Masonry Veneer
When masonry veneer is used for cladding, the foundation must include a supporting ledge or offset wide enough to allow a space at least 25 mm (1 in.) between the masonry and the sheathing membrane (Figure 113). Insulating concrete form (ICF) foundations may use a reinforced flare at the top of the foundation to support the weight of brick veneer (Figure 114). The base flashing must extend from the outside face of the wall over the top of the ledge and at least 150 mm (6 in.) up the wall behind the sheathing paper. Use corrosion-resistant metal ties nailed to the studs and embedded in the mortar joints between the masonry to tie the veneer to the framework. When fastened to every other stud, they are usually spaced 800 mm (32 in.) apart horizontally and 400 mm (16 in.) vertically. Alternatively, when fastened to every stud, they may be spaced 600 mm (24 in.) horizontally and 500 mm (20 in.) vertically, or 400 mm (16 in.) horizontally and 600 mm (24 in.) vertically, depending on the stud spacing.
Lay brick or stone in a full bed of mortar. Ensure mortar does not drop into the space between the veneer and sheathing where it will obstruct the cavity behind the veneer. Tool outside joints to a smooth finish to provide maximum resistance to water penetration.
Weep holes serve both venting and drainage functions. They should be placed not more than 800 mm (32 in.) apart in the bottom course of the masonry veneer and above-grade windows and doors. This can be done by omitting part of the mortar from the vertical joints, or by inserting plastic tubes in the joints.
Masonry veneer should be at least 75 mm (23⁄4 in.) thick and masonry less than 90 mm (31⁄2 in.) thick must have unraked joints.
Bricks should be hard, absorb little water and be manufactured for exposure to the weather. Stone veneers should be materials that are known to be durable.
Masonry laid during cold weather should be protected from freezing until after the mortar has set. The temperature of the masonry and mortar should be maintained above 5°C (41°F) for at least 24 hours after installation.
Figure 113
Figure 114
Source : Canada Mortgage and Housing Corporation (CMHC)
