Re-insulate from the outside with a vapor barrier or not?
I live in northern Indiana with a wide array of temps and weather conditions. Our home was built in 1973 and this past winter I repaired some drywall and noticed 1- no vapor barrier and 2-huge voids in the cellulose insulation — some entire stud areas missed completely.
So my plan is to re-insulate from the outside, since all my rooms have been recently smoothed (texture) and finished. I plan to use unfaced R-15 fiberglass and R-3.3 (1/2-inch) foam board in place of the 1/2-inch black tar board on the outside as sheathing.
I wondered if I should try to add a vapor barrier from the outside, tucking the film into the wall cavity (against the drywall) and around the stud then lay in the batt and covering with foam board. But I am worried I will create a wet wall with no way for it to dry. Or should I leave out the inner vapor barrier — or the foam board — or is it all ok?
I have called a half dozen insulating companies and all say either vapor barrier is not needed or it is a horrible idea. I just need a clear direction to proceed.
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