Though tightly-insulated homes are more often a good than a bad thing, especially when it comes to energy efficiency, some worry that thick, double-walls makes vapor diffusion of interior moisture a bigger threat.
Researchers at the Building Science Corporation did a study of a double-wall home in Massachusetts, and found that cold sheathing does indeed get wet from a variety of sources: rain getting through bad window flashing, a roof leak, ground water wicking up through the foundation, and even from water vapor in the air.
After three years of analyzing temperature and moisture data, the analysts took apart the double-wall home and found that, despite high moisture, there were no signs of damage from mold or rot.
Read the full study at Energy Vanguard.