My customers are always challenging me. One recently asked if I could add a zipper to an existing Oversized Beach Tote so that she could use it as an overnight bag. So in my usual way, I researched, I thank (thunk? thought? perseverated?) - and over-thought it in my anal/perfectionist way....
The existing solutions on the internet require using a fabric flap. I finally decided that sometimes simplicity is the best solution and purchased a separating zipper that was about 4" longer than the bag. I simply basted it to each side of the bag to test the idea.
With the zipper separated, baste one side to the bag. Sew to within a half inch of the side seam.
To sew the other side of the zipper, first attach it to the sewn side. Pin it in place so that it is even with the other side. Then separate the zipper and sew it, stopping within a half inch of the side seam.
I felt that it was a successful solution to the problem presented. The beginning and end of the zipper extend a couple inches past the opening.
I also tried tucking in the ends of each side of the zipper for a cleaner look.
To tuck in the "bottom" of the zipper, I had to invert the zipper before joining it. That part is a little fiddly, but the bag would not have to be completely unzipped if it was tucked in.
Either way, a quick, simple way to add a zipper to a purchased or finished tote!