Inserting a Lapped Zipper
If your skirt's zipper is on the side or in front, you will need to insert a lapped zipper rather than a centered one. The idea is that rather than having the two folds of fabric meet on top of the zipper teeth, there is one flap of fabric that laps over the zipper teeth and just a little of the fabric on the other side of the zipper.
Sewing the Zipper to the Seam Allowance
Begin by basting the seam closed like you did for a centered zipper. Press the seam open. Fold the garment pieces away from the seam allowance that will not be the side of the exterior overlap. This should be the seam allowance belonging to the back piece if the zipper is on the side. If the zipper is in the back or in the front, you need the seam allowance that belongs to the right side piece.
Line the top edge of the zipper tape up with the upper edge of the seam allowance. The zipper should be face down, and the outside edge of the teeth should be right along the seam. In other words, one side of the zipper tape and all of the actual zipper hardware should be lying on the seam allowance. Stitch along the tape close to the teeth, as shown in FIGURE 18-1.
Lapped zipper, step 1: Sew the zipper tape to one seam allowance.
Lapped zipper, step 2: Sew along the fold between the seam and the zipper teeth.
Making the Lower Lap
Fold the zipper out and the seam allowance under. Adjust the fold of the seam allowance so it is close to the teeth but not over them. Stitch along the fold of the seam allowance between the seam itself and the zipper teeth, as shown in FIGURE 18-2. You are still only sewing through the zipper tape and the one seam allowance.
Making the Upper Lap
Now open out the garment, laying the zipper flat. This is similar to pinning down a centered zipper, except it is already anchored on one side and you can see that it isn't actually centered. Sew across the bottom just below the metal stop and up the previously unstitched side close to the teeth, as shown in FIGURE 18-3. Take out the basting stitches.
Lapped zipper, step 3: Sew the zipper to the skirt, forming the upper lap.
There is a quicker way to put in a lapped zipper, but it will probably not turn out quite as neat. If you are making something very casual, or you are practicing on cotton before tackling that synthetic suede, you might want to try this shortcut.
Stitch the bottom of the skirt seam, but don't baste the zipper area closed. Turn the left or front seam allowance under ⅝″ and the right or back under ½″ folded allowance along the edge of the teeth. Stitch close to the teeth. Lay the ⅝″ fold over the zipper, simulating the closed seam. Sew this side of the fabric to the zipper, down the side, and across the bottom. You may need to sew from the outside instead of the underside in order to be sure the lap stays straight.
If you want to avoid zippers as much as possible, consider making a wrap skirt. Cut a skirt back and two skirt fronts, which you sew to either side of the back. Add ties to either side of a long, narrow waistband, and hem the sides and bottom.