Weep systems in use include wicks, oiled rods, weep tubes, open head joints, and vents. BIA does not advocate one type of weep system over another. Wicks should be spaced at 16" o.c. with the remainder of the weep systems spaced at 12" o.c. Rope wicks can be made from cotton sash cord. Drainage materials used at the bottom of the cavity are most effective for open type of weep holes like open head joints, weep tubes, etc., however it could be used with rope wicks. It is important to maintain a clean, open cavity for weep holes to function properly. If mortar droppings are anticipated, then it is best to detail a drainage material that will catch any mortar like pea gravel or mesh. For additional information on weep holes, see Technical Notes 7.