Abstract: A mortar and debris collection device for a cavity wall construction has a non-water absorbent body formed with circuitous paths therethrough making the body water-permeable. The collection device has a porosity sufficient to permit water to pass therethrough but insufficient to permit mortar and other debris to pass therethrough to weep holes or other water channels covered by the collection debris. The device may be freely placed on the wall base within the cavity to cover the opening of a weep hole, or may also be placed on existing wall ties within the cavity.