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Bonded Pull Tests: Not Just for Roof Membranes Anymore A Review of ASTM E2359

May 15, 2011

Those of us who have been
involved in building envelope
consulting for any period of
time have either performed,
observed, or read about the
bonded pull test for roof membranes.
These tried-and-true tests are some
of the best ways to perform a roof test in the
field to measure the uplift and negative
pressure capacity of a roof system. What
about the vertical surface of the building
envelope and the outward or negative load
capacities of these systems? While the construction
of many exterior cladding systems
prevents this type of test, an exterior insulation
and finish system (EIFS) is built in
such a way that a bonded pull test can be
performed that will accurately evaluate the
outward load capacities of the EIFS system.
The results of such procedures can be helpful
in determining the negative wind load
capacities of EIFS assemblies.
INTRODUCTION
Several of the bonded testing procedures
for roofs include those covered in FM
Global Property Loss Prevention Data Sheet
1-52; ANSI FM 4474, American National
Standard for Evaluating the Simulated Wind
Uplift Resistance of Roof Assemblies Using
Static Positive and/or Negative Differential
Pressures; and the Florida Building Code’s
Roofing Testing Application Standard (TAS)
124. Presently, all these standards are fairly
similar in procedure and purpose. They
assist in determining if the roof system in
the three different zones of a roof can withstand
the code-required calculated wind
uplift pressure of that particular building in
its respective zone.
Design wind pressures for a building
based on code are typically calculated utilizing
the American Society of Civil Engi –
neers’ ASCE 7, Minimum Design Loads for
Buildings and Other Structures. ASCE 7
assists in calculating the negative pressures
for Zones 1, 2, and 3 on the roof, as well as
positive and negative pressures for Zones 4
and 5 on the exterior walls.
In designing and specifying different
components for exterior wall systems, it is
important for designers to ensure that these
components can withstand code-required
loads. Whether the component is the curtain
wall, windows, sliding glass doors, or
exterior wall cladding (including EIFS), different
field tests may be required during
installation (or many years after a system is
installed) to evaluate the performance of or
detrimental effects to these building components.
ASTM E2359, Standard Test Method
for Field-Pull Testing of an In-Place Exterior-
Insulation-and-Finish-System-Clad Wall As –
sem bly, is the most valuable method for
determining the resistance of a section of
EIFS.
FRAME AND APPARATUS
The first part of this procedure requires
having or constructing a pull test frame.
Similar to the roof-bonded pull tests, a
frame is required to pull the test specimen
away from the wall. The most common roof
frame is a tripod with a winch and load cell
at the top that pulls the roof specimen from
the roof upward to simulate the negative
uplift pressure the system could undergo.
When dealing with a vertical surface, one
must also deal with the weight of the frame
against gravity and other factors that make
the procedure vary slightly.
While the frame for an exterior wall is
similar, there are some different considerations
than those for a roof frame. The pulltest
frame for the ASTM E2359 procedure is
typically constructed and fabricated from
metal (wood is also acceptable by the standard)
and must be able to apply a concentric
force to the test specimen while distributing
the reaction force to the adjacent wall
components. This is typically done with flat
plates on the exterior of the frame that are
outside the size of the test specimen. ASTM
E2359 (Figure 1) shows a detailed view of a
typical frame. The frame should also be
constructed and provided with a wormgear-
style winch with a strap or cable to
apply the load in a controlled manner to the
specimen. This is measured with a load cell
and digital load force gauge so that the
loads can be measured and recorded
throughout the test procedure.
Once the components of the frame are
constructed and ready for use, a specimen
must be adhered to the EIFS wall in such a
way that it can be connected to the pull test
frame, winch, and load cell to perform the
bonded pull tests. This process is completed
by using 2- x 2-ft. wooden panels comprised
of ¾-in.-thick plywood. These panels
must be precut prior to performing the procedure,
with one required for each pull test
performed, as the plywood will be bonded to
the EIFS wall and will become a part of the
6 • IN T E R FA C E DE C E M B E R 2011
sample once the test is performed. The plywood is adhered or bonded to the
surface of the EIFS wall with polyester adhesive, adhesive expanding foam,
or quick-reaction epoxy cement. In addition, another ¾-in. plywood bolting
panel will need to be cut and will move from test location to test location.
This second panel is connected to the plywood panel once it is adhered to
the EIFS wall by fastening twelve #12 screws, 1½ in. long, in a prescribed
pattern (see Figures 2 and 3 from ASTM E2359).
TEST PROCEDURE
To begin the process, use a metal detector or rebar locater to locate the
metal studs within the wall assembly. For typical stud spacing that is going
to be less than 24 in., the specimen panel will be spaced and centered over
two adjacent studs. If fasteners were used to secure the foam in the EIFS,
locate the heads of the foam fasteners and arrange the specimen panel so
that it will evenly distribute the load across the specimen. Once the location
where the panel will be adhered to the wall is determined, outline the area.
At the outlines, the EIFS will need to be cut through the lamina, insulation
board, and underlying sheathing. A reciprocating saw works best to cut
through the EIFS without damaging the studs. If the EIFS is applied directly
to a masonry substrate, a circular saw can be used. It should be noted
Figure 1 – Pull test frame.
Figure 2 – Bonding panel.
Figure 3 – Bolting panel.
Photo 1 – Plywood panel
bonded to EIFS wall.
DE C E M B E R 2011 I N T E R FA C E • 7
that if the EIFS is applied to a masonry substrate,
the saw blade should be set at a
depth to extend ¹⁄₈ in. to ¼ in. into the
masonry.
Once the location is marked and cut,
adhere one of the 2- by 2-ft. panels to the
wall with the selected adhesive (Photo 1).
Sintolit Transparent Solid polyester, twocomponent,
knife-grade adhesive has been
found to work the best for bonding the plywood
panel to the EIFS. While there are different
types of expanding foam adhesives,
this author finds that often the plywood
panels need to be additionally secured to
the exterior wall with fasteners or other
means while the foam sets. The weight of the plywood panel
often overcomes the initial hold of the adhesive before setting
up. After installation of the bonding panel to the wall, a precut
bolting panel can be installed using the fasteners in the prescribed
pattern shown above. It can be seen from Figures 2 and
3 that a 1½-in.-diameter hole allows for the head of the bolt to
be installed in the bonding panel, and a ⁵⁄₈-in.-diameter hole is
installed in the bolting panel so that the load cell can be connected
to the center bolt (see Figures 4 and 5 and Photo 2).
Once the panel is set, the frame can be installed and the
load cell connected to the center bolt to start applying pressure.
The pressure for the test should be the cladding design wind
pressure (DWP) that was utilized during original construction,
or the DWP should be calculated using the appropriate building
code or ASCE 7. The frame should be installed centrally
around the test panels. It should be installed in such a manner
that the load cell is mounted in line so that the winch and
wire attachment can provide a concentric load to properly measure
a force load (see Figure 6 and Photos 3 and 4). The frame
can be heavy and can affect the test due to its weight on the
test specimen, so it is often required (as described in Note 7 of
the test standard) that a sawhorse, swing-stage rails, or extra
personnel be used to hold the frame until
enough load is achieved to make the frame
self-supporting (see Photo 5).
To start the test, an initial load of
approximately 10% of the cladding DWP
should be applied. This load should be held
for one minute with recordings of the loads
applied at the beginning of the load step, at
the end of the load step, and then after the
minute prior to going to the next load. The
test procedure should be continued by
applying increasingly higher steps with
each one 10% of the DWP until the specimen
fails. As stated above, the loads from
the force gauge should be recorded at the
beginning of the loading, at the end of the
loading, and after the one-minute hold prior
to going to the next load.
Once the specimen fails, the failure
method should be documented. The standard
defines five different types of failure
methods:
Figure 6 – Test arrangement isometric. 1) Face delamination, which occurs
8 • IN T E R FA C E DE C E M B E R 2011
Figure 4 – Plywood assembly.
Figure 5 – Detail of bonding and bolting
panel with bolt in center hole.
Photo 2 – Test panel fastened to bonded plywood panel with force
gauge in place.
when the face of the sheathing loses
bond or delaminates from the
sheathing core;
2) Fastener pull-out from the stud,
which occurs when the fastener
releases from the substrate;
3) Fastener pull-through, which occurs
when the head of the fastener pulls
through the sheathing, insulation,
or substrate;
4) Lamina release,
which occurs when
the EIFS base coat and finish coat
release from the underlying thermal
insulation board; and
5) Thermal insulation board failure,
which is cohesive failure within the
thermal insulation board (Photo 6).
INTERPRETATION OF
THE RESULTS
The final load
recorded from the
force gauge is the
failure load ap –
plied on the specimen.
Once the
specimen has
failed and been
removed and the
failure load is
recorded, the tributary
area of the
specimen should
be calculated. The
overall tributary
area is calculated
by measuring the
stud spacing over
which the speci-
Photo 3 – Pull test frame installed against wall.
Photo 4 – Pull test frame centered to provide
outward pressure on bonded panel.
DE C E M B E R 2011 I N T E R FA C E • 9
men was applied and then measuring and
adding half the distance to the studs on
either side of the specimen opening. This
theoretical width is multiplied by the height
of the specimen to calculate the tributary
area. This process should be performed for
each of the specimens that are tested on the
project. To calculate the test pressure for
each specimen, divide the maximum sustained
load recorded on the force gauge by
the theoretical tributary area to obtain the
force per area.
Example: Testing is performed on a
specimen with a failure load of 304 lbs. A
test specimen is taken with the height being
24 in. and the stud spacing being 16 in. The
tributary area is (height x theoretical width):
Width = 16 in. + (16 in./2) + (16 in./2)
= 32 in.
Tributary Area = [(24 in. x 32 in.)/144] = 5.33 sq. ft.
Force Per Area = (304 lbs./5.33 sq. ft.)
= 57.4 p.s.f.
Interpretation of these results as
described in the standard can be highly
subjective. The test standard does not claim
to “replace education or experience and
should be used in conjunction with sound
engineering practice and professional judgment.”
In the example above, the test specimen
was taken in Zone 4 of a new building
in Tulsa, OK, where the calculated DWP for
Zone 4 was a negative 39 p.s.f. For this
example, it was concluded that the test
specimen was able to withstand the DWP
for this project.
CONCLUSION
As many of us read
and understand this
stan dard, we are reminded
of the bonded pull
tests that we have seen
or done numerous times throughout our
careers working on roofs. Those types of
procedures could possibly have been the
inspiration for ASTM E2359. While many
types of exterior cladding systems cannot be
analyzed in this fashion, an EIFS wall typically
can. As designers, we need to ensure
that we are specifying products and systems
that have been tested and certified to
meet the code-required loads to which we
are bound. In addition, in evaluating building
failure or performance of in-place
assemblies, these types of evaluation procedures
can be very valuable in helping with
forensic studies and surveys.
The ASTM E2359 procedure can be performed
on new and existing construction
and will evaluate the entire assembly of the
EIFS to determine the failure method of the
system to help pinpoint the source and reason
for the failure. A thorough knowledge of
the standard and EIFS should be understood
before attempting to perform this test
procedure. While it should be used in conjunction
with experience and education to
determine outward load capacities, this test
standard is the most valuable tool for assistance
in determining the negative wind load
capacities of an EIF system.
Robért Hinojosa is the principal engineer and owner of
Building Engineering-Consultants, Inc. (BE-CI), an engineering
consulting firm specializing in investigation, repair,
design, and restoration of building envelopes. The firm is
based in Destin, FL, with offices in Gulf Shores, AL; Houston,
TX; and Tampa, FL. BE-CI and Hinojosa perform extensive
testing on existing construction for forensic purposes, as well
as performance testing on new construction throughout the
U.S. and the Caribbean. Hinojosa has a BS in civil engineering
from Texas A&M and an MBA from the University of Houston. He is a registered professional
engineer in eight states and a construction document technologist (CDT)
through the Construction Specifications Institute, a certified EIFS inspector (CEI)
through the Association of the Wall and Ceiling Industry ( AWCI), and a Level I certified
infrared thermographer (CIT) through the Infraspection Institute. Robért is a member
of RCI, CSI, ASCE, and he is the current Region II director of RCI, Inc.
Robért Hinojosa, RRC, RWC, REWC, RBEC, PE
10 • I N T E R FA C E DE C E M B E R 2011
Photo 5 – Test procedure in process. Additional
personnel used to hold the frame in place until
the load is applied.
Photo 6 – Test specimen after pull test
exposing the metal stud framed wall.