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Pressure Treated Plywood verses Marine Plywood

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james...@earthlink.net

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Dec 2, 2002, 9:04:41 PM12/2/02
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I'm replacing the rear flooring in my 12 year old bowrider. (Along with
a little re-upholstery work.) It has a few soft spots but not
completely rotted out. I blame the injected foam and lack of drain
holes across the stingers. Water has definately been trapped in the
compartments under the floor for a long time. Foam I will remove, drain
holes I will add.

But to get to the point. I'm really leaning towwards using pressure
treated plywood instead of marine plywood. I know the pressure treated
stuff may have some voids but for the floor I'm thinking that is not a
major factor. I just hate to put something back in that rotted once
already and the composite stuff is just too expensive. So what is
everyone's experiences and opinions on these two choices. TIA :-)

Harry Krause

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Dec 2, 2002, 9:06:56 PM12/2/02
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Find some XL plywood. That's the best.
http://www.greenwoodproducts.com/contact.htm

Gfretwell

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Dec 2, 2002, 9:39:01 PM12/2/02
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I talked to Wolman (the folks who make pressure treated plywood) and they would
not recomend it for my pontoon boat. They said pressure treating was to stop
bugs, not rot. They also said the treating might actually cause plywood to
delaminate.

james...@earthlink.net

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Dec 2, 2002, 9:40:03 PM12/2/02
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Oops, sorry I should have mentioned, I'm in Raleigh NC so any solutions
need to be somewhat local to the middle east coast. 4x8 sheets of
anything are a bit expensive to ship :-)

Joe Allison

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Dec 2, 2002, 9:49:44 PM12/2/02
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Use StarBoard. It will last forever. Its expensive but you will never
replace it. West Marine sells it.

Calif Bill

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Dec 3, 2002, 1:52:19 AM12/3/02
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XL is pressure treated Plywood. My 1991 boat has the floor made of treated
Plywood. Is still in good shape. I am looking at replacing it, as the
vinyl covering is looking a little worn. The bvinyl is the Nautolex.
Available from West Marine and SeaPower.
Bill

"Harry Krause" <harry...@hotmail.com> wrote in message
news:tBVG9.35843$oa.17...@news1.east.cox.net...

> Plenty of that product is available in NC.
>


Chief3mfc

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Dec 3, 2002, 7:49:15 AM12/3/02
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>So what is
>>everyone's experiences and opinions on these two choices.

When I was looking for the best material for the sole in "Anna Marie", my
research indicated that pressure treated ply had a tendency to delaminate. Even
if sealed with resin. Seems that resin doesn't like to stick to it.
Starboard would've been the ideal material, but would have cost waaaay more
than I was comfortable with. If I remember correctly, it was in the
neighborhood of $1200.00 just for the materials. Pricey for a 20' boat.
The best solution I found was exterior grade plywood, cut to fit, painted with
2 coats of resin. I thinned the first coat so it would soak into the ply.
Waited 24 hours and applied the second coat.
After it was screwed in place I put 2 layers of stiched mat on top. Then a
light sanding and two coats of polyurethane paint. Then the carpet over top of
that.
Hope this helps.

Cliff

D Fortner

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Dec 3, 2002, 9:05:13 AM12/3/02
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Your method is the correct method.
1) You can't coat the PT plywood with anything because of the arsenic in it
and it tends to delaminate (PT is to prevent bugs, not rot).
2) Starboard, while wonderful stuff, is to slick and to soft for a boat deck
in my opinion.
3) When glass encapsulating like you did, I don't feel that there's a need
to spend the money for marine grade, exterior is OK.
4) Remember to use EPOXY resin on any horizontal surface (I pretty much only
use epoxy on everything). Polyester resins absorb moisture and will
eventually delaminate from the wood.

Later . . .
Dave Fortner


"Chief3mfc" <chie...@aol.com> wrote in message
news:20021203074915...@mb-mc.aol.com...

Don

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Dec 3, 2002, 1:09:12 PM12/3/02
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I think you're confusing "rot" with "waterproof". The fungi that rots wood
as a result of being exposed to water for long periods IS prevented by using
PT woods. The same chemicals that repell the insects kills the fungi.

Funny Wolman would tell you such a thing since they brag about how their
product "protects from rotting". LOL. They probably just didn't want a
claim against them should something happen. If I'm not mistaken, I think
quite a few pontoon maufactures USE PT plywood.

I don't think marine grade plywood has that ability. I'm not sure but isn't
it simply a high-grade plywood? No chemical treatments in it at all?(Like
the CCA that is used in PT)

Don

<gfre...@aol.comnospam> wrote in message
news:20021202213901...@mb-fc.aol.com...

james...@earthlink.net

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Dec 3, 2002, 7:24:49 PM12/3/02
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I'm game Harry. But so far all I've found is regular marine plywood. I
found a local lumber company that has two grades at $32 and $46 a
sheet. Know anybody specific around Raleigh that has this PT stuff?
Everyone seems to think that the regular pressure treated plywood has a
tendency to delaminate so I guess that's out. Think painting the marine
plywood with the rot dr's penetrating epoxy would extend it's life?
Story is getting worse but that's a new topic :-(

Harry Krause wrote:
>
> james...@earthlink.net wrote:
> > Oops, sorry I should have mentioned, I'm in Raleigh NC so any solutions
> > need to be somewhat local to the middle east coast. 4x8 sheets of
> > anything are a bit expensive to ship :-)
> >
> > Harry Krause wrote:
> >
> >>james...@earthlink.net wrote:
> >>
> >>>I'm replacing the rear flooring in my 12 year old bowrider. (Along with
> >>>a little re-upholstery work.) It has a few soft spots but not
> >>>completely rotted out. I blame the injected foam and lack of drain
> >>>holes across the stingers. Water has definately been trapped in the
> >>>compartments under the floor for a long time. Foam I will remove, drain
> >>>holes I will add.
> >>>
> >>>But to get to the point. I'm really leaning towwards using pressure
> >>>treated plywood instead of marine plywood. I know the pressure treated
> >>>stuff may have some voids but for the floor I'm thinking that is not a
> >>>major factor. I just hate to put something back in that rotted once
> >>>already and the composite stuff is just too expensive. So what is
> >>>everyone's experiences and opinions on these two choices. TIA :-)
> >>
> >>Find some XL plywood. That's the best.
> >>http://www.greenwoodproducts.com/contact.htm
>

RichG

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Dec 3, 2002, 8:18:28 PM12/3/02
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I think you have to factor in the extra weight added by "treated ply". Also
XL is available in every home center out there. Some people say that even
the "interior" grades of plywood have the same XL glue. I, personally
wouldn't take the chance to save a few bucks.

You are correct, however, in not relating XL glued ply (preventing
delaminating) to "rotting" ply. They are two different things. A zillion
boats have been built, using marine grade or XL grade ply. The major
difference in marine grade is the lack of voids. For flooring, I'm not sure
how that is critical.

If you have removed the offending foam; added seep/weep/drain holes where
needed... there is no reason why the XL plywood would be subjected to more
than a splashing of water for a short time. Now, if you cover it with
carpet, and leave the carpet wet...then you are back to creating the rotting
conditions.

I imagine that the "treated" ply would resist the rotting for a while, but
might delaminate. The solution is always the same. Don't let wet stuff (
carpet, standing water etc. ) stay on plywood for long. If you can't deal
with that, then you have to go the route of epoxy coating and maintaining
that coating no matter what. A properly set up boat, with proper drain
holes and tilted up when sitting on a trailer so that the decks run dry at
rest will not give you the problem that you previously experienced. IMHO.
--
RichG
rgr...@houston.rr.com
-


GAZ

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Dec 3, 2002, 8:17:12 PM12/3/02
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take your wood questions to rec.boats.building and you'll get a lot more
and better informed information.
Gordon

<james...@earthlink.net> wrote in message
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Greg O

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Dec 3, 2002, 8:28:49 PM12/3/02
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"Gfretwell" <gfre...@aol.comnospam> wrote in message
news:20021202213901...@mb-fc.aol.com...

Strange, My dad built a house a few years back and used a couple of scrap
pieces of 5/8" PT plywood for a side walk. It laid in the weather, just
laying on the dirt for ten years until he got the ambition to put in a
concrete side walk. The plywood was almost like new, other than the wear and
tear from walking over it for that time. No delaminating, solid as new.
This was PT for building a "wood" foundation for a home. I wonder if there
are different grades of PT plywood? I know there is different grades of PT
wood for posts and fences.
Greg


Gould 0738

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Dec 3, 2002, 9:17:48 PM12/3/02
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If you can get marine ply for under a buck a square foot, why the angst?

$46 for a 4x8 sheet? Go for it.

Whatever you'd save by using cheaper wood, it won't even amount to $46 a sheet.

In my opinion, no contest. Use the best material you can buy and save the labor
associated with an early re-do.


Gould 0738

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Dec 3, 2002, 9:19:03 PM12/3/02
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Acutally, my math is wrong.

You are talking a bit more than a buck a square foot, but not enough to make a
difference.


james...@earthlink.net

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Dec 3, 2002, 9:43:02 PM12/3/02
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It's not that I'm against the marine plywood, it's that it was marine
plywood that rotted. While they seem to use good glue in marine plywood
it is not treated in anyway to stop rot.

james...@earthlink.net

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Dec 3, 2002, 9:48:42 PM12/3/02
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While searching for XL I found at least a half dozen boat builders are
using it. But I'm thinking none of them are into selling plywood to
consumers. I need to find someone that stocks it for resale and I'm not
having any luck with that.

Harry Krause wrote:
>
> james...@earthlink.net wrote:
> > I'm game Harry. But so far all I've found is regular marine plywood. I
> > found a local lumber company that has two grades at $32 and $46 a
> > sheet. Know anybody specific around Raleigh that has this PT stuff?
> > Everyone seems to think that the regular pressure treated plywood has a
> > tendency to delaminate so I guess that's out. Think painting the marine
> > plywood with the rot dr's penetrating epoxy would extend it's life?
> > Story is getting worse but that's a new topic :-(
> >
> >
>

> I believe Grady-White and Parker use the XL brand of ply. I really don't
> know anything about painting it...both of those manufacturers encase it
> in fiberglass.

james...@earthlink.net

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Dec 3, 2002, 10:12:40 PM12/3/02
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Hope you have better luck than I had trying to buy a new gas furnace for
my house! Are you a 'licensed fusion reactor installer' :-)

Harry Krause wrote:
>
> Ok...you guys have convinced me. I'm going to buy a small fusion reactor.

Gfretwell

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Dec 4, 2002, 12:34:54 AM12/4/02
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>> I talked to Wolman

>I wonder if there
>are different grades of PT plywood? I know there is different grades of PT
>wood for posts and fences.

They have a PT plant here in Ft Myers and they said they would treat any
plywood I brought them but then they said I better be prepared for it to
de-laminate.
They also said the PT was not going to give me enough protection to justify the
risk of delaminating it.
I ended up using MDO plywood, the stuff they use for reusable concrete forms
and such that has a sealed side. It is 12 years and counting on the deck of a
salt water pontoon boat. When I painted and repowered the boat this spring the
wood was still OK and I went with it.

Skipper

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Dec 4, 2002, 9:33:39 AM12/4/02
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Harry Krause wrote:

>> Harry Krause wrote:

> No, but I've got connections at the Steamfitters Union...

A buddy in my youth later became a member and very vocal supporter of
the Plumbers Steamfitters & Refrigeration Local 469, then known as the
Plumbers and Steamfitters, Local 469. We had many friendly debates,
often over more than a few drinks. He contended that the union was is
salvation, and I was engaged in union avoidance.

His preferred out of town jobs on pipe lines and power stations. He
would attempt to certify as a welder and then go as a fitter when he
invariably failed the weld xray exam. He bragged of the high pay, fights
with scabs, and ass time.

We lost him about 10 years ago when he picked someone up in a bar one
night and flew her out to the under construction Palo Verde Nuclear
Station in his private plane for a trist. Seems someone parked a
bulldozer out in the unlit field where he was attempting to land.

--
Skipper

Dan Krueger

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Dec 4, 2002, 7:30:59 PM12/4/02
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I think you are either replying to the wrong post or I need a beer.

Dan

Harry Krause wrote:
Harry Krause wrote:
james...@earthlink.net wrote:

While searching for XL I found at least a half dozen boat builders are
using it. But I'm thinking none of them are into selling plywood to
consumers. I need to find someone that stocks it for resale and I'm not
having any luck with that.


I'd call a couple of the manufacturers and ask them who their supplier
is. Then I'd call the supplier. Gotta be someone in their areas, eh?
Or call the XL factory and ask. It's not a secret.

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