Broken zipper? No need to replace your pants. Replace the zipper.
You will need: seam ripper, tweezers, new zipper, zipper foot, button foot, and matching thread.
It's one thing to sew on a zipper for a project you are sewing from start to finish. But it's a different thing entirely to replace a zipper on ready to wear garments. Sometimes they can be a little tricky. No worries. That's not the case with Dickies work pants. The way they are sewn, you don't have to worry about too many pieces. Just before starting any alterations, I like to take pictures of the garment so I can have a reference to refer back to if I need to. Alterations is all about deconstructing a garment and then putting it back together.
I used a razor seam ripper to detach the zipper from the waistband and the fly including the bar tacks. Then I cleaned up all the loose threads. Sewing tweezers are great for getting all the little bits. I unpicked very little of the waistband, just enough to slip the old zipper out. The construction of these pants is just one piece of fabric folded and sewn. Also the zipper edges align with the folded edges of the fabric, which made aligning the new zipper easy.
You can pin the new zipper in place. But I much prefer basting it in place. Pins can make the zipper not lay flat and can also easily poke you as you sew in tight spaces. I placed the new zipper in the same spot the old zipper was. It nicely aligned with the folded edge of the fabric. I started at the bottom, making sure the zipper stop was in the right place. Here is a before picture. You can see about where the zipper stop should be and notice also that the zipper tape is folded in and out of the way.
Sew on Zipper
I used a zipper foot (as in the picture) for sewing on the zipper. I aligned the zipper teeth using the zipper foot. But I sewed on the right side of the zipper foot, as that is how the zipper was originally sewn in place. I did my best to be as neat as possible in this step as this will show on the front of the pants. I was not able to sew from the beginning or the end of the zipper with a zipper foot. But I'll show you how I worked around that later. The new zipper was a little longer than needed, but I just trimmed it down to size. It's very important to remember to pull the zipper pull out of the way before cutting. You don't want to cut that away. As I still had the zipper foot on the machine, I didn't worry about cleaning up the sewing just yet. I moved on to the other side of the zipper.
I closed the pants and aligned them. The edge of the zipper aligned nicely to the edge of the fold in the fabric. I basted the zipper in place. Then unzipped it and sewed it in. Again trimming away the excess bit of zipper and tucking it in under the waistband.
Remember I removed the bar tacks? Bar tacks are important to hold everything in place and reinforce areas that come under stress. This is the time to put them back. As I could not get my regular foot in this area, I used my button foot instead. I set my machine to zigzag with a stitch length of zero and a width of 2.5. I double checked that my needle would not hit the foot. Then I made several stitches to hold the zipper down.
I forgot to take an after picture. But on the back side, I hand stitched closed with the zipper tape tucked it. This held it nicely. On the front side I was then able to stitch the bar tacks on again using a standard foot.
I reattached the waist band and any other stitching needed to neaten things up.
I hope this can help you if you are replacing a zipper on a pair of work pants. Happy sewing and have a lovely day!