A question often asked of us at Anzor is: are Stainless Steel Fasteners o.k with treated timber?

Stainless Steel Fasteners recommended with treated timber


Well the research says not only is it o.k – but it is preferred! Our neighbours over the Tasman in New Zealand have had regulations for some time requiring significant Stainless Steel Fastener use in their coastal construction.   As a result,  the N.Z Ministry of Business, Innovation and Employment (aka Building & Housing) in conjunction with independent research body BRANZ NZ conducted significant testing to find out what would be the most suitable metal fasteners to use with various timber treatments.

The BRANZ report on which fastener material to use in treated timber is very clear:


“BRANZ is currently recommending that for both 15- and 50-year situations where CuAz- and ACQ-treated timbers are used, the fastener material of choice, including nails and screws, should be either: 304/316 grades of stainless steel, or durable equivalents, such as silicon bronze”


Timber treatments such as CCA (Copper Chrome Arsenate ) and ACQ (Alkaline Copper Quaternary) are often used in Australia (see Timber Treatment types in Australia).

With the N.Z Ministry of Business, Innovation and Employment (Building & Housing) going even further:


“In the past there have been timber fastener durability concerns with the use of new high copper treatment options as an alternative to the traditionally used CCA treatment (refer to Build magazine February/March 2007). In that article it was recommended to use stainless steel fasteners or durable equivalents such as silicon bronze, when using these new treatments in timber exposed to the weather.

This led to the Department co-sponsoring further research. BRANZ is now publishing details of this three-year study confirming that significant corrosion rates are being experienced by both mild steel and galvanised nails and screws used as fasteners in Copper Azole (CuAz) or alkaline copper quaternary (ACQ) treated timber (refer to Build article August/September 2009).

We recommend the use of 304/316 grades of stainless steel or durable equivalents such as silicon bronze for all timber fasteners, including nail plates, bolts and nails, for all CuAz or ACQ treated timber exposed to the weather.  The research confirms the corrosion concerns that initiated the study. The Department’s recommendation endorses that made by BRANZ in the Build February/March 2007 edition and confirmed in the recent Build publication.”


For a full range of Stainless Steel Construction Fasteners see Anzor – for Stainless Steel NailsStainless Steel Bolts, Stainless Steel Screwscall, email or come visit us in Brisbane to help.




NB: This information is provided as a guide only and Anzor does not accept liability for the application of this information. For advice about stainless steel contact the Australian Stainless Steel Development Association (ASSDA)

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