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Draft Final Report for Project Entitled:Corrosion of Residential FastenersPerformance Period: 10/7/2016 – 6/30/2017Submitted onJune 1, 2017Presented to theFlorida Building CommissionState of Florida Department of Business and Professional RegulationbyKurtis R. Gurley, Ph.D., kgurl@ce.ufl.edu, (352) 294-7795Engineering School for Sustainable Infrastructure & Environment

Table of Contentsof Contents1. Disclaimer . 12. Issues Being Addressed . 13. Applicable Sections of the Code and Related Documents . 14. Review of 2015 – 2016 Testing . 15. Statement of Work for 2016 - 2017 . 25.1. Work completed in this performance period . 36. Project Description of 2016 – 2017 testing . 36.1. Test protocol (TAS 114 Appendix E) . 36.2. Procurement of specimens tested . 36.3. Test-1 description and conditioning (150 samples) . 36.4. Test-2 description and conditioning (160 samples) . 46.5. Corrosion scale – performance metric. 57. Results of Corrosion Scoring . 67.1. Test-1 results . 67.1.1. Test-1 discussion . 87.2. Test-2 results . 97.2.1. Test-2 discussion .118. Comparison of Hot Dipped and Electrogalvanized Nail Corrosion Resistance.119. Conclusions .1210. Appendix A: Test-1 Corrosion results (photos for sample of each specimen type) .1311. Appendix B: Test-2 Corrosion results (photos for sample of each specimen type) .21

1. DisclaimerThis report presents the findings of research performed by the University of Florida. Anyopinions, findings, and conclusions or recommendations expressed in this report are those ofthe authors and do not necessarily reflect the views of the sponsors, partners and contributors.The appropriate Technical Advisory Committees of the Florida Building Commission will providea final disposition on the implications for the Florida Building Code.2. Issues Being Addressed Anecdotal information indicates that corrosion of fasteners has been observed across arange of installationsThe problem is more serious in coastal environments due to presence of chloride ionsIncreased manufacturing of these products outside the United State may be contributingto the problemThe 2015-2016 corrosion study focused ono Electrogalvanized roofing fasteners conforming to ASTM A641 or TAS 114Appendix E standardso Hot dipped fastenerso Roof tile fastenerso Screen enclosure fastenersThe 2016-2016 corrosion study identified performance issues that warrant further testing3. Applicable Sections of the Code and Related Documents 1622.1.2, Florida Building Code—Building1506.4 – 1506.7, Florida Building Code—Building1517.5.1 – 1517.5.2, Florida Building Code—BuildingGuide to Aluminum Construction in High Wind AreasTAS 114 Appendix EASTM A90ASTM A641ASTM A153ASTM B117-11ASTM G85-114. Review of 2015 – 2016 TestingThe 2015 – 2016 experimental study (phase 3) continued the testing roof system fasteners in acorrosion chamber, applying the TAS 114 Appendix E protocol and applying the customizedcorrosion scoring scale created for phase 2. In phase 3, the emphasis was on testing fastenersthat are ASTM A641 compliant (prescriptive) or Miami Dade County approved (performancebased TAS 114 Appendix E). Electrogalvanized, electroplated, mechanically galvanized, hotdipped, and stainless steel fasteners were included in the test matrix. Roofing, deck/patio,screen enclosure, and tile screw fasteners were also included. The following summary offindings was reported in the Final Report issued on June 21, 2016:1

It is assumed that Miami-Dade approved EG fasteners had been certified as TAS 114Appendix E compliant. However, the results did not reveal a single EG sample thatpassed that standard’s criterion of 5% surface corrosion. Each of the 30 such fastenersamples tested had a score of at least 3 (partial light surface corrosion) on both the headand shaft, and most samples displayed significant heavy corrosion. Each of the three EGspecimen types marked as Miami-Dade approved only referenced ASTM A641, not TAS114 Appendix E.The hot dipped, mechanically galvanized and stainless steel ceramic coated specimensdemonstrated little or no corrosion.The corrosion resistance of hot dipped specimens does not appear to be influenced(damaged) by installation. However, due to a relatively small sample size and theinclusion of only two specimen types, this conclusion is indicative rather than definitive.Testing on ceramic coated stainless steel screen enclosure fasteners revealed somedegradation to the ceramic coating on the stainless steel specimens. The exposedstainless steel did not exhibit significant corrosion. However, unlike metal reactions dueto loss of the coating barrier were not evaluated since these specimens were tested outof the box and not in an installed configuration.5. Statement of Work for 2016 - 2017The current 2016 – 2017 experimental study (phase 4) continues the testing of residentialfasteners in a corrosion chamber, applying the TAS 114 Appendix E protocol and applying thecustomized corrosion scoring scale created for phase 2. The testing plan is described asfollows: The 2015 - 2016 study revealed that the ceramic coating on stainless steel masonryscrews (commonly used for screen enclosures) peeled during the corrosion testing. Thismay create issues with unlike metal reactions when these fasteners are used inaluminum enclosures. The testing will install ceramic coated SS screws in aluminumprior to corrosion testing in order to investigate the implications of loss of coating withrespect to corrosion at the unlike metal interface.Additional tile fastener testing will be conducted to add multiple commonly used productsto the limited results from the 2015-2016 study.Hot dipped roofing fasteners performed much better than electrogalvanized fasteners inthe 2015-2016 study. Fasteners conforming to the ASTM A153 hot dipped standard andthe ASTM A641 minimum coating standard will be tested for relative performance.HVAC and metal panel clips and fasteners will be included in the 2016-2017 test matrixThe test protocol includes the following: Apply TAS 114 Appendix E testing (Section 2.6.1) to evaluate the degree of corrosionresistanceTesting will be conducted on both new and installed fasteners to determine the influenceof installation on corrosion resistanceTesting will include multiple samples of each specimen configuration2

5.1. Work completed in this performance periodThe performance period was sufficient to complete the majority, but not all of the fastenertypes listed in the statement of work. Testing was completed on Ceramic coated stainless steel masonry screws Roof tile screws Hot dipped nailsHVAC and metal panel clips and fasteners were not included in the test matrix due to timerestrictions attributable to: a) the use of 500 cycle (1000 hour) sequences for all completedtesting, b) factory required maintenance and upgrades to the test apparatus delayedtransitioning between test sequences.This report presents the results of testing completed on 310 specimens. 150 were testedsimultaneously in test-1, 160 were tested simultaneously in test-2. The results and analysisof test-1 were documented in the interim report issued on February 15, 2017, and will berepeated herein as well for completeness of this document. The results and analysis of test2 are documented herein for the first time.6. Project Description of 2016 – 2017 testing6.1. Test protocol (TAS 114 Appendix E)The test protocol followed TAS 114 Appendix E, which calls for compliance with ASTM G85Annex A5. The corrosion testing apparatus was factory programmed to follow the ASTM G85Annex A5 protocol. The acetic acid-salt spray (fog) test was conducted for 500 cycles (test-1and test-2), where one cycle consists of one hour of fog exposure and one hour of dry-off. Eachsequence was run without interruption over a 42 day period. The salt solution composition,chamber temperature, and water purity were monitored to conform to requirements. There is noconversion of this protocol to an equivalent time of in-field exposure to real conditions.6.2. Procurement of specimens testedAll test samples were procured off the shelf from Florida suppliers.6.3. Test-1 description and conditioning (150 samples)Test-1 includes 10 samples from each of 15 groups. These 15 groups include sheet metal andmasonry screws commonly used for screen enclosures, as well as roofing tile screws. Table 1summarizes the specimens in test-1. Groups 1 – 10 are masonry, SDS and SMS ceramiccoated stainless steel screen enclosure fasteners. Groups 11 – 13 are mechanically galvanizedand electroplated tile screws. Groups 14 and 15 are nylon capped ceramic coated casehardened steel masonry and SDS fasteners. Each of the 15 groups included 10 samples. Allsamples were tested for 1000 hours (500 cycles).3

Table 1: test-1: 15 specimen types, 10 samples each5 samples out-of-the-box, 5 samples installed in substrateStatus: completed 1000 hours (500 cycles)Product typeUseCertificationCoatingHex 3/8 x 5 304 Stainless whiteMasonryCeramic2Hex 3/8 x 7 304 Stainless whiteMasonry3Hex 1/4 x 3 ¼ 304 Stainless silverMasonry4Hex 1/4 x 2 ¼ 304 Stainless silverMasonry5Hex 1/4 10 x 2 SMS 316 Stainless bronze6Hex 1/4 12 x ¾ SDS 316 Stainless white7Hex 5/16 14 x 1 SDS 316 Stainless bronze8Hex 3/8 14 x 1 SDS 316 Stainless bronze9Hex 5/16 12 x 2 SDS 316 Stainless bronze10Hex 1/4 10 x 2 SDS Stainless white11#8 2 ½ mechanically galvanizedASTM B695 Class 55 2006 IRC Compliant#8 2 ½ tile screw heavy zinc electroplated#8 2 ½ mechanically galvanizedASTM B695 Class 55 2006 IRC CompliantHex 1/4 x 3 ¼ case hardened carbon steel blueNylon cap applied post-installHex 5/16 12 x 1 SDS case hardened carbon steelred, Nylon creenenclosureScreenenclosureScreenenclosureTile ovedMDCApprovedIRCTile screwTile icMGThe purpose of test-1 was to provide comparative corrosion performance of samples tested outof-the-box against samples installed into appropriate substrate prior to testing.Five samples from each of Groups 1 – 10, 14 and 15 were installed into aluminum screenenclosure stock prior to testing. The remaining five samples from each of Groups 1 – 10, 14 and15 were tested out-of-the-box.Five samples from each of Groups 11 – 13 were installed into roofing tiles and removed prior totesting. The remaining five samples from each of Groups 11 – 13 were tested out-of-the-box.6.4. Test-2 description and conditioning (160 samples)Test-2 includes 20 samples from each of 8 groups of hot dipped galvanized nails. Differentgroupings separate manufacturers and/or suppliers. Smooth and ring shank samples areincluded, as well as coil and hand-driven samples. Table 2 summarizes the specimens in test-2.4