SewLibra:
Start by finishing the fabric edges (serge) and choosing a zipper longer than your opening. Place the zipper pull above the top edge of the fabric and pin or mark where the zipper stop is.
SewLibra:
I am using a 5/8" seam here, but you can make it wider if you wish. I'm also using contrasting thread and zipper so you can see it better. Sew the seam from the bottom to your zipper stop mark and backstitch. Do not baste the remaining opening.
SewLibra:
Looking down on the fabric's wrong side, press a 5/8" seam allowance (SA) on the right side of the opening. If you used a 1" SA, then press a 1" SA. If you are left-handed you can do this on the left side instead.
SewLibra:
On the left side press a 1/2" seam allowance. If you used a 1" seam allowance, press the fold 7/8". The overlap should be 1/8" more than the underlap no matter the width of your SA, but at least 5/8" to accommodate the zipper.
SewLibra:
If you need to stabilze the zipper area, do it now. You can use either one-sided or two-sided fusible tape or interfacing.
SewLibra:
With fabric and zip right side up, position the zip on the 1/2" (narrow) side with the needle at the right side of the foot. Start 1/4" up from the zip stop and backstitch. Continue to sew guiding the zip with your hand. Pins/tape are not needed here.
SewLibra:
Here is a close-up of where to start sewing past the zipper stop. Because the stop is right at the seam opening, it can cause the stitching to show if you start sewing too close to it. The topstiching coming up will anchor the bottom of the zipper.
SewLibra:
Sew closely to the zipper teeth the length of the fabric to the edge. Your tab will not be in the way since it's past the fabric edge so you will get a nice straight line! Remember to backstitch at the beginning and end.
SewLibra:
Pin or mark right below the zipper stop on the 5/8" folded side. Place 1/2" wide tape at the edge for a stitch guide, ending at your pin. I like Sewers Fix It Tape from Nancy's Notions, which is 1/2" wide.
SewLibra:
Align the overlap so it is flat and smooth, and use a piece of tape to close the opening. I like to place it vertically so I won't be sewing through the tape. I made this piece shorter so I wouldn't be confused on which side to sew!
SewLibra:
For the next step you will need to leave long thread tails on both needle and bobbin threads and move the needle to the left side of the zipper foot.
SewLibra:
Drop the needle directly in the seam ditch. Do NOT backstitch. Stitch on the fabric beside the bottom edge of the tape, pivot, and use the tape as a guide all the way down to the fabric edge.
SewLibra:
Here I'm approaching the zipper tab, but since it's beyond the fabric I don't have to stop, lift the zipper foot and unzip, or end up with crooked topstitching.
SewLibra:
If your topstitching is satisfactory, remove your tape. If not, it's not a big deal to unpick the stitches and do it again. As long as you stitched beside and not on the tape, just leave the tape as is.
SewLibra:
Bring the top thread tail to the wrong side with a needle and tie it off on the wrong side with the bobbin thread. This looks so much neater than backstitching. I have no idea what happened to the color in this pic?!
SewLibra:
Here is the outside after topstitching. Of course I would normally use matching thread, but either way I want a straight line!