A split side seam is a nice feature that adds a bit of visual interest as well as some wearing ease to a straight-hemmed garment, and flat-felling is a smooth and clean finishing technique for seams; but how to manage the awkward joining point between the two?
Marie Coffin and knj09705 both asked about the transition between the flat-felled seam and the split side seam on Sam’s shirt… thanks for showing an interest! and since I happened to making another shirt hot on the heels of the previous one I snapped a few pictures to demonstrate how I did it…
btw: I’ve checked out some of the better rtw menswear shirts and there’s a choice of finishing methods. So the following is not the only way to construct this feature, but this is the way I chose this time. I wonder… is there even a “right” way?
Stitch the seam down to the point at which the slit is to start. I left an unfinished length of 10cm for the side seam splits on both of these shirts…
Press the seam open, and and the seam allowances of the split.
So in this case, the flat felled seam of this shirt is continuing from the split, right up the side seam and continuing right down the length of the sleeve to the wrist opening. The rather weird picture below is attempting to show the side seam and sleeve seam allowances pressed open all in one continuous length; correspondingly, the seam allowance will be flat-felled all the way along this seam as one continuous length.
Decide which side of the seam allowance the seam will be flat-felled onto; again, after checking out rtw menswear shirts I’ve noticed there doesn’t seem to be an accepted convention here. I’ve randomly decided for the seam allowances to lie against the shirt back.
Trim this seam allowance to half its current width, with the trimming tapering off for the last couple of centimetres to the level of the slit. Also, snip into the seam allowance of the other side to the endpoint of the side seam (pictured below). Leave both slit seam allowances untrimmed.






































































