Essentials of
Masonry

PROTECTING THE BRICK AGAINST WEATHERING

Freezing and thawing breaks down the bond, which is the only type of weathering that affects brick. Therefore, the resistance of brick walls to weathering depends on their resistance to water penetration.

3-29. Tooling and Caulking. You can protect walls against moisture by making sure that joints are well-tooled and by caulking around door and window frames.

3-30. Flashing. The installation of flashing, strips of metal or roofing paper that is bent to fit mortar joints, is another method of protecting the brick against water penetration. Flashing keeps water from penetrating and directs it to the wall exterior. It is usually placed at the head and sill of window openings in some buildings and at the intersection of the wall and the roof (Figures 3-33 and 3-34).

Figure 3-33. Flashing at the head and sill of window openings

3-31. Materials. The most common flashing materials are copper, lead, aluminum, and bituminous roofing paper (paper that has been coated with asphalt or a similar water-resistant substance).

3-32. Installation. Spread a 1/2-inch-thick bed of mortar on top of the brick and push the flashing firmly into the mortar. Place the brick or sill that goes over the flashing into a l/2-inch-thick bed of mortar spread on the flashing itself (Figure 3-33). Turn up the edges of the flashing to prevent drainage into the wall. Fit the upper end of the flashing into the groove of the raggle block and caulk it (Figure 3-34).

 
Figure 3-34. Flashing at the intersection of the wall and the roof

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