What is the next best 3/4 plywood when I can't get marine plywood?

[newbury]

I've written in the past of my problems in getting marine plywood in the Northern Virginia area.

The only place I've found wanted like $150/4x8 sheet.

For outdoor projects, non-ground contact where I'll be able to paint the stuff what is the next best with MINIMUM voids in the sheets, both face and interior.
I'm sick and tired of getting sheets with a void in an interior sheet that is half the sheet. That was my last batch of PT plywood.

Or should I switch to Advantech OSB?

 

[Peter 315]

3/4 underlayment does not have voids

 

[TnAndy]

Here they sell a B/B oiled plywood for concrete forming...orange painted edges on it. Not rated for exterior, but with couple coats of oil based paint ( I assume latex paint would peel), depending on the weather exposure, it might do for you.

 

[Steppenwolfe]

I've written in the past of my problems in getting marine plywood in the Northern Virginia area.

The only place I've found wanted like $150/4x8 sheet.

For outdoor projects, non-ground contact where I'll be able to paint the stuff what is the next best with MINIMUM voids in the sheets, both face and interior.
I'm sick and tired of getting sheets with a void in an interior sheet that is half the sheet. That was my last batch of PT plywood.

Or should I switch to Advantech OSB?

I like Advantech, not sure how it paints up, though.

 

[mcfarmall]

MDO plywood perhaps? They use it for road signs and the like.

 

[EddieWalker]

Advantech is about as good as it gets. What are you needing it for?

If you are wanting something for the walls, I would look into Smart Siding. It's cheaper then Advanteck, and has a pretty exterior side, but it's only half inch. If you are looking for sub floor, which doesn't make sense if you are wanting to paint both sides, nothing is better then Advantech. Both are OSB type products, but of a higher grade and quality then your normal 7/16 OSB.

If you are building something else and you are painting it, and 3/4 plywood is the best choice, like a box or some other outdoor furniture, I would just go with construction grade and spend the extra money on really good paint. For filling voids, there are a number of products out there for that in the flooring section that should work, but most of the time, I use automotive Bondo.

 

[John Fitzgerald]

I had some scraps left over from decking grade exterior plywood that we used on a house we built almost 20 years ago. Left some of them out in the weather for several years, unpainted, and very little separation of layers. I think it was 1/2 inch thickness.

 

[RNeumann]

Plywood is rated and marked in a fairly stand way. “A” is smoothest and “D” will have voids. The nicest looking outdoor plywood typically stocked at a lumber yard will be “AC-X” with the “X” being exterior grade.

OSB can be more stable for some applications- it just depends on what you are doing with it.

Paint isn’t the best sealer. I’d be looking at some of the stains- but ask your local paint store.

As others have said, MDO is also nice. It is used to make signs etc that live outside.

 

[newbury]

Advantech is about as good as it gets. What are you needing it for?

That's part of MY problem. A "scrap" needs to be very small before it's tossed.
And often I'll "repurpose" something I've used for 5 years. I've PT plywood and decking that I've been using for 20 years or more, it's finally getting down to pallets for moving stuff.

<snip> If you are looking for sub floor, which doesn't make sense if you are wanting to paint both sides, nothing is better then Advantech. <snip>

That is what I was thinking.

If you are building something else and you are painting it, and 3/4 plywood is the best choice, like a box or some other outdoor furniture, I would just go with construction grade and spend the extra money on really good paint. For filling voids, there are a number of products out there for that in the flooring section that should work, but most of the time, I use automotive Bondo.

The problem is voids under the surface layers. I've had voids over 8 inches by 8 inches separated by only a few inches of wood on the interior layers. When the surface layer separated off the interior layer looked like swiss cheese with large voids.

I had some scraps left over from decking grade exterior plywood that we used on a house we built almost 20 years ago. Left some of them out in the weather for several years, unpainted, and very little separation of layers. I think it was 1/2 inch thickness.

Yup, I've got some of that also, but the several batches I bought for my last Pressure Treated plywood trailer build were the swiss cheese type. That's why I went to marine grade.


Thanks guys for the input. I've just had an inborne hate for OSB, perhaps a good dose of Advantech may cure it.

 

[Tompet]

MDO plywood perhaps? They use it for road signs and the like.

This is correct and worth checking out. Great product to work with, is available faced one or two sides primed and unprimed. If painting primed is worth extra cost. No voids in plys, extremely flat and can be used for exterior trim facades and with the faced side no grain shows and when painted is smooth and basically flawless.

Some lumber yards carry it, most can order. Some sign suppliers stock it. Prices can vary depending on vendor so worth calling around. Also available in 5'x10' sheets, but that is usually ordered in with obvious 4'x8' more readily available.