Page 251 - Masonry and Concrete

Masonry Veneer

250 CHAPTER SEVEN

wall. Anchored veneer is secured by metal anchors attached to either
a solid backing wall or a stud wall. An anchored masonry veneer sup-
ports its own weight, resting directly on the slab or foundation wall.
Building codes regulate the design of masonry veneers by prescriptive
requirements based on empirical data. The CABO One and Two Fam-
ily Dwelling Code requires that masonry veneers be supported on non-
combustible construction, and limits the height of masonry veneers
over wood frame backing walls to 30 feet above the foundation with an
additional 8 feet at gable ends.
Anchored masonry veneers transfer lateral loads to the backing
wall through metal anchors and their fasteners. Flexible veneer
anchors permit slight horizontal and vertical movement parallel to
the plane of the wall but resist tension and compression forces per-
pendicular to it. Corrugated sheet metal anchors are typically used in
residential construction. These should be 22-gauge galvanized steel,
7 8 in. wide 6 in. long. Corrosion-resistant nails should penetrate
1
wood studs a minimum of 1- 2 in., exclusive of sheathing thickness.
Galvanized or stainless steel screws should be used to attach corru-
gated anchors to metal studs. Corrugated anchors are relatively weak
in compression compared to commercial veneer anchors, and they
provide load transfer only if the horizontal leg is properly aligned in
plane with the mortar bed joint and one of the two fasteners is posi-
tioned at the 90° bend (Figure 7-1). Anchors randomly attached to the
backing wall and bent at odd angles to fit into the mortar joints are
ineffective. Masonry veneer anchors must be embedded in the mortar
1
joint a minimum of 1- 2 in. for lateral load transfer and have a mini-
5
mum mortar cover of 8 in. to the outside of the wall to prevent cor-
rosion of the metal (Figure 7-2). Anchors should be placed within the
mortar so that they are completely encapsulated for maximum pull-
out strength. An anchor that is placed on the dry masonry and
mortared only on top has only about half the strength of an anchor
that is properly embedded.
Masonry veneer is typically connected to metal stud frames with 9-
gauge corrosion-resistant wire anchors hooked through a slotted con-
nector for flexibility (Figure 7-3). Anchors are attached to the studs
with galvanized or stainless steel self-tapping screws. The use of brick
veneer over metal stud backing is relatively recent in the long history
of masonry construction. For one- and two-story buildings with lim-

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