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Fastener Corrosion in salt-water soaked wood

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This is more of a wood science/chemical/metallurgical engineering
question...

A contractor I know is helping recovery from Katrina.  This contractor
reports that the "official" relief people are mostly concerned with mold
issues when assessing water damage.  He called from Ocean Springs,
Mississippi, asking about the practice of replacing the drywall above the
high-water mark as being adequate rehabilitation of homes that were
inundated with SALT water.  At first he was concerned about the sill anchors
corroding, but then realized that all the sheathing nailing, nails that hold
brick ties if the house has brick veneer, stud nailing, etc. could very well
turn into pockets of rust after a few months or years.

It seems that there could be enough salt absorbed by the wood to continue
corroding fasteners for a long time.  Moisture in the air is enough to keep
the electrolysis going if there is a continuing supply of chloride ions.
But would chloride ions diffuse through the wood to keep up this supply?

I suggested that nailing new shear panels onto the interior face of walls,
using stainless steel nails, and also using stainless steel drop-in anchors
for the mudsills could address this. Expensive, yes, but not nearly as much
as tearing down and rebuilding....   But this would not take care of brick
ties on the outside face of exterior walls, or other inaccessible framing
connections.

In bone-dry California, I might not worry so much about ongoing corrosion.
What do you engineers in more humid regions think about the potential for
eventual fastener failure?  Unfortunately, the corrosion issue may be no
worse than what will happen with standard steel fasteners used with newer
preservative treatments..... (see www.shearwalls.com/treated_wood.html ).

Is flooding with ocean water a death sentence for a wood-framed building?

Thor

www.shearwalls.com


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