So who's right?? Treated plywood is safe??

D

Don Schwader

Member
Guy's I was at Menards a lumber yard here in N.E. Wisc. and was ready to order 2 4X8 sheets of 1/2 MDO. The guy behind the counter asked me what I was using it for? I told him to replace the floor in a boat, he asked me why I didnt use treated plywood? I told him the treated plywood would eat away the alum.. He told me that the new treated plywood is safe for all soft metal inc. alum.. Now I am really confused are you guys sure about treated plywood eating up alum.? Why would this guy tell me this, after all he could have sold me the MDO at over twice the price as the treated. I didn't get the MDO or the treated, as now I'm totally confused, does anyone here know the truth on the new treated plywood?
 
Guy's I was at Menards a lumber yard here in N.E. Wisc. and was ready to order 2 4X8 sheets of 1/2 MDO. The guy behind the counter asked me what I was using it for? I told him to replace the floor in a boat, he asked me why I didnt use treated plywood? I told him the treated plywood would eat away the alum.. He told me that the new treated plywood is safe for all soft metal inc. alum.. Now I am really confused are you guys sure about treated plywood eating up alum.? Why would this guy tell me this, after all he could have sold me the MDO at over twice the price as the treated. I didn't get the MDO or the treated, as now I'm totally confused, does anyone here know the truth on the new treated plywood?
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ACQ is not compatable with aluminum.
 
Hey Don,
Do some research.....try google.
Regardless of how you look at it........the material infused into the plywood is a poison, designed to kill mold when wet........in contact with the ground. It is activated when wet.

I've never been that much impressed with anybody at Menards, Depot or Lowes when it comes to matters like this. I have always relied on fellas at privately owned yards like Locke Lumber (around here) and Northern Cashway Lumber (and we know where that is). ;) Being in the boat building industry or hobby......many of us have had some experience. But then, that's just MHO. ;)
When it boils down to it.....the decision is still....yours.

Lou
 
I relieve you of the confusion. Get the MDO. The treated plywood whether or not the chemicals react with the aluminum or not is not what you want in you boat. Ask your self this. Why do they treat plywood. To Kill bugs and mold......Any thing that will kill bugs and mold will kill you.....You are going to saw it, breath the dust. touch it with bare hands. Ask you self is it worth the risk for you, your kids, your dog. Ok I am off my box..
 
I agree with Lou, never trust the people at Menard, Home Depot or Lowes. They generally know where the material is in the yard, but after that, well, I wouldn't follow any advice.

If your in Green Bay, go over to Stock lumber and ask for Marine grade Doug Fir, not the lightest stuff, but should work.
 
How long had the old plywood been in there before it rotted? Weeks? Months? Probably years or even decades. Just use untreated plywood. It will likely last longer than you will want the boat anyway.
 
Andrew, My lab was just 6mo. old and I remember you had your lab at the club and you showed me the dummy launcher you used to train your lab. You had your little boy with you, I only shot for 1yr. on the team. Anyway thanks for the advice on my question!!
 
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Here's a update, two clerks at Menards two different opinions!! I went back and asked a different clerk and here's what he told me DO NOT USE TREATED PLYWOOD!! He said when they changed the treated to the new AC-II or AC-TWO it will eat alum. the only way it might be safe is with, a barrier of plastic. The guys who have treated in there boats for 5yrs. or so probably have the old formula and your OK, he said some of the employees were not aware of how corrosive on soft metals the new treated plywood is but he will try to let everyone know. Man I'm glad I asked before I bought!! Thanks for your help on this one guys!!
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Don,
Looks like at least ONE person at the big box stores understands.
What's interesting is, as well as being boat builders & woodworkers, several of us here are chemists &/or biologists & EMS/Coast Guard folks. Tod O. is a professor (as I recall) along with being a boat builder. Mark W. is a chemist with 3M. I taught Chemistry, Physics, Biology & Adv. Bio. for 10 years. When our relatives were buying a kids play center, made out of timbers and all were treated with the old, very bad chemistry (seems to me is was a cyanate product). I did some searching on the chemistry and .....it's pretty scary stuff. The folks at Home Depot said.......the stuff is ok for a kids play scape..no problem. Well told me about their expertise. You can imagine that I got in a few heated discussions with the relatives on that since it was erected at the lake house (2 of us each have 2.5 acres there on the lake next to each other).
The manu. have changed things but it's still a poison. You want to avoid handling it and then food...etc...etc...etc. Also, do not burn it, the vapors carry the poison.
Lou
 
David, Don't worry this is all new to me and I am going to (Do it right) thanks again for all the answers! I will prob. have more questions as I continue this project.
 
Jeff, I don't have a welder and I have no tools for working alum. so I would have to pay someone to fabricate it and weld it. I just don't have any extra money, way to many bills. But it would have been sweet!
 
Don,

I wouldn't use the PT stuff. The old preservative (CCA) was somewhat corrosive and the new preservative (ACQ) is highly corrosive. The problem is copper. Both contain copper and copper/aluminum do not mix.

I am a fan of MDO. I replaced the transom on my alum. v-hull two seasons ago with MDO. I laminated two layers of 3/4" and then treated it with a paintable, non-corrosive preservative that I purchased from the local lumber yard. Sorry, but I don't remember the name of it. The active ingredient is either propylene glycol or ethylene glycol (anti-freeze agent? -- wear gloves when applying). It acts as both a water-repellant and fungicide.

Lou's FME adhered to the treated MDO just fine and has held up very well. And, with the MDO face, the wood has not checked.
 
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