Copyright Goodheart-Willcox Co., Inc. 244 Section 4 Techniques moisture. Weep holes must be clear of obstructions and placed directly on the flashing to function properly. If excessive moisture accumulates behind the brick, as the moisture migrates through the brick, it will accumulate on the exterior surface creating efflorescence stains. A more damaging occurrence is when moisture inside the brick freezes causing spalling. See Figure 12-57. If the process of freezing and thawing continues over a period of time, the brick begins to fall apart. Weep hole devices come in many different sizes and shapes. Figure 12-58 shows two examples of weep hole configurations. In the past, weep holes or voids were formed by leaving a head joint out to create a means to drain moisture from the interior of the wall structure. The normal practice is to install weep holes every 16″ O.C. One type of weep hole device is made of plastic or sim- ilar material with a stainless steel screen to allow moisture to escape but stops insects from entering the structure. Another method to remove moisture is to use a special- ized rope material usually made of cotton that wicks mois- ture from behind the wall to the exterior surface. Tooling Weather tightness and textural effect are the basic considerations of mortar joint finish selection and execution. Properly striking or tooling the joint helps Code Note Weep Holes Refer to local building codes or construction specification to determine correct procedures and installation practices for the specific project being constructed. the mortar and masonry units bond together and seal the wall against moisture. The concave and V joints provide the most weathertight joints. Joints should be tooled when the mortar is thumbprint hard. Tie Placement/Joint Reinforcement Both wythes of masonry must be properly tied together in a quality constructed cavity wall. The primary Itsvan Balogh/Shutterstock.com Figure 12-57. An example of spalling caused by moisture inside the brick during freeze/thaw cycles. Timothy L. Andera Figure 12-58. Two different types of weep hole configurations. Both weep holes are directly above the flashing. A—A vertical weep hole device made of plastic that is positioned in the head joint. It has a metal screen to stop insects from entering wall. B—A cotton rope material installed in a plastic tube to collect moisture and transfer it to the exterior. A Vertical weep hole B Cotton rope material