How to Sew an Overlapping Seam

This is a great beginner seam. It's most often used in sailmaking where you want a very flat profile for your sail. It's also a great seam for big projects because a more complicated seam can be difficult and tricky to sew on large fabric assemblies. With the overlapping seam, the seam only has two layers that overlap, unlike other seams that have three or four layers of folded or overlapped fabric at the seam. In addition to sails, this is also a popular seam used on canopies, awnings and large covers.

We strongly recommend cutting your fabric with a hotknife due to the fact that the fabric edge will be seen when you overlap the layers. One raw edge will be exposed on the outside of your project, so using a hotknife will result in a nice-looking fabric edge and will prevent unraveling.

Here's how to construct and sew the overlapping seam: Mark your desired seam allowance line from the edge of one of your fabric panels on the right or top side of the fabric. We used a 1/2-inch seam allowance in our tutorial video. Apply basting tape to the inside of the marked seam allowance line. Then, take your other fabric panel, with the right side facing up, and overlay it on top of the panel with basting tape, making sure to align the edge of the second fabric with the seam allowance line. Sew the first row of stitches 1/8 inch from the raw edge of the top panel. Reverse at the beginning and end to lock your stitches. Next, flip the fabric assembly over to the wrong side. Sew the second row of stitches 1/8 inch from the raw edge of the other panel, reversing at the beginning and end.

With an overlapping seam, the needle holes go straight through the fabric from top to bottom without the fabric being folded, making this seam construction less water resistant than other seams. A benefit of the overlapping seam is that it's the most economical seam for fabric usage. What this means is that the only fabric "waste" is the width of your seam allowance. Unlike other seams, fabric is not sewn and folded over and sewn again. If you're sewing a 1/2-inch seam, only 1/2 inch of fabric is overlapped and taken away from your usable amount of fabric. So if you have a limited amount of fabric and you need to calculate carefully for fabric lost during seam construction, this is a great seam to consider to save fabric yardage.

Here's a quick breakdown of the pros and cons of the overlapping seam.

Overlapping Seam Qualities

Watch our video below to see how easy it is to sew the overlapping seam. This is a great seam to have in your sewing repertoire. We hope you enjoy this quick seam construction tutorial.