Evaluation of Metal Fasteners Corroded from Contract with Preservative-Treated Wood

Evaluation of Metal Fasteners
Corroded from Contact with
PreservativeTreated
Wood
MIKE ENNIS
Single Ply Roofing Industry
1100 Rosehill Road, Reynoldsburg, OH 43068
P: 6145787875
• Email:
m.ennis@mac.com
CARY BLACK
DuroLast
Roofing
STANLEY CHOINIERE
OMG Roofing Products
stanc@olyfast.com
ANDRÉ DESJARLAIS
Oak Ridge National Laboratory (ORNL)
yt7@ornl.gov
Proceedings of the RCI 25th International Convention Ennis et al. 75
ABSTRACT
This presentation will summarize work that was jointly funded by SPRI, the RCI
Foundation, and the National Roofing Foundation. The objective of this research program
is to determine the potential corrosive effects of new wood preservatives on
metal fasteners used in lowslope
commercial roofing systems, specifically those used
to hold the assembly to wood nailers.
The presentation will provide the following information:
1. Background on the potential issues of corrosion of metal fasteners in treated
wood.
2. Data developed in various laboratories that identify critical variables that initiate
corrosion of metal fasteners in contact with wood using various types of
preservatives, along with theories as to why this reaction is occurring.
3. Field data from the wood nailer location of lowslope
roofing systems located in
various regions of the country to determine if the critical parameters necessary
to initiate corrosion are present.
4. Recommendations as to the proper combination of fasteners and wood nailers
that should be used to prevent corrosion.
SPEAKER
Mike Ennis has been technical director for SPRI, the association representing singleply
roofing
manufacturers and component suppliers for three years. Prior to this, he worked for the
Dow Chemical Company and was the North American application technology leader for commercial
products in Dow’s Building Solutions business, where he led the development of new
products and applications. Mike has 32 years of building and construction experience to his
credit. Ennis is an RRC with RCI, Inc., and is a member of the board of directors of the Roofing
Industry Committee on Weather Issues (RICOWI) and the Cool Roof Rating Council (CRRC). He
is a member of ASHRAE and ASTM Committees D08, Roofing and Waterproofing; E05, Fire
Standards; and E60, Sustainability.
Ennis et al. 76
Proceedings of the RCI 25th International Convention
Evaluation of Metal Fasteners
Corroded from Contact with
PreservativeTreated
Wood
ABSTRACT
This report will summarize work
that was jointly funded by SPRI, the
RCI Foundation, and the National
Roofing Contractors Association
(NRCA). The objective of this research
program was to determine the potential
corrosive effects of new wood
preservatives on metal fasteners used
in lowslope
commercial roofing systems,
specifically those used to hold
the assembly to wood nailers and to
hold the wood nailers in place.
Due to environmental and regulatory
concerns, the wood industry
began using new preservative chemicals.
Concern has been expressed
that some of these new chemicals
may cause corrosion of certain types
of metal fasteners. This has been
observed in some instances. The
report will provide the following information:
1. Background on the potential
issues of corrosion of metal
fasteners in treated wood.
2. Data developed in various
laboratories that identify critical
variables that initiate
corrosion of metal fasteners
in contact with wood using
various types of preservatives,
along with theories as
to why this reaction is occurring.
3. Field data from the wood nailer
location of lowslope
roofing
systems located in various
regions of the country to
determine if the critical parameters
necessary to initiate
corrosion are present.
4. Recommendations as to the
proper combination of fasteners
and wood nailers that
should be used to prevent
corrosion.
INTRODUCTION
Preservatives are used to reduce
the potential for insect infestation and
rotting of wood products to extend the
service life of these materials.
Historically, the most prevalent
preservative used was Chromated
Copper Arsenate (CCA). Effective
January 2004, the Environmental
Protection Agency (EPA) banned the
use of this preservative for residential
use due to health and environmental
concerns. While the use of CCA was
still allowed for certain applications it
was more costeffective
for producers
to switch to more widely accepted
preservatives (Wieland, et al. 2004).
Two of the more common substitutes
for CCA that emerged were:
• Alkaline Copper Quartenary
(ACQ)
• Copper Boron Azole (CAB)
These materials rely on high levels
of dissolved copper to provide resistance
to insects and fungiinduced
rot. Standard industry tests for compatibility
indicated that metal
exposed to these new preservatives
had a higher level of corrosion as
compared to CCA preservative.
Thirdgeneration
wood preservatives
that rely on finely ground copper
in suspension, resulting in less free
copper ions, are being produced.
These new formulations include:
• Dispersed copper azole (μCAC)
• Micronized copper azole
(MCA)
• Micronized copper quaternary
(MCQ)
These new formulations claim
reduced corrosion rates compared to
copper solution treatments.
In addition to these copperbased
wood preservatives, there are also
boratebased
products available.
Borate is reported to be no more toxic
to humans than common table salt.
However, borate is very watersoluble;
therefore, wood treated with boratebased
preservatives is not suitable for
outdoor use.
The increased corrosion rate associated
with ACQ and CAB
preservatives
has the potential of being problematic
for the lowslope
commercial
roof industry. Preservativetreated
lumber is used as nailers for securement
of roof membranes and roofedge
products. The nailers are
attached to the building structure
with metallic fasteners, which are
then in direct contact with the preservativetreated
lumber. In many applications,
the wood nailer is also in
direct contact with a steel roof deck. If
corrosion of the metallic fasteners
were to occur and weaken the attachment
of the edge securement system,
the entire roof assembly would be
more susceptible to damage during
highwind
events.
Posthurricane investigations conducted
by the Roofing Industry Com mittee
on Weather Issues (RICOWI)
have consistently shown that in many
cases, damage to a lowslope
roof system
during highwind
events begins
when the edge of the assembly
Proceedings of the RCI 25th International Convention Ennis et al. 77
Figure 1 – Large retail building, Punta Gorda, FL, Hurricane Charley. Photo courtesy of RICOWI.
becomes disengaged from the building
structure. Once this occurs, the
components of the roof system (membrane,
insulation, etc.) are exposed.
Damage then propagates across the
entire roof system by peeling of the
roof membrane, insulation, or a combination
of the two (see Figure 1).
For this reason, a research project
was initiated by SPRI to determine if
corrosion of metal fasteners in contact
with ACQ and other new wood
preservatives was an issue in lowslope
commercial roofing applications.
This report summarizes the
work completed to make this determination,
which included laboratory
studies to identify the critical temperature
and humidity conditions necessary
to initiate the corrosion process
with various wood preservatives and
fastener types. The study also
involved determining the temperature
and humidity conditions that exist in
the wood nailer in various climate
zones. This data is then compared,
and conclusions are provided regarding
potential corrosion of fasteners in
wood nailers in lowslope
roofing
applications.
LABORATORY STUDIES
DUROLAST
ROOFING STUDY
Galvanic corrosion occurs when a
metal corrodes preferentially when in
electrical contact with a different type
of metal and both metals are
immersed in an electrolyte. The extent
or rate of corrosion is a function of
each metal’s electrochemical potential
and the efficacy of the electrolyte as a
media for ionic transport.
When two or more different sorts
of metal come into contact in the
presence of an electrolyte, a galvanic
couple is formed. The electrolyte provides
a means for ion migration
whereby metallic ions can move from
the anode to the cathode.
Gravimetric studies were conducted
at DuroLast
Roofing, Saginaw, MI,
to assess corrosion product weight
growth as a function of time of exposure
to different test environments.
CORROSION TESTS
The two experimental phases were
based on the American WoodPreservers
Association (AWPA
Standard E1294).
The first phase was an accelerated
test looking at corrosion of stainless
steel and ecoated
carbon steel fasteners,
and determining their
response in a controlled environment
in various lumber treatments. The
environment was extremely harsh
and likely unrealistic; however, it was
designed to maximize sensitivity to
corrosion rates.
The second phase was to assess
rates of corrosion at various temperatures
and relative humidity (RH) conditions.
Ennis et al. 78
Proceedings of the RCI 25th International Convention
TEST PROTOCOL lumber blocks with installed and 0.46 years.
Figure 2 – Parabolic rate corrosion growth vs. actual measurements.
Proceedings of the RCI 25th International Convention
• 1022 carbon steel ecoated
fasteners were used for the
experiments.
• The ecoated
fasteners were
weighed before and after the
coating process to eliminate
the weight of coating in the
final results.
• Lumber with various treatments
were equilibrated in
their relative test environments
until less then 1%
weight change was observed
(to allow moisture absorption
equilibration).
• Four each of 5in
x 5in
by
1.5in
blocks of lumber treated
with ACQ, CAB,
SBX, and
CCA were prepared. Three ecoated
carbon steel fasteners
(as prepared above) were
drilled into each wood block.
All fasteners were drilled
until the tip was observed to
break through the backside
of the board. The treated
Parabolic Regression and Actual Data
fasteners were then placed
into the following environments:
Phase 1:
1. Kesternich cabinet at 120ºF
with an RH of 90 ± 3%
Phase 2:
2. Kesternich cabinet at 140ºF
with an RH of 90 ± 3%.
3. Kesternich cabinet at 75ºF
with an RH of 90 ± 3%.
4. Environmental oven at 120ºF
with a relative humidity of 60
± 5%.
5. Ambient conditions in room
at 75ºF and an RH of 30 ± 5%.
• The Phase 1 fasteners were
exposed for 0.07, 0.17, and
0.29 years in condition 1
above to assess a worstcase
environment.
• The Phase 2 fasteners were
exposed for 0.1, 0.17, 0.34,
• In all samples, at the conclusion
of their allotted time, the
wood was split and the fasteners
removed, cleaned, and
weighed.
• The corrosion was removed
from each fastener by gentle
scrubbing and immersion in
a 20 wt % ammonium citrate
solution.
• A secondary corrosion removal
step was accomplished
with a twominute
immersion
in a 100% HCl bath, followed
by gentle scrubbing.
• Complete removal of corrosion
was verified using optical
microscopy.
• The samples were weighed
and the corrosion products
gravi metrically determined by
difference.
• The data from both experimental
phases were recorded,
plotted, and
modeled using
JMP v. 5.0 statistical
analysis
software. Par a bolic
rate functions
were de termined
from
the gravimetric
data for predictive
mo deling.
TEST
RESULTS
Figure 2 il lustrates
the
gravimetric profiles
of the treatments
tested
over time, reflecting
a parabolic
rate mech anism
for the
corrosion observed
in all
treatments stu died
(ACQ, CAB,
and CCA).
Ennis et al. 79
Corrosion of Fasteners
Figure 3 – Extent of corrosion up to 2,528 hours at 140ºF and 90% RH for
uncoated 1022 steel, ecoated
1022 steel, and stainlesssteel
fasteners.
1. Figure 3 illustrates the differences
observed in the various
treatments used in Phase 1
for extent of corrosion with
stainless steel, ecoated
carbon
steel, and uncoated
carbon steel. The stainlesssteel
fasteners exhibited
no corrosion in any of
the lumber treatments
tested, and thus were
eliminated from further
studies. Further, little or
no corrosion was observed
in the untreated or SBXtreated
lumber.
2. Corrosion was observed in
the fasteners emplaced in
CCA,
ACQ,
and CABtreated
lumber.
3. Where corrosion was ob served
(only on samples
ex posed to 90% RF), the
weight loss data from the
ecoated
carbon steel fasteners
fit parabolic rate
models with correlation
coefficients (Rsquared
values) ranging from 0.87
to 0.99 (indicating good fits).
The Arrheniuslike
relationship
was found to be:
y = y0 + kp (t) 0.5 (1)
Where:
y is the oxide mass gain due to
oxidation.
t is time of exposure.
kp is the rate constant, directly
proportional to the diffusivity
of the ionic species, which are
rate controlling.
y0 is a constant.
4. Parabolic rate mechanisms
are commonly
observed for lower
temperature corrosion
kinetics and suggest
an ionspe
cies
di f fus ionl
imi t ed
rate mechanism driven
by temperature
and humidity.
5. The temperature ap pears
to be the key
driver in the extent
of corrosion, though
a sustained presence
of moisture
within the wood is also
required for corrosion to
occur. It appears that the
ab sorbed moisture becomes
the medium (electrolyte) for
electron transfer.
CCA Response With Increasing Time
Figure 4 – Response curves for ecoated
lumber in CCAtreated
lumber
in the various environments tested.
Ennis et al. 80
Proceedings of the RCI 25th International Convention
Figure 5 – Response curves for ecoated
lumber in ACQtreated
lumber in the various
environments tested.
Figure 6 – Response curves for ecoated
lumber in CABtreated
lumber in the various
environments tested.
Proceedings of the RCI 25th International Convention Ennis et al. 81
6. The data additionally
suggested that Fastener Response at 140°F and 90% RH
the relative permeability
of the ecoat
was sufficient to
allow the passage
of moisture to create
the galvanic
circuit.
7. Figures 4 through
6 illustrate the various
responses
with increasing ex posure
time for the
different treatments
tested. Only
those environments
held at 90%
relative humidity
indicated corrosion.
8. Figures 7 and 8,
respectively, illustrate
the response for
those treatments
held at 90% RH.
Fastener Response at 75°F and 90% RH
9. Corrosion was only
observed for those
conditions where
the relative humidity
was held at 90%
RH and at 140º
and 75º respectively.
No corrosion
was observed for
samples held at
120ºF and 60%
RH, or for those
held at 75ºF and
30% RH (Fig ures 9
and 10). The relative
humidity has
to be sustained at
high levels ap proaching
90% in
order for the wood
to retain sufficient
moisture for a galvanic
cell to be
functional, and
thus is a re quire ment
for corrosion to occur. 11. After the tests, the corrosion was observed to
occur in areas where ecoating
was lost in the
10. At typical ambient conditions, the responses initial drilling. Further, there was evidence of
observed for the treated lumbers are comparable corrosion on ecoated
portions of the fasteners
to those observed with CCAtype
treatments. with no evidence of coating loss, suggesting difFigure
7 – Fastener responses for different treatments at 140ºF and 90%
RH.
Figure 8 – Fastener responses for different treatments at 75ºF and 90%
RH.
Ennis et al. 82
Proceedings of the RCI 25th International Convention
Fastener Response at 120°F and 60% RH
Figure 9 – Fastener responses for different treatments at 120ºF and 60%
RH.
Fastener Response at 75°F and 30% RH
Figure 10 – Fastener responses for different treatments at 75ºF and 30%
RH.
fusion of ionic species through the ecoat.
12. The mechanisms for corrosion for CCA lumber
are the same as those for the ACQ and the CAB.
The ACQ and CAB
demonstrate higher rates of
corrosion if sufficient moisture is present. It is
used in this test. Each unit contained one ecoated
sample
and one HDGcoated
sample. Therefore, two fasteners
were in each sample unit for a total of 20 samples units
(wood and fasteners).
suggested that the
lumber needs to
maintain saturation
in order for corrosion
to occur.
13. For conditions typical
of a roof, the typical
ambient temperature
and typical levels
of moisture saturation
required to
generate corrosion
are not problematic.
14. In four years, DuroLast
has seen no
indication that rooftop
conditions are
sufficient to cause
accelerated fastener
corrosion in ACQ or
CAB
treated lumber.
15. For the temperature
and moisture conditions
observed in the
field study, no corrosion
is sues would be
expected.
LSU WOOD
DURABILITY LAB
(WDL) STUDY, T.F.
SHUPE, ET AL.
OBJECTIVES
The objective of this
study was to evaluate the
corrosion effects of ACQ
type D, groundcontact,
treated lumber on 4in
and
5in
hotdipped,
galvanized
(HDG) 4in
metal fasteners,
and two ecoated
metal fasteners, also 4in
and 5in.
The test included
10 fasteners for each metal
tested. The wood samples
were cut from a treated
ACQ ground contact 4in
x
6in
x 8ft
board. A total of
40 metal fasteners were
Proceedings of the RCI 25th International Convention Ennis et al. 83
Figure 11
PROCEDURE
SYPtreated
4 x 6
ACQtype
Dtreated
materials were purchased
locally from
Lowes and milled on a
tablesaw at the WDL
into samples measuring
3 in x 3 in x 6 in.
The test was started
on 04/24/09 and concluded
on 06/22/09.
The test sample units
consisted of two fasteners
imbedded in a
3in
x 3in
x 6in
piece of SYP ACQtreated
4 x 6. Fas teners
were driven
into the sample units
using an electric drill. The fasteners
were spaced at 12 times their respective
diameter within the sample unit.
Each sample unit contained one coated
and one HDG fastener. After 60
days of exposure at 90ºF and 90%
RH, the fasteners were removed from
the wood by splitting the wood with a
wood chisel. The samples were visually
rated and weighed. The samples
were then cleaned with Evapo Rust to
remove corrosion materials, ovendried
in a forcedraft
oven, and
reweighed. Diameter measurements
of the fastener were taken with a digital
caliper to determine the amount
of local rusting.
RESULTS
Fastener weight loss was minimal
for the ecoated
fasteners losing 0.01
grams when exposed to accelerated
conditions inside ACQ type D,
groundcontact,
treated wood. Fas tener
weight loss was greater for 4in
HDG, losing 0.48 grams, and 5in
HDG, losing 0.53 grams when ex posed
to accelerated conditions inside
ACQ type D, groundcontact,
treated
wood. Diameter loss values for the
ecoated
fasteners were unchanged
for the 4in
sample and 0.001 cm for
the 5in
sample. Diameter loss values
for the 4in
HDG was 0.007 cm and
loss for the 5in
HDG was 0.010 cm.
Rusting was found to be very minor
on all fasteners tested.
CONCLUSIONS
1. Weight loss and diameter loss
for the 4in
HDG and 5in
HDG were greater than that
of the ecoated
fasteners
while exposed in a accelerated
condition chamber when
set in ACQ type D, groundcontact,
treated wood.
2. Rusting was very minor on all
fasteners tested, with some
minor spots found on the
heads, shafts, and shanks.
3. Rust was not present on the
HDG fasteners below the
head of the fasteners; however,
most of the coatings were
removed and fixed to the
wood surfaces.
4. There was minor coating loss
on the shanks of the ecoated
sample.
VISUAL TEST
One of the early evaluations conducted
was a straightforward one that
provided the ability to visually evaluate
the corrosion potential of ACQtreated
lumber in contact with metal
fasteners. This test started in March
of 2004.
TEST PROTOCOL
• Epoxycoated
screws were
installed into three 1ftlong
pieces of 2in
ACQtreated
2 x
4s.
• One sample was left as
received, a second sample
was soaked for 24 hours in a
bucket of water simulating
rain on the nailer during construction,
and the third sample
has been soaked in a
bucket of water for 24 hours
the first business day of every
month (64 months), which
represents a very extreme
condition.
• An aluminum term bar was
also installed on each piece
since aluminum is reported
to be very susceptible to corrosion
in contact with ACQ
(see Figure 1).
TEST RESULTS
1. The screws show no evidence
of accelerated corrosion.
There was a very small
amount of corrosion present
in the recess from contact
with the bit during installation.
This would be observed
with any screw that is soaked
in water for 24 hours every
month.
Ennis et al. 84
Proceedings of the RCI 25th International Convention
Figure 12 – Installed instrumentation.
2. No unusual corrosion was
observed on aluminum term
bar.
FIELD STUDIES
TEST OBJECTIVES
The objectives of the field studies
were:
1. Determine how long wood
nailers stay wet if saturated
with water prior to installation.
2. Gather field data in various
climates and measure wood
nailer moisture content.
3. Use the data to develop a
model to predict drying times
in various climate zones.
4. Compare collected data to the
critical temperature/humid ity
levels identified in the laboratory
test procedures that
are required to initiate severe
corrosion of metal.
Figure 13 – Simulated wood nailers installed on
roof deck.
TEST PROCEDURE
To satisfy the objectives of this test
program, the following test protocol
was developed.
Three test sites were chosen for
this experiment. All test sites were
located at SPRI member facilities so
that any problems with the test
equipment could be corrected quickly.
Agawam, MA, was chosen as a test
location representing a cold climate
zone. Jackson, MS, was chosen as a
hot and humid climate zone, and
Grants Pass, OR, was chosen as a
mild and humid climate zone. These
sites were chosen because the climate
conditions present would provide a
variety of temperature and humidity
levels.
Nominal 2in
x 4in
x 2ft
wood
sections were saturated by submerging
them in water for 30 days. After
the submersion period, the samples
were wrapped in plastic wrap to keep
the moisture in place and were
shipped to the test location.
Once at the test location the samples
were unwrapped and instrumented
with temperature and moisturecontent
sensors. Figure 11 is a
schematic representation of the
instrumentation used in this study.
Figure 12 shows the actual test samples
used in the experiment.
Insulation was cut and removed so
that the test samples could be
installed directly on the roof deck (see
Figure 13).
The temperature and moisturecontent
sensors were connected to a
data acquisition system to allow for
continuous monitoring of the information.
The data were remotely
downloaded once per week and maintained
by Oak Ridge National
Laboratory. In addition to monitoring
the instrumentation connected to the
test samples, the interior temperature
and relative humidity near the roof
cut were also monitored.
The initial installation of the saturated
wood samples occurred on
November 13, 2007, in Agawam, MA.
Installation of the test samples at the
Jackson, MS, location on January 15,
Proceedings of the RCI 25th International Convention Ennis et al. 85
Figure 14 – Jackson, MS, average daily temperatures.
Figure 15 – Jackson, MS, average daily RH.
2008, followed. It was determined location on June 5, 2008, and at the TEST RESULTS
that the instrumentation in these iniAgawam,
MA, location on July 24, The average daily temperatures
tial tests was not adequately sensitive 2008. After it was determined that the within the wood nailers were highest
to gather the desired information. instrumentation was working properat
the Jackson, MS, test location. At
Test samples and instrumentation ly, samples were installed at Grants this location, temperatures remained
were reinstalled at the Jackson, MS, Pass on September 24, 2008.
Ennis et al. 86
Proceedings of the RCI 25th International Convention
Figure 16 – Agawam, MA, average daily temperature.
Figure 17 – Agawam, MA, average daily RH.
above 70ºF for the first 100 days of in the wood nailer at this location
exposure (test was initiated June 5, ranged from 85% to 100% at the start
2008). Temperatures ranged from of the test and dropped to a range of
40ºF to 70ºF for the next 205 days of 60% to 70% after 120 days (except for
exposure. The relative humidity withthe
200to
220days
time period). See
Proceedings of the RCI 25th International Convention
Figures 14 and 15 for a summary of
these data.
At the Agawam, MA, location, the
temperature within the wood nailer
ranged from 70ºF to 80ºF for the first
Ennis et al. 87
Figure 18 – Grants Pass, OR, average daily temperatures.
Figure 19 – Grants Pass, OR, average daily RH.
50 days of the test (test started on The relative humidity within the sima
summary of these test data.
July 24, 2008), dropped to a range of ulated wood nailers for this location At the Grants Pass, OR, test site,
50ºF to 70ºF for the next 60 days, and started at 90% to 100% and dropped the test temperatures within the simthen
dropped to a range of 35ºF to to a maximum of 60% after 80 days ulated wood nailers ranged from 30ºF
50ºF for the subsequent 90 days for the remainder of the test period to 60ºF for the duration of the test. At
before beginning to increase again. (310 days). See Figures 16 and 17 for
Ennis et al. 88
Proceedings of the RCI 25th International Convention
Figure 20 – Visual test setup.
this location, the moisture
content sensors in
one of the test samples
malfunctioned; however,
the moisture content
sensors in the duplicate
sample performed well.
The relative humidity at
this location started at
approximately 90% and
dropped to a range of
45% to 55% after 70
days, where it remained
for the duration of the
test. See Figures 18 and
19 for a summary of
these test data.
The maximum temperatures
and relative
humidities were observed at the
Jackson, MS, test site. Previous studies
have indicated that temperature
and humidity are key drivers for the
corrosion process when metal fasteners
are in contact with treated lumber.
Since this is the case, the
Jackson, MS, location would represent
the most likely location for corrosion
to occur.
CONCLUSIONS
1. The relative humidity has to
be sustained at high levels
approaching 90% in order for
the wood to retain sufficient
moisture for a galvanic cell to
be functional and, thus, is a
requirement for corrosion to
occur. This conclusion is
based on exposure of 1022
carbon steel ecoated
fasteners
to wood treated with ACQ,
CAB,
and CCA.
2. Temperature appears to be
the key driver to the extent of
corrosion, though a sustained
presence of moisture within
the wood is also required for
corrosion to occur.
3. The mechanisms of corrosion
for CCA lumber are the same
as that for ACQ and CAB.
The ACQ and CAB
demonstrate
higher rates of corrosion
if sufficient moisture is
present.
4. No measurable corrosion was
noted on stainlesssteel
fasteners
during this study.
5. No measurable corrosion was
noted on fasteners exposed to
SBXtreated
wood.
6. Field studies demonstrated
that the wood nailers dried
from a saturated condition to
a range of 45% to 65% RH
within six months of exposure.
The highest RH occurred
at the Jackson, MS,
test site.
7. Comparing conditions required
for corrosion to occur
in the laboratory test program
with the conditions that
exist in the nailer corrosion of
ecoated
or stainless steel
fasteners will not be an issue.
8. There have been no reports of
excessive fastener corrosion
when installed in treated
wood nailers, supporting conclusion
#7.
RECOMMENDATIONS
1. Use either nontreated or
SBXtreated
wood for the
nailers.
2. If treated wood is used, either
ecoated
steel fasteners or
stainlesssteel
fasteners
should be used.
3. In all cases, a Factory
Mutualcompliant
fastener or
equivalent should be used.
REFERENCES
American Wood Products Associ a
tion (AWPA) Standard E1294.
T. Cushman, “PressureTreated
Wood: The Next Generation,”
pp. 34,
1213,
Journal of
Light Construction, April
2009.
T.R. Shupe, Q. Wu, J. Curole, M.
Voitier, D. Ring, Wood
Durability Lab, Louisiana
Forest Products Development
Center, Report # WDL200906,
School of Renewable
Natural Resources, LSU
Agricultural Center, 2009.
H. Wieland, “Fastener Corrosion
in ACQ and other ‘next generation’
treated lumber,” pp. 12,
produced for RCI under
contract of SFS intec, Inc.,
2004.
Proceedings of the RCI 25th International Convention Ennis et al. 89