Plywood-Exterior Glue?

[Capebuild]

Hello....
How important is it for the baltic birch plywood be constructed with exterior glue adhering the layers together? I can get 4x8 panels which do use exterior glue.
However, the 5x5' panels are not constructed using exterior glue. So, I'm asking, from member's experience, is using a birch ply panel not having exterior glue a
a bad idea?

Thank you.

John

[swoody126]

IMHO pywood delamination is likely one of if knot the most common reason RV's deteriorate

any time you can it is best to use the most durable products available

moisture doesn't require large voids to begin rotting any/all wood it can

as common glues are exposed to moisture they begin to soften and turn loose the parts they were used to hold together

exterior/waterproof glues are your friends when used to make the plywood you use in this type of application

RV's and boats benefit greatly when built of plywoods that were assembled w/ exterior/waterproof glues

ask yourself

¿ how long will it take you and how much will it cost you to disassemble and rebuild WHEN the interior grade plywood fails ?

and now you know the rest of the story

sw

[halfdome, Danny]

I can't disagree with SW's post but from my own experience it's all in how you build.

A good friend has made well over 40 teardrops and used deck paint to seal the exposed edges in the galley walls, etc.
I've seen some of his trailers delaminating, mainly from improper outdoor storage.
I tried to fix one of them and gave up.

The only Baltic Birch ply I use is is in the ceiling and roof and both are properly covered and sealed.

Once I took a scrap of 1/2" Baltic Birch 5 x 5 plywood and soaked it in a bucket of water for an extended time, then in a sandwich bag in the sun.
The plywood did look aged but to my surprise, no delamination.

The plywood that's exposed to the elements (wall bottoms) on my teardrop has aluminum angle with sealant and in the galley wall area matching Plam (plastic laminate) that's covered with the galley lid.
I don't know what kind of glue they used in the 3/4" Pacific Birch Light plywood I used on my walls, but properly sealed, it doesn't matter to me.
Danny

[saltydawg]

What is this plywood you speak of?

slowly backs out of thread...lol

[saywhatthat]

At the shop about 75% + damage is wood delamination and rot. Condensation in the fibers can start the rot exterior/waterproof glues is a must.

[Tom&Shelly]

Hello....
How important is it for the baltic birch plywood be constructed with exterior glue adhering the layers together? I can get 4x8 panels which do use exterior glue.
However, the 5x5' panels are not constructed using exterior glue. So, I'm asking, from member's experience, is using a birch ply panel not having exterior glue a
a bad idea?

Thank you.

John

We used the 5 x 5 Baltic birch on the exterior walls of our build, but then covered it all with fiberglass and epoxy. That's a common building method here, and I've never heard of a problem with delamination. I'd think a bigger problem is that, if water somehow does get into the wood eventually it will rot, regardless of the glue.

But, we're just getting ready for our first trip, so I'll have more credibility when I say something in about ten years.

Tom

[halfdome, Danny]

What is this plywood you speak of?

slowly backs out of thread...lol

Pacific Birch Light plywood was carried by Crosscut Lumber in Washington & Oregon, it weighs 48 pounds for 3/4" 4' x 8' sheet.
I haven't seen it in some time. I've used 3/4" Birch plywood in the past and it held up.

I use aluminum "C" channel gooped up with OSI Quad sealant available at Home Depot.
I mount the "C" Channel with stainless screws with the threads gooped up with sealant.

Danny

[breb]

Hi John
I won't say that Baltic birch ply won't delaminate but there are ways to preserve that sheet stock and I'm one that used baltic ply. I did use the mix, Mine was 25/75 % spar and mineral spirits.
2 coats and then a third at 50/50 . I was very particular with souping up the edges in the process. All exterior was given that treatment even in my core in the roof where the insulation is .
Also all spars . For me there was time and it seemed like a reasonable way to offset any water intrusion that might find it's way in. The trailers that i've seen in the past where there was plywood involved, most were intact , the point I'm making is that time will take it's toll but the glues and processes that are being used today are better then years ago. My dad had an old moon trailer (40ish) in the late sixties. It had ply all inside and was quite solid when he sold it in 1972. I think also your exterior is your first front for warding off water so what ever your method or exterior
special attention is necessary . Mine is all under Aluminum coil stock.

[GPW]

I’m with Breb … the “Mix” has saved us many times … In our ultra soggy climate , everything possible must be done to prevent water intrusion and Rot . Drip edges , diverting all water, moisture and dew off the trailer are essential …

Here , plywood always fails us eventually , and we’ve had better luck with the Mix treated OSB , and we’ve finally installed a “Board” ( 1X8 ) floor which has been no trouble at all … and living Outside for almost 8 years now …

And then , there’s always Foam …

[MickinOz]

Obviously, there are people who think the best way to avoid delaminating plywood is to not use any (yes, I'm looking at you Dawg ).
And yes, they are correct.

However, for me, part of what makes a teardrop so cool is the timber.
It just does. As much as there are all sorts of things I'd do different if I built mine again, laying back in that timber cabin makes it all worthwhile for me.

But, I have had time to ponder - and my conclusions are the same as many another.
Get the best ply you can, and regardless of what you intend to cover it with be it paint, clear finish, PMF, aluminium sheet, definitely made with water proof glue and rot resistant wood.

I got reasonably good quality exterior grade slash pine plywood with waterproof glue, and saturated everything with the mix. I'd still go for a higher grade ply next time - if I could find it.

[Capebuild]

I did just last week make my plywood purchase. Taking what everyone had said on this topic, for the 4x8 sheets of Baltic Birch ply (which will be used mostly for the cabinetry),
I was able to purchase it in exterior grade which used exterior glue. For the middle interior wall sections I purchased 4x10 sheets of MDO board, which is exterior grade with exterior glue.
For the 1/4" and 5/32" sheathing panels for interior/exterior wall sections, I purchased 5x10 Okoume. Pricy but bit the bullet. Very light weight material. They didn't have 1/8" so got the 5/32".
I also purchased 1/4" thick 5x5' sheets of Baltic Birch which are NOT exterior glue. Those will be used for sliding doors, some trim, etc. I figure the parts that are used from this 1/4" material can always easily be replaced
if need be. I may still purchase some 1/2 inch baltic birch for some of the cabinetry walls.... when I get to it, I'll deal with it then.

Also had the steel delivered to weld up the chassis frame.

Guess I'm officially underway!

John

[Juneaudave]

I thought I heard a wallet sizzling!

[TimC]

Can't wait to follow your build journal. The detailed planning and design are going to pay off with a high quality teardrop.

Tim