Adding ISO board under siding??
I have a 160 year old ballon framed farm house in NE Pennsylvania. I want to add insulation to the exterior walls. The current wall profile is 1/2″ sheet rock, 1.5″ foil faced ISO board, 1.5″ verticle rough cut planks, wood lap siding. Most of the siding is original and is very weathered but has no rot issues whatsoever. Can I add ISO board under the siding or will I run into moisture problems by having 2 vapor barriers??
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