Sewing a Flat-Felled Seam

A flat-felled seam has a very distinctive profile, viewed end-on. Each of the joined edges is enfolded by the other, creating a design reminiscent of the interlocking arms of a Greek Key or a similar motif.

Flat-felled seams are very strong, being made with at least two parallel rows of stitches that reinforce one another. They also have (as suggested by the name) a flat, smooth profile on both sides when finished, which makes them a good choice any time you want both sides of a joined fabric to show or where a seam that didn't lie flat might rub uncomfortably against skin or catch on jewelry.

Variations on the flat-felled seam appear to have been popular throughout the Middle Ages and Renaissance. Heather Rose Jones describes several seen in surviving medieval garments of both wool and linen in her article, Archaeological Sewing. Here I'll be demonstrating what I consider to be the basic flat-felling technique, yielding the type of flat-felled seam most commonly sewn today.


In these instructions, I'm going to label one side of my fabrics "A" and the other "B". Either could serve as the face of the finished seam, depending on the look you want. (Or, of course, if you're making something like a tent or a flag, where both sides will show, both could.)

Before you cut your fabric, decide how wide you want the finished seam to be. Make that your seam allowance. In my sample piece, the seam allowance was about a quarter inch. It is possible (and often desirable) to make finer flat-felled seams. An accomplished needleworker (which description I do not apply to myself) can, given the right fabric and needle, make one that's almost invisible. But it's also fine to make a wider one, if that suits your needs.

When you're ready to sew, lay your fabrics one on top of the other, sides "A" together, with the edges you mean to seam offset by one seam allowance. Join the fabrics one seam allowance from the edge of the upper piece, using the stitch of your choice. Remember that this stitching will be visible on Side B (and only Side B) of the finished seam, against a background of the lower fabric, and choose your thread and stitch accordingly.

I used a basic running stitch for this phase of my seam. A backstitch or a double running stitch would also have worked well.

Now fold the lower fabric up along the edge of the upper fabric. It's edge should meet the line of stitching.

You can press this fold if you like. I was hand sewing and using a linen that creases easily, so I just pinched along the fold.

Flip the upper fabric down, so that the two pieces overlap only along the seam.

Sides "A" of both pieces of fabric will now be facing up. No stitches will be visible on that side of the piece.

Turn the piece over, so that Side B is facing up. You will see a line of stitching and a flap of folded fabric.

Side A

(Sorry about the fuzzy picture.)

Side B

The final step is to complete the seam by securing the fold. Again, you can use whatever stitch you like. In this case, both sides of the stitching will show, one on Side A, against a background of what was the upper fabric, and one on Side B, against a background of what was the lower fabric.

Side B

Side A

Here, I've used the basic running stitch again.

Stitch through all four layers of fabric, close to the fold.

Side B

Side A

Here, I've used a blind hem stitch.

Go through all three layers when taking your "bite" of the fold.

Obviously, in this case much less of the stitching shows on Side A. If you match your thread to your fabric, you can make the seam essentially invisible on that side.


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