Have you ever tried to take apart the side seams of a man’s shirt? You may have tried to do that if you wanted to make the shirt smaller; then you will have noticed that you cannot simply loosen this seam as you do for other garments – the seam is stitched a little differently. It is a flat felled seam. With this seam, when you look from the top and bottom you will not be able to see the usual seam allowance projected out. Everything is neat and flat.

In a flat felled seam the seam allowance is sewn flat. And that too on the face of the fabric. This is why you cannot see the seam allowance. 

It is the chosen seam for sports clothes, men;s shirts , jeans inner seams , kid’s clothes. The advantages of this seam is that it is quite a strong seam – what you have is a double stitched seam. This double stitching is attractive too. Then, the seam allowance is hidden quite neatly. So no need for any additional seam edge finish. Less irritating to the skin so best inside a kid’s dress. So all in all, an all-in-one seam. 

It is not made the same way as a regular seam. In a regular seam you keep the fabric piece rightsides together and stitch the seam. Then finish the edges. But in the flat felled seam you will be keeping the fabric pieces wrong sides together and then sew the fabric edges to the inside hidden under the folded seam allowance. Let us see how this seam is stitched.

How to sew the Flat fell seam

Keep the fabric pieces wrong sides together. 

Sew a seam with a 1/2 inch seam allowance. Mark 1/4 inch to the inside on one of the seam allowances.

Now trim the seam allowance on one side  to 1/4 inch ; ( this will be kept underneath the other seam allowance, when you finish the whole thing)

(For a narrower flat fell seam make the seam allowance 1/4 inch and the trimming 1/8 inch ; but I prefer the wider one for all seams – it is easier to sew and looks nice too.)

Press the seam allowances to the side of the smaller seam allowance (which you just now trimmed)

Now fold the top seam allowance over this trimmed seam allowance. Press in place. it will look like this.

Press the whole thing to the side of the trimmed seam allowance, as you did earlier.

You now will have to top stitch over this fold.

You have to Edge stitch over this along the fold – you will be sewing through all the layers from the top. Make sure that you are sewing equidistant from the fold. 

This your flat felled seam.

Some notes on using this seam : Do not use on very very thick fabrics – remember you have to stitch through those fabric layers. or you can go for the fake fell seam.

Fake Flat fell seam : If you want to have the appearance of this seam ( and get its strength) but do no want to go to all that trouble, just press the seam allowance of a normal plain seam to one side and top stitch parallel to the plain seam. Ta da, the look of a flat felled seam.

Related posts :Sewing tip proof strong seams for clothes ; 17 Different types of seams; Plain Seam ; French Seam