you need to make it happen.