If you ever would like to put splits in a tee shirt, I would recommend using a herring bone tape which will be featured on the inside of the split.

Tee shirts are usually put together with a four thread over locker, which means no seam allowance, therefore to open out the seam and turn a section back would not look that great, plus the split will probably roll because there is nothing of substance to hold it back.

Leave some tape hanging over the hem for turn back and sew the herring bone tape on so that it is lying over the top of the right side of the fabric.  This way when you lay the tape flat there will be no bulk.  Make an upside down “V” at the top of the tape with the excess tape underneath, and then sew down the opposite side.

Turn the tape back to the wrong side and fold the excess at the hem under and sew around the outer edge of the tape.

Happy sewing

Judith aka genie