11/21/2016 | 01:47pm EST
The manufacturers of PT wood and metal connectors and fasteners have been dancing around the corrosion issue ever since. And while it’s common practice to use hot-dipped galvanized (HDG) hardware with PT lumber, I think that ALL metal fasteners or connectors in contact with high-concentration copper PT lumber in environments that are subject to water or high levels of moisture should be stainless steel. Here’s why.BRANZ Study
The most common ASTM and AWPA testing methods for fastener corrosion involve the use of test chambers with high temperatures, high humidity, salt compounds, and other factors in order to simulate long-term exposure over a short period of time. This is called accelerated testing, and while useful for quality-control purposes, salt-spray test results don’t really predict how well materials and coatings will resist corrosion in the real world. Meanwhile, there has been little multi-year testing done in real-life weather-exposure situations.The most extensive non-accelerated study seems to be one conducted by BRANZ (Building Research – New Zealand), a New Zealand nonprofit government-funded construction and building-materials research group. In 2007, BRANZ started a three-year study designed to test real-world behavior of mild steel, hot-dipped galvanized (G185) steel, and stainless steel nails, screws, and flashings in untreated wood and in CCA-, CA-, and ACQ-treated lumber in coastal (severe) and mild/non-coastal environments. (…)
via ASHI American Society of Home Inspectors : BRANZ Study Focuses on Fastener Corrosion.