I own a 1960s mobile home in Michigan and am in the process of a complete renovation. Until now, I've used contractors, and as a bit of background to my question, one talked me into putting up rigid foam insulation over the original metal siding, then putting installing vinyl siding over that. All this was in the interest of cost savings.
Slight aside, the vinyl siding was screwed in (once they realized nails weren't going into anything) and is holding only onto the original metal siding. It seems lousy, but I digress.
I've taken over and want to begin finishing the interior walls. I've removed the insulation, and all that remains is the original vapor barrier on the interior side of the original siding. It's not a perfect seal by any means.
So, from the outside in, we have vinyl siding > rigid foam insulation > original siding > vapor barrier/plastic sheet > framing.
My question: Is insulating the interior the right move? And if so, should I be adding an interior vapor barrier? I had planned to install 1" rigid insulation sealed with spray foam.