I found myself with carpenter ants showing up in my house mid February this year. With 6" of snow still on the ground I knew that they were in my walls. So I ripped out my drywall in my living room and found the nest, along with leaking and poorly install vinyl siding. Anyhow, I got looking at the way my walls were put together and wonder if the way mine is done is right, or if it is a slight of hand for the inspectors when the house was built. My walls, going from interior to exterior: drywall, 2x4 studs and R11 insulation, foil faced foam board and then the vinyl siding. The way I have always seen homes built (my parents built one when I was a kid) is that they go: drywall, 2x4 studs and insulation, wood sheeting, foam board, tyvac house wrap, then the siding. I know I need to reside the house, but do I need to pull down the foil board, and install real wood sheeting? Also wonder about upgrading the insullation from R11 to R13 (looked for R15 rolls or bats @ big box stores, but none have it here in lower mi.) Is it worth the hit to go to R13? Thanks in advance!