Where should the dew point ideally be located in an insulated wood wall?

The ideal location for the dew point in an insulated wood wall should be within the air barrier. Positioning the dew point here minimizes the risk of moisture condensing within the wall assembly. When the dew point is located at or beyond the air barrier, it helps to prevent moisture accumulation within the insulation and wall materials, which can lead to mold growth, wood rot, and reduced insulation effectiveness.

In this configuration, the air barrier also acts as a protective layer, reducing the infiltration of warm, moist air that could otherwise reach colder surfaces where condensation could occur. Keeping the dew point within the air barrier ensures that any moisture present is less likely to cause damage, maintaining the integrity and durability of the wood wall assembly.

Having the dew point inside the insulation layer, outside of the wall, or at the center of the wall would all potentially allow for condensation within the wall's structure. This could undermine both the insulation's performance and the overall structural integrity of the wall, leading to severe long-term issues.