Flip certain surfaces

A simple question (I hope):

I have a bunch of imported surfaces that are not oriented as I would need them to be and I am wondering if it’s possible to flip them so that their normal vectors point “outside” of the breps on which these surfaces are located.

That is - the surfaces on the right side of my screenshot are oriented correctly and the left ones are the ones that I need to flip.

Does anyone have a tip on what would be the best way of doing it?

I was thinking of using the Flip component, but with my limited GH knowledge I can’t seem to be able to figure out how to select only the nearest faces of the Breps for the Flip Guide parameter.

Flip Surfaces.gh (19.7 KB)

Your geometry is not internalized.

If the surfaces can be joined into a ‘Closed Brep’, all the face normals will be outward.

Thanks. My bad, I’ve just replaced the file.
My surfaces need to stay separated more or less the way they are right now. Or maybe I don’t quite follow.

Flip Surfaces_2023Nov6a.gh (30.4 KB)

P.S. Small changes, added Extrude:

Flip Surfaces_2023Nov6b.gh (28.4 KB)

Oh wow, thank you so much! That works perfectly.