If a Grace Ice and water shield WRB (with no water vapor permeability) has been applied to the face of the Plywood on a timber frame building, what EIFS detail should be used –  should there be a need for a drainage plane (mat) between the WRB and Insulation board? 

Part two of this question: Let’s assume the thickness of the insulation board (EPS) is at least 4 inches. Will this thickness be adequate to prevent moisture condensing in the wall cavity/internal plywood face? Especially concerning during the cold climate – NY winter months. 

Your comments are appreciated.