Failure Number 14 Improper
Veneer installations are classified
as adhered veneer and anchored veneer.
All veneer weighing more than 15
pounds per square foot is required to be anchored veneer.
Failures occur with anchored veneer
when adhesives used, fail and when mechanical anchoring systems are not in
conformance with minimum industry standards.
Failures have occurred with adhered
veneer assemblies due to lack of coordination with the lath and plastering
contractor installing the scratch and brown coat for the tile and stone veneer
assemblies. Soaps and surfactants used in plastic cement used by a lath and
plastering contractor will bleed through and discolor limestone and marble.
Plastic cement is a weaker mix than our ANSI A108.1 requirements. The purpose
claimed by the lath and plastering contractor is to facilitate blowing the
mortar on the wall instead of using trowel applied method to be installed
through ANSI 108.1.
Lath and plastering contractors want
to install #15-screeds which serve to control shrinkage cracking of the scratch
and brown coat. The correct screed should be double casing beads over double
studs or #40 expansion joint screed when the screed is installed by the lath
and plastering contractor. The tile industry ANSI A108.1 does not address
screeds and assumes the tile and stone contractor is using wood float strips,
and removing the wood float strips and filling with caulking/sealants to work
at the expansion joint locations. Spacing for expansion joints are the same for
veneer as for horizontal assemblies.
Expansion joints are even more critical on south and west facing sides
of the building followed by the east side. The building code requires veneer to
allow for differential movement on building exteriors.
The lath & plastering
contractor wants to install stucco mesh or paper backed wire instead of 3.4
pounds per square yard expanded metal lath attached directly to studs or 2.5
pounds per square yard attached to studs with solid backing in between the stud
and the wire reinforcement. The wire installation cannot bridge over the
expansion joint location. Where full stone pattern is being installed, the
expansion joints must be coordinated with the lath and plastering contractor
for location to accommodate the full stone tile design.
Installation of stone as adhered
veneer includes washing the back of the stone to remove dust and changing the
water being used frequently.
Where a shade range occurs with the
stone selected, pre-blend the stone prior to delivery to the site for
All veneer installations require
grout, except at expansion joint locations.
There is no building code approval
for an ungrouted installation.
If sealers are used as grout
release prior to installation of tile, brick and stone, verification is
required if the painter will be installing sealers, and if the grout release is
compatible with these other sealers.
In California Title 24 prohibits
veneer to be installed above entrance and exit doors to schools and hospitals ½
inch and thicker in dimension. All materials ½ inch and thicker above door
installations in schools and hospitals are required to be anchored veneer.
The Uniform Building Code Chapter
14 requires full bond adhesion of veneer and even states back buttering of the
tile as part of the approved requirements. References to the word “tile” in the
code includes thin-brick and stones that are installed by adhesion.
Spot mounting adhered veneer is not
Stone and tile installed on
horizontal windowsills adjacent to reflective glass require expansion joints
more often due to the thermal heat buildup from the reflective glass.
Again the reminder waterproofing of
the windowsill and positive slope for drainage is required.
Masonry and concrete walls are
required to be heavily scarified to remove contaminants such as curing
compounds and form releases prior to direct bond installation.
Accent stone used on concrete
insets require expansion joints at all locations where the accent stone abut
In some parts of the United
States, acid rain is a concern and the
selection of the stone should consider the acid rain environment.
In some parts of the United
States, freeze-thaw conditions are a concern
and the selection of the stone should consider the freeze thaw conditions.