Possible to Solidify only selected faces?

Is it possible to solidify only selected faces? I need to have a single mesh (it’s a tank top). But I need the neck area to be “solidified”.

Whats the best way to do this? I was hoping to select the faces, and add the “Solidify” modifier, but that does the whole mesh.

Create a vertex group of the disered vertices. You can select that group then in the solidify modifier options.

Maybe post an image, of what you are doing, sounds like a pretty strange approach to use the solidify modifier for that

I’m retrofitting clothing models to characters for real-time (unity), so I have to keep polygons to a minimum - so models are single sided. However, they also have to be a little bit offset from the character model, so when the character is animated, there is no bleed through (due to some significant differences in topology). Due to this offset, I sometimes need a lip and some back-facing polygons, to avoid “straps going nowhere” issues when viewed at certain angles. It’s hard to post a pic showing the specific issue, because it’s mostly noticeable in animations. But your help got me going. Thanks!