| Sewing Patterns for the Modern Woman - Blog Post: Jamie Jeans Sewalong Pt 8: Sew Fly Zip

Jamie Jeans Sewalong Pt 8: Sew Fly Zip

By Allie

Allie is the co-founder of Indiesew and creator of all things pretty on the site. Follow Allie and receive other Indiesew updates by subscribing to the blog.

The Jamie Jeans Sewalong Part 8: Sew Fly Zip |
Today is the day, friends. Today we sew the Jamie Jean's fly zip. If you've been following along with the Jamie Jeans sewalong, you might agree that the steps in this sewing pattern have been pretty straightforward. You might even say that while there's a lot of sewing, pressing, and topstitching, everything we’ve completed so far has been pretty easy.
The fly zip is likely the one technique of the Jamie Jeans sewing pattern that puts it into advanced pattern sewing territory. But that’s not to say that sewing a fly zip is super difficult. I'm guessing a fly zip baffles many sewists because it’s a technique they’ve never done before. But once you sew one or two fly zips, it’ll make perfect sense, and dare I say, you might even consider it easy?
So as I lead you through this part of the sewalong, I encourage you to take your time. Set aside a few hours for this technique. Don’t try to finish your fly zip right before you have to rush out the door. Also, have a pair of ready-to-wear jeans on hand for reference. Some of these steps might seem odd until you see it on your own clothing.
IMPORTANT: When I say "right" or "left" during the fly zip process, I’ll be referring to the right or left side of the pants when they’re on your body. Don’t forget to remark the right and left leg if those markings have worn off.


Shorten Zipper

On day one of this sewalong, I mentioned that using a jeans zipper longer than 4” would work just fine. That’s because shortening zippers (of any kind!) is pretty straightforward.  If you’re using a 4” zipper, you can skip to the next section.
First, set your stitch to a short and wide zig zag stitch. This is a bar tack.
Bar tack stitch settings |
Measure 4” from the top zipper stops and mark with a pin. At the pin, sew a hefty bar tack (or around 10 back and forth movements). Make sure your stitch is wide enough to clear the zipper on either side before you put that pedal to the metal. Breaking a needle during this step is never fun.
Bar tack the zipper |
Using your thread snips or a pair of small scissors, trim your zipper two teeth below your bar tack. You’ll need to gently maneuver your scissors between the teeth.
Trip the zipper to the correct length |


Attach Zipper

Okay, now we’re ready to sew this zipper into our jeans fly. Press the raw edges of each side of the fly towards the wrong side of the fabric. The left side of the pants should be pressed right on the notch. The right side of the pants should be pressed so that the raw edges of the fabric align with the notch.
Press down the raw edges of the zipper |
Pin the zipper to the right side of the fly, so that the folded edge is 1/8” from the zipper teeth.
Pin the zipper to the right side of the fly |
Using your zipper foot, sew the zipper to the right side. I start with the zipper pull halfway down and after about 1/2”, I stop, lift my presser foot and pull the zipper pull to the top. Then, when I begin sewing again the zipper pull is out of the way of my presser foot.
Sew the right side of the zipper using the zipper foot |
Now, bring the folded edge of the left side so that it matches up with the notch on the right. Place a few pins down the length of the folded edge and through the fabric underneath to keep it in place. Turn your jeans inside out and pin the left side of the zipper to the left raw edge of the fly only. Be sure not to pin through two layers of denim.
Pin the zipper to the left side of the fly |
Switch your zipper foot to the opposite side and sew the zipper to the raw edge of the left side.
Sew the left side of the zipper |
Your sewn zipper should look like this:
Sewn left side of the zipper |


Attach Fly Shield

Press the fly shield in half, matching the long edges of the pattern piece right sides together. Serge the bottom diagonal edge.
Press and serge your fly shield |
Turn the fly shield right side out and press well. Serge the long edge of the fly shield.
Turn the fly shield and serge the long edge |
Pin the fly shield to the right edge of the zipper and fly that is already sewn together. Make sure you’re not also pinning through the front of the jeans.  Sew the fly shield to the right fly with a 1/4” seam allowance.
Pin and sew the fly shield to the right side |
Now, pin the fly shield away from the left side of the fly. Turn your jeans right side out. You should still have pins keeping left side of the fly tacked down to the right. Feel for the end of the zipper and place a pin marking its location. With your tailor's chalk, mark a line starting at the top of the fly 1 1/4” from the left folded edge. Curve the line in towards the left folded edge where the bottom of the zipper lies.
pin the fly shield and mark the topstitching |
Topstitch along the curved line you just marked. You have the option to use your topstitching thread or use all-purpose here. Personally, I don’t like the look of a contrast topstitched fly with the center seams of the Jamie Jeans. To me, it sort of throws off the balanced look of these pants. Hence, I topstitch the fly with my blue thread I use for the rest of the seams to make this seam more invisible. Take a look at the Jamie Jeans creations to find what suits your taste. 
Once your fly is topstitched, we need to place a bar tack along that seam to keep the fly shield tacked down. Remove the pin keeping your bar tack to the right, and lay it towards the left and pin. Place a pin along your topstitched line on the curve, where it will overlap the fly shield.
pin the fly shield and mark the bar tack |
For this bar tack, I use a narrow and short zig zag stitch. Here are my machine settings:
Bar tack stitch settings on sewing machine |
Stitch the bar tack along the curved seam for about 1/8” to 1/4”.
Congratulations! You now have a nearly functional fly zip! You may have a small gap at the bottom of the zip and the crotch seam. We’ll close that up now.


Topstitch Crotch Seam

Make sure your crotch seam is pressed well towards the left. Place pins along the seam to keep it flat while you sew. Starting at the back yokes, topstitch down the back of the jeans and between both pant legs.
Pin crotch seam and stitch |
Once you reach the bottom of your zipper, stop sewing, pivot to the left, sew two or three more stitches and pivot back towards the back of the pants. Continue to sew the second topstitching line 1/4” from the first.
Turn around at the zipper |
Your finished fly zip and topstitching should look like this:
Finished fly zip and topstitching |
See that wasn’t so bad, right? Pull on your Jamie Jeans and see how well that fly zip works! I’d love to see your fly zips and answer any questions you have. Tag your social media posts with #jamiejeanssewalong on Instagram, Facebook, and Twitter.

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