Thickness problem?

Trying to model a Shirt but noticed a geometry problem. The main body of the Shirt should really be 0 thickness (single polygons) and some other parts need much more thickness, the problem is when attaching the geometry together then usig Subsurface modifier causes problems. (hopefully the photo will explain) …

Except, even thin cotton doesn’t have 0 thickness. In life, there are no two dimensional objects (except possibly at a quantum level or in Star Trek)

Thanks for the reply but want to point out that the thinnest part of the shirt is only 1 stitch thick where the other are much more, so 1 poly thick will do else would have double of the stitches.

Fake it. Only thicken the edges where needed and just leave them open where they are out of view.