Re: OT: Working in the rain and galvanic reaction
cooper suter
>Jury's still out on the proper level of corrosion protection required for use w/the new treated (ACQ).
The big issues w/accelerated corrosion seem to be the levels of copper, the carrying agents used to get it into the wood, and how wet the installed environment is.
The new treated has something like 75% copper versus the old (CCA) which had a percentage in the teens.
Went to a training seminar put on by Simpson Strong-Tie.
Until an industry standard level and method of treating evolves, Simpson is only recommending stainless or their "Z-Max" connectors and fasteners be used, especially in wet environments.
(Yes, I asked, they claim they don't make any more profit on these.)
They did have some examples of amazingly fast corrosion w/the new treated and their basic level of galvanized connector.
Decks along the water in Cleveland where the zinc was entirely gone and the steel actively rusting in one year; doesn't bode well for the life span of the hangers load carrying capacity.
An overlooked but big issue is anchor bolts for sills and ledgers, better throw out all the old black bolts, only galvenized from here on out w/treated.
The basic ranking of fastener protection from lowest to highest is; electro-galvanized, hot dipped, cold tumbled, stainless.
Even before the new treated, the basic electro-galvanized gun nails were a poor performer for deck work, they just don't have enough zinc on them to perform in that tough of a corrosion environment, and once the zinc is gone, their smaller diameter leaves less steel to rust through before failure.
I wouldn't go tearing anything out, but keep an eye out for rust stains in the framing; could be an indicator of a future STRUCTURAL problem.
Coop