Page 130 - Masonry and Concrete

Understanding Masonry
129
UNDERSTANDING MASONRY

4.7.3 Flashing and Weep Holes
Masonry flashing can be made of metal, rubberized asphalt, sheet
membranes, and other materials. It is used to control moisture in
masonry walls either by keeping the top of a wall dry, or by collecting
water inside a wall so that it can be drained out through weep holes
(Figure 4-30). Rubber and plastic flashings are most often used in res-
idential work because they are inexpensive and easy to work with.
The thickness of these membrane flashings should be sufficient to
prevent puncturing or tearing too easily with the point of a trowel.
PVC flashings may become brittle over time and not serve the life of
the building.
Weep holes are usually formed by leaving the mortar out of some of
the mortar joints between units, but cotton wicks may also be used.
Cotton wicks provide slower moisture drainage, but they are the least

HOUSE WRAP OR
FELT OVERLAPS
TOP OF FLASHING

FLASHING
COLLECTS
WEEP HOLE MOISTURE
FOR MOISTURE
DRAINAGE

FIGURE 4-30

Flashing and weeps.

Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2004 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.