I am enclosing an existing garage door opening to make it a wall with a window in it. I know how to frame it out, and I know that the exterior side of the wall will be finished with "carsiding" (tongue and groove) to match some other wood on the garage. Do I put something (plywood? OSB?) on the exterior studs before installing the siding, or just apply the siding directly to the studs? I will be having foam insulation sprayed on the interior, so the foam will be sprayed directly on whatever the back of my exterior wall is, if that makes sense.