Aluminum and wood/treated wood: Corrision

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Aluminum and wood/treated wood: Corrision

Postby kevindford » Thu Dec 21, 2017 4:44 pm

Hey all- I can't find a complete source about this topic- any experts help enlighten me?

I have a Northern Tool 5x8 non-folding aluminum trailer, and intend to deck with treated 5/8" ply. I haven't decided on the treatment.

I've read on boat building forums that aluminum will corrode when in close contact with treated wood- is this so and if so what is the solution?

Thank you!
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Re: Aluminum and wood/treated wood: Corrision

Postby featherliteCT1 » Thu Dec 21, 2017 6:42 pm

I covered some 6 x 6 treated lumber posts with aluminum fabricated from aluminum trim coil stock. Within one year, the chemicals from the treated lumber ate holes through the aluminum. Not a good idea.
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Re: Aluminum and wood/treated wood: Corrision

Postby kevindford » Thu Dec 21, 2017 8:27 pm

featherliteCT1 wrote:I covered some 6 x 6 treated lumber posts with aluminum fabricated from aluminum trim coil stock. Within one year, the chemicals from the treated lumber ate holes through the aluminum. Not a good idea.


Was that aluminum galvanized? Any idea of the solution?

Thx-
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Re: Aluminum and wood/treated wood: Corrision

Postby Tigris99 » Fri Dec 22, 2017 12:14 am

Do NOT use treated lumber near aluminum, ever. Only safe hardware is deck hardware.

Aluminum, even anodized will get destroyed by treated lumber.

Better not to use pre-treated lumber for these anyway. The chemicals that come out of treated wood as it seasons are quite toxic.

Much better off with standard exterior ply and rubberized undercoating. Treated ply will still go to crap if not protected, just lasts longer. Rubberized undercoating as a heavy coat on the bottom of regular ply and then good exterior paint inside till be safer and last just as long if not longer.

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Re: Aluminum and wood/treated wood: Corrision

Postby Tigris99 » Fri Dec 22, 2017 12:14 am

Do NOT use treated lumber near aluminum, ever. Only safe hardware is deck hardware.

Aluminum, even anodized will get destroyed by treated lumber.

Better not to use pre-treated lumber for these anyway. The chemicals that come out of treated wood as it seasons are quite toxic.

Much better off with standard exterior ply and rubberized undercoating. Treated ply will still go to crap if not protected, just lasts longer. Rubberized undercoating as a heavy coat on the bottom of regular ply and then good exterior paint inside till be safer and last just as long if not longer.

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Re: Aluminum and wood/treated wood: Corrision

Postby swoody126 » Fri Dec 22, 2017 8:34 am

DECK HARDWARE (unless stainless steel) is ONLY good for WOOD > WOOD applications

the protective coating gets abraded when being screwed/bolted thru a metal component

the abrasion reveals the bare metal of the fastener which negates any benefits expected

the SALTS used for preservation of the wood are hard on common metals and can cause infections/reactions when they get under your skin

i'm not saying to knot use the stuff JUST BE INFORMED

sw
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Re: Aluminum and wood/treated wood: Corrision

Postby jmanscotch » Mon Apr 02, 2018 9:31 pm

On the advice of others, just avoid it.

That said, well coated aluminum will not react to the treated lumber so long as the coating remains intact fully (doable, but not easily). Just FYI as something to consider along the way.
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Re: Aluminum and wood/treated wood: Corrision

Postby Andrew Herrick » Thu Apr 05, 2018 9:42 pm

Much easier to change your wood choice rather than mess with aluminum coatings or chemical barriers.

As has been pointed out, the standard floor is a 1/2-inch to 3/4-inch exterior grade (usually ACX or BCX) plywood with an undercoating. Rubberized (elastomeric) coatings are best. Non-rubberized coatings are more brittle and will crack easier.

Other alternatives include aluminum sheet skid plates, AdvanTech exterior-grade OSB, mobile home belly wrap, etc. They ALL work. Just pick whichever one is easiest for you to get locally.

IMHO, there's not a good reason to go with treated plywood, which is usually CDX sheathing stuff, and warps like crazy, and won't hold fasteners as well as BCX or CDX plywood.
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Re: Aluminum and wood/treated wood: Corrision

Postby tony.latham » Thu Apr 05, 2018 10:01 pm

Andrew Herrick wrote:Much easier to change your wood choice rather than mess with aluminum coatings or chemical barriers.

As has been pointed out, the standard floor is a 1/2-inch to 3/4-inch exterior grade (usually ACX or BCX) plywood with an undercoating. Rubberized (elastomeric) coatings are best. Non-rubberized coatings are more brittle and will crack easier.

Other alternatives include aluminum sheet skid plates, AdvanTech exterior-grade OSB, mobile home belly wrap, etc. They ALL work. Just pick whichever one is easiest for you to get locally.

IMHO, there's not a good reason to go with treated plywood, which is usually CDX sheathing stuff, and warps like crazy, and won't hold fasteners as well as BCX or CDX plywood.


What he said... :thumbsup:

Tony
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