A laminated board is secured to the inner wall of a cavity wall construction to establish a defined spacing between the inner and outer walls and prevent excess mortar from bridging to the inner wall. The laminated board has a series of spaced sockets into which fasteners may project into the face of the inner wall or framing thereof to secure the outer wall. The board is installed prior to the construction of the outer wall and establishes a minimum spacing or gap between the walls based upon the thickness of the board. The outer wall is constructed immediately adjacent to the outer face of the laminated board. The board is impervious and eliminates bridging by the mortar, eliminates transfer of bulk water from the exterior finish to the inner wall and provides an air conduit to exhaust even the minimal amounts of vapor that will occur in the cavity.