Page 273 - Masonry and Concrete

Masonry Veneer

272 CHAPTER SEVEN

prevents water from flowing back into the wall. The inside leg of the
flashing should turn up about 8 in. and be tucked underneath the felt
paper or house wrap membrane, or underneath the sheathing itself
(see Figure 5-25 in Chapter 5). If the backing wall is masonry, metal
flashing should be tucked into a mortar joint and membrane flashings
carefully adhered to the face of the block.
Flashing forms only half the moisture control system in a
masonry wall. By itself, flashing collects water that enters the wall,
but weep holes are necessary to provide the drainage mechanism that
lets the water back out again. There are several types of weepholes
commonly used. The most effective, but least attractive, are open
head joints. Because mortar is left out of the head joint completely,
the system has ample drainage and evaporative capacity for even the
most severe coastal rain conditions, and so can be spaced at intervals
of 24 in. Metal weephole ventilators and plastic grid type vents
improve the aesthetics of the open joint without obstructing free
drainage (Figure 7-24).

FIGURE 7-24
Weep hole vents.

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