my favourite fly zip insertion method

Fly zips can be very tricky to insert and can end up really messy.

There are so many different methods available, but I find this method gives me good results. It really is just a matter of steps and doing each in the correct order.

I practiced this method a couple of times before I went anywhere near my good fabric. If I’ve not sewn pants for a while, I will whizz up a sample with a piece of leftover fabric.

It really is personal preference as to what side the fly zip opening sits. The below is sewn with the opening on the right.

Mark the centre front line on both pieces, with chalk or a washable marking pen. I have added an extra 1cm seam allowance on the right side of the front pant and curved it off at the end to make it easier to finish the seam. Sometimes this is a squared angle and hard to finish nicely. Apply interfacing to the fly facing and the fly extension, on the underside.
Some home sewing patterns use a grown on fly facing, again this is personal preference and not really used in RTW.
Fold the fly extension in half and I bag out the lower edge. Have a look at a ready to wear pant if available. It’s always nice to investigate how garments are finished and we all want a professional looking garment. Binding can be used on the fly extension edge as well (mine above is overlocked) These seam finishes can be added once your confidence grows.
Place the right sides together and sew the crotch seams together, stopping at the marked notch, reverse stitching to secure.
Fold down the right side pant to the notch.
Sew the facing to the left front, aligning the centre front edges and carefully stop at the notch. Reverse stitching to secure. The centre front facing seam can be cut back by half if fabric is thick, to reduce the bulk.
Turn over and lay flat. Press seam towards facing and edge stitch close to seam.
Place the closed zip, right side down on the fly facing, lining up the zip tape with the centre front seam. Make sure the stopper is clear of where the decorative fly topstitching is sewn.
I usually place the stopper about 7mm higher than the notch point, the point where the crotch seam is stitched to. This will give you enough clearance to topstitch , without hitting the stopper with your needle and stuffing your sewing machine!
Change to your zipper foot and baste with a large stitch, I use 6. This will be removed shortly.
Stitch down with two rows on the other side of the zip tape (normal stitch length)
Note: remember to fold up the end of the basted zip tape side – as image above.
This clears the tape out of the way while you do the decorative fly topstitching.
Fold the fly facing back to the underside. Following the facing shape and bast 6mm in from the edge. This will hold the facing in place.
From the correct side, topstitch using a template. Remove basting stsiches.
Press under 0.5cm seam allowance to the underside.
Attach the zip extension to the left side of the zip tape.
Sit the fly extension underneath the pressed seam allowance and topstitch through all layers, as far as the dot.
Sew a bartack at the bottom of the zip, avoiding the stopper and through all layers.