Wood subfloors exposed to saltwater

[Forensic74]

Does anyone have any good rules of thumb or know of any publications discussing wood subfloors that are exposed to saltwater? At what point do you call the floors structurally compromised and have to be replaced? APA published a fairly general article that discusses exposure to water, but I'm thinking saltwater may pose additional issues.

 

[SlideRuleEra]

Saltwater should not damge the wood itself any more than freshwater. However, after the wood has dried the salt is left behind. The salt can and will have a devastating effect on plain steel fasteners that were used. The first evidence of damage will probably be rust staining on the wood above each plain steel fasterner. Depending on factors such as exposure time to saltwater, the water's salt content, how often the subfloor is exposed to water, etc. the fasteners can deteriorate completely. This could take a few years.

If the fasteners were galavanized the chance of staining and worse problems is minimized. Of course, stainless steel fastners would be best.

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[MiketheEngineer]

Avoid it at all costs!!

 

[dhengr]

I think Mike meant to say ‘avoid it at all coasts!!’ And, SlideRule hit the nail on the head.

 

[wannabeSE]

From somewhere in the back of my memory, I remember that salt is hygroscopic. So once the saltwater has dried, the salt reamains and may continue to attract moisture from the air leaving the wood damp.

 

[MiketheEngineer]

The ONLY place you should see saltwater is in an ocean!!

 

[Forensic74]

I agree, unfortunately this thing called a hurricane raises the ocean. There seems to be a vacuum of research or publications on this. Sliderule, your comment regarding fasteners is interesting, and opens a can of worms because you then have to say that all the fasteners that connect the sills to the studs, the exterior sheathing to the studs, etc are trashed. So are you saying that any house you've looked at that was subjected to storm surge is basically totaled, has to be bulldozed and rebuilt? Thats what we're talking if all fasteners that were exposed to saltwater need to be replaced.

Is there any procedure of washing the salt out of the wood prior to drying it?

 

[SlideRuleEra]

MainMan10 - If the house was built with plain steel fasteners and submerged in salt water (typically the hurricane surge) I would be reluctant to say that it has a useful service live of more than, say, 10 years. WannabeeSE is exactly right about the salt continuing attract moisture. Since coastal areas often have high hummidity this helps keep the corrosion going.

In some coastal regions galvanized fasteners have been common use for about 50 to 60 years. Galvanized fasteners (especially the hot-dipped type) can with stand salt water exposure, and its consequences, for quite a while; a few decades.

As for a way to take the salt out... short of submerging the house in fresh water for an extended time (not at all practical), I don't know of a way to do this.

My advice would be to spend the time to see IF the fasteners are plain steel. If they are, the long-tem future of the structure is not good.

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