European Journal of Wood and Wood Products

, Volume 77, Issue 2, pp 257–269 | Cite as

Solutions to reduce moisture driven backout and improve withdrawal strength of nailplates: experimental investigations

  • Alexander MaineyEmail author
  • Benoit P. Gilbert
  • Henri Bailleres
  • Shanmuganathan Gunalan
  • Matthew Smith


Timber trusses, typically manufactured from timber members connected by nailplates, are widely used in the domestic housing market. Their use is however limited to indoor environments. The exposure of timber trusses to environments where the timber experiences high amounts of moisture content (MC) variations causes the nailplates to be driven out from the surface of the timber, a phenomenon commonly referred to as “backout”. As part of a collaborative project between the industry, Griffith University and Queensland Department of Agriculture and Fisheries (DAF), this paper aims at investigating solutions to both prevent backout of the nailplates and increase their withdrawal resistance under large MC variations. The nailplate teeth were redesigned following (1) a mechanical approach consisting of redesigning the tooth profile and allowing the nails to resist the withdrawal force by both friction and mechanical action and (2) the application of an adhesive to a redesigned tooth profile, allowing the adhesive to penetrate the timber with the nail. The efficiency of the new designs was experimentally assessed using single teeth (representative of nailplate teeth) with respect (1) to their ability to resist backout resulting from accelerated MC cycles and (2) their quasi-static withdrawal resistance after increasing numbers of moisture cycles. Results showed that the proposed mechanical designs reduced the backout by up to 50% when compared to currently used tooth designs. The application of an adhesive prevented moisture driven backout. The newly investigated tooth designs resulted in higher withdrawal strengths to currently used nails. It was identified that subjecting the nails to only one moisture cycle reduced the withdrawal resistance of currently used and glued teeth by up to 60% while the withdrawal resistance of the proposed mechanical designs was not affected by the number of cycles.



The authors express their gratitude to Multinail Australia for providing the required support and material for the project. The main author also acknowledges the funding provided by the Australian Government Research Training Program Scholarship.

Compliance with ethical standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.


  1. Allday A (2017) Wooden structural component manufacturing in Australia. IBISWolrd IBISWorld Industry Report C1492Google Scholar
  2. ANSI/TPI 1-1995: National design standard for metal plate connected wood truss construction. American National Standards Institute (1995), New York, New YorkGoogle Scholar
  3. Atkins WB (1962) Connector plate. United States of America. US3016586AGoogle Scholar
  4. Bylund D (2017) Enabling prefabricated timber building systems for class 2 to 9 buildings. F. a. F. D. Australian Government Department of Agriculture Project number: PNA324-1314Google Scholar
  5. Foschi RO (1977) Analysis of wood diaphragms and trusses. Part I: diaphragms. Can J Civ Eng 4(3):345–352CrossRefGoogle Scholar
  6. Gebremedhin GK, Crovella LP (1991) Load distribution in metal plate connectors of tension joints in wood trusses. Trans ASAE 34(1):281CrossRefGoogle Scholar
  7. Groom LH (1994) Effect of moisture cycling on truss-plate joint behavior. For Prod J 44(1):21Google Scholar
  8. Groom L (1995) Effect of moisture cycling on mechanical response of metal-plate connector joints with and without an adhesive interface. New Orleans, Louisiana, United States Department of Agriculture—Forest Service—Research Paper so-291—September 1995Google Scholar
  9. Guo W, Song S, Jiang Z et al (2014) Effect of metal-plate connector on tension properties of metal-plate connected dahurian larch lumber joints. J Mater Sci Res 3(3):40–47Google Scholar
  10. Houška M, Koc P (2000) Sorptive stress estimation: an important key to the mechano-sorptive effect in wood. Mech Time-Depend Mater 4(1):81–98CrossRefGoogle Scholar
  11. Mainey AJ, Gilbert BP, Baillieres H, Gunalan S, Smith M (2016) Mechanical and artificial improvement of nailplate connected timber truss joints. In: Proceedings of the 10th World Conference on Timber Engineering WCTE2016. Vienna, AustriaGoogle Scholar
  12. McAlister RH (1990) Tensile loading characteristics of truss plate joints after weathering and accelerated aging [1990]. For Prod J 40(2):9–15Google Scholar
  13. Melton T (2000) Failures of in-service mpc parallel-chord wood floor truss components reveal deficiencies in ansi/tpi standards. A. E. Inc., AustinGoogle Scholar
  14. O’Neill W, Gabzdyl JT (2000) New developments in laser-assisted oxygen cutting. Opt Lasers Eng 34:355CrossRefGoogle Scholar
  15. Paevere P, Nguyen MH, Syme M, Leicester RH (2008) Nailplate Backout—is it a problem in plated timber trusses. In: Proceedings of the 10th World Conference on Timber Engineering WCTE2008, At Miyazaki, JapanGoogle Scholar
  16. Paevere P, Nguyen M, Syme M, Leicester R, Ho K (2009) Mechano-sorptive nailplate backout in nailplated timber trusses. F. W. P. A. Limited, AustraliaGoogle Scholar
  17. Regan PJ, Woeste FE (2002) Withdrawal strength of punched metal tooth plates in red oak end grain. (Wood Engineering). For Prod J 52:82+Google Scholar
  18. Smith GC et al (1988) Wood joint connector plate. United States of America. US4734003Google Scholar
  19. Smulski S (1993) Case study: flat truss failure. J Light Constr 38:39Google Scholar
  20. Standards Australia (2001) AS1649-2001 Timber—methods of test for mechanical fasteners and connectors—basic working loads and characteristic strengths. Sydney, Australia, Standards AustraliaGoogle Scholar
  21. Standards Australia (2006) AS/NZS 1748:2006 Timber—mechanically stress-graded for structural purposes. Sydney, Australia, Standards AustraliaGoogle Scholar
  22. Standards Australia (2012) AS1080.1-2012 Timber—methods of test—moisture content. Sydney, Australia, Standards Australia & Standards New ZealandGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.School of Engineering and Built EnvironmentGriffith UniversitySouthportAustralia
  2. 2.Department of Agriculture and FisheriesQueensland GovernmentSalisburyAustralia
  3. 3.Multinail AustraliaYatalaAustralia

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