Chapter 10 Review 1. A cavity wall prevents penetration of water through a masonry wall by putting a continuous vertical airspace between the outer and inner wythes of masonry. At the bottom of the cavity, the water is caught by a flashing and drained out through weep holes. The most critical part of cavity wall construction is keeping cavity clean and free of mortar droppings and other obstructions. 2. External flashings should be installed at intersections of masonry walls with roofs or decks. Internal flashings should be installed wherever water might penetrate, such as over lintels and shelf angles, under copings and sills, at intermediate floors that bear on the wall, and at the base of the wall. The function of internal flashings is to catch and drain any water that penetrates the wall. 3. Weeping holes should be installed just above each internal flashing, in the outside wythe of the wall. Their function is to drain water that accumulates over the flashing. They may be constructed by leaving out the mortar in head joints, laying
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