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.

Bedroom exterior wall showing framing, plastic sheeting, and original siding

1 Answer 1


Actually, the siding screwed into the metal skin is fine if the proper screws were used.

Any insulation is a help. Your 1" ridged is good , but I would go with R13 kraft faced batts. Plentiful at most any home store. Your framing is probably 2x3, so it would be compressed and loose some efficiency. The alternative is R 6.7 batts which are more difficult to find and about the same price.

An aside, as an owner of mobiles myself, If you haven't replaced the aluminum wiring yet, do so now that the walls are open. Also if you have a Federal Pacific Breaker box, change it for the sake of everyone's safety.

  • Galvanized screws were used. Up until this afternoon, I had R13 kraft-faced batts installed. You're right about the 2x3. The R13 was putting up a lot of resistance against the 1/8 paneling I'm installing. I pulled that out in favor of rigid, maybe too hastily, but it was only the wall you see in the photo thus far. General Electric box. No Federal Pacific here. Haven't seen any aluminum wiring, but I'll look more closely. Thanks for your response!
    – David
    Commented Jun 25, 2023 at 21:46
  • @David, Sound like you have things under control. I use 1/2 " drywall or durock when refacing my walls so the resistance is not an issue for me.
    – RMDman
    Commented Jun 25, 2023 at 21:49

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