Will the System Perform? Mock-Up
Testing Answers The Question
n the ever-changing world of com-
While sealants can be used as a bar-
mercial glazing,mock-up testing has rier against air,water,thermal,etc.,they
become a must for many projects.
The complexity of the systems,con-
are also used for structural purposes.
“If there’s a sealant failure it could lead
cern about failure, as well as a need for to problems in any of those categories,”
familiarity with the process all have Runkle says,explaining this could result
contributed to growth,” says John Run- in a water leak into the building.
kle, vice president, building sciences
with Intertek-ATI in York, Pa.
“But on the structural side, numerous
systems rely solely on the sealant to ad-
This type of testing ensures the com- here the glass to the backup structure (i.e.,
pleted project will perform as intended. SSG),”he says.“A failure in that joint could
Failures could occur for many reasons. lead to glass breakage or falling out.”
Some are more serious than others,
particularly those related to structural cladding system design development is
silicone glazing (SSG). done via engineering analysis, such as
Forner adds that most of the
Tammy Forner, senior associate, predicting structural behavior, rates of
manager – northeast,for CDC in Farm- thermal transfer, etc.
ington, Conn., says in her experience,
“It’s in the assembly and installation
sealant installation and adhesion issues of the engineered components of a
contribute to about three-fourths of cladding system where control of the
process can be lost,” she says.“A critical
Those result overwhelmingly in un- component of assembling the compo-
desirable air infiltration or water pene- nents into a fully functioning cladding
tration,” she says,explaining that issues system depends on workmanship while
can include seals being missed during installing construction sealants, either
installation or assembly; use of incor- as joint adhesives/fillers or as structural
rect sealant; an insufficient amount of adhesives.This elevates the importance
sealant; or missed/improper tooling.
of pre-construction adhesion and com-
Forner also attributes two-thirds of patibility testing by the sealant manu-
the sealant problems she’s seen to in- facturer on all substrates to which
stallation-related problems and one- sealants will be applied, as well as the
third to adhesion issues.
According to Runkle,those sealant is- blers and installers of cladding systems.”
sues include failures of adhesion or co- So what happens after a mock-up
skill and professionalism of the assem-
hesion failures. A cohesive failure, he fails and what are the steps to resolve
says, is a failure within itself, while ad- the issues?
Mock-up testing can help projects hesive failures occur at the bond line
avoid a number of issues in the field. between sealant and substrate.“Adhe- small scale testing is done.
These can include (from top to bottom) sive issues often are workmanship re- “You try to see if it’s an isolated oc-
Runkle says macroscopic testing or
adhesion failure of the EIFS finish coat lated. A cohesive concern is often currence or something pervasive and
to base coat (horizontal) as well as related to improper joint geometry.This we use this testing to determine that.
cohesive sealant joint failure (vertical); can be a function of installation,but it’s Then it’s typically a remove-and-replace
failed sealed joints, likely due to a also a little higher weighted on the de- situation and you re-test.”
chemical reaction; and cracking or sign side … it’s hard to get the ideal
Forner says that the resolution of
crazing in the sealant joint.
geometry and that can lead to failure.” sealant issues is dependent upon a
USGlass, Metal & Glazing | March 2016