Joist hangers & corrosion

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Author Message Richard HIrd (Unregistered Guest) Unregistered guest Posted on Monday, March 25, 2013 - 09:20 pm:    Have 30 year old exterior deck where good old midwest salt is rusting away the original galvanized joist hangers. Could go to new stainless steel, but thought I should ask if there are any other neat ideas Ralph Liebing, RA, CSI, CDT Senior Member Username: rliebing Post Number: 1380 Registered: 02-2003 Posted on Tuesday, March 26, 2013 - 10:35 am:    If you've gotten 30 years out of galvanized, why not just use galvanized connectors [for another 30 life at which point the deck may want to disappear]? If upgrading or replacing good portion of deck then stainless may be your answer. J. Peter Jordan Senior Member Username: jpjordan Post Number: 547 Registered: 05-2004 Posted on Tuesday, March 26, 2013 - 11:28 am:    Am doing a project in Galveston with wood framing. Simpson recommends Type 316 stainless steel and has information on their website as to why they do this. But we are talking about an environment where galvanized steel with a damaged coating will rust away in 5 to 10 years. You situation may be different. Jeffrey Wilson CSI CCS Senior Member Username: wilsonconsulting Post Number: 96 Registered: 03-2006 Posted on Tuesday, March 26, 2013 - 11:53 am:    Another option might be so-called "triple-galvanized" (G-180) framing anchors if they're still available. As I recall, these were first offered in response to rapid deterioration of G-60 galv anchors used with new non-toxic formulations of preservative-treated lumber. These would presumably also have improved resistant to salts. Sheldon Wolfe Senior Member Username: sheldon_wolfe Post Number: 632 Registered: 01-2003 Posted on Tuesday, March 26, 2013 - 03:53 pm:    If you are using preservative treated wood, the joist hangers that lasted thirty years will probably last only three. Richard Hird (Unregistered Guest) Unregistered guest Posted on Tuesday, March 26, 2013 - 09:44 pm:    Decking is cedar plank, I have no idea what the structural frame is. I see no problem with the frame. Same problem as Corten, the hangers are intact, but their rust stains the pavers below. Sheldon, curious about your comment. Are you saying the new treatment systems are that bad! We are not replacing the framing now, but may have to some day. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 546 Registered: 10-2007 Posted on Tuesday, March 26, 2013 - 11:29 pm:    Some of the chemicals used to prevent deterioration of wood will when in contact with moisture cause metals to corrode at a higher rate than if the wood was not treated. Simpson provides a lot of information on this in their catalog. If you are using stainless steel joist hangers it would also make sense to use stainless steel nails. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1490 Registered: 03-2002 Posted on Wednesday, March 27, 2013 - 03:09 pm:    The most common of the new wood treatments contain higher levels of copper, which react with the zinc in galvanized fasteners when in contact with water. This is especially true for exposed products such as joist hangers for an outdoor deck. It's generally not a concern for dry locations, such as indoors. Some species of wood are naturally more decay-resistant than others, specifically Douglas fir, and southern yellow pine, according the the US Forest Service. Using these may be acceptable in lieu of treated wood depending on the service conditions. Otherwise, separate galvanized metal from treated wood with a slip sheet or similar method. Sheldon Wolfe Senior Member Username: sheldon_wolfe Post Number: 634 Registered: 01-2003 Posted on Wednesday, March 27, 2013 - 04:25 pm:    With the exception of redwood, my experience with naturally decay-resistant wood has been unsatisfactory. Those woods do last longer than others, but not long enough. I spent the bucks for cedar for one of my decks, and ended up replacing it after less than ten years. My original redwood deck, which I built thirty years ago, is now failing. The surface boards, nominal 3/4 inch, are rotting at the ends, where they rest on joists. The structure is all CCA treated wood; it's doing great.