Will Luan fall apart in the rain?

[tscarbroughdc]

I am closing in on being finished with my Benroy. Seems like it's been a long 4-5 months.

I'm posting a few pics as I'm proud of the work I've done. This is the first time I've built anything pretty much!

Anyways a carpenter friend of mine said that the Luan roof on my camper will fall apart in the first rain or even a heavy dew!

Is that right? What do I need to do to protect the top?

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[citylights]

Any wood will deteriorate in the rain. regular plywood probably even worse, marine grade plywood less.

At a minimum you need to seal and paint it. For a woody, you would clear coat it.

At best you apply a finish over the top of it, like an aluminum skin.

[S. Heisley]

It will start to delaminate in about 10 to 20 minutes in the rain! Get some epoxy on it and then at least some paint and get it well sealed. Anywhere that your plywood isn't protected or anywhere that water can get in, it is definitely liable to delaminate. Some luan is worse than other luan, depending on the quality of the glues; but, you can't leave it bare like that.

[tony.latham]

I've got a 4x10 commercial built tear that I bought in 2004. It's covered in aluminum and finished with laquer on the interior. I've had some water issues with the laquered surfaces and have since redone them with polyurethane. Anywhere water could get to the plywood –especailly back under the hatch, it's caused problems and I've had to seal those areas with epoxy –the liquid stuff used in fiberglassing. I think part of that problem was that it was built with interior grade plywood.

On my 5x10 build that was one of the issues I wanted to address. All the interior surfaces are sealed with three coats of polyurethane. The exterior is covered with aluminum. However, under the aluminum I sealed the side/roof edges with expoxy/fiberglass bias tape. The rest of the exterior wood is sealed with two coats of Raka epoxy. I bought the 1.5 gallon "thin" kit and the wood sucked the first coat up as if it were water. I'd be curious to know how deep the stuff ended up! I think my epoxy was $80 (and buy their pumps too –much easier to mix).

Take a scrap of that luan and throw it in a bucket of water.

Tony

[rowerwet]

I build boats out of luan,
I use exterior porch and floor paint, the only epoxy used is to glue the seams together. As long as you don't let the paint wear through or get the wood damgaged it is fine. bare it won't last long.
I use sureply which is made with waterproof glue, but the top plys will start to warp and wrinkle if they get wet no mater what.
my tear has paint and canvas for the skin, works fine.

[oakinteriors1]

I have built boats also...And EPOXY is the only way to go with that stuff.....
But on the other hand Baltic Birch ..I have a test pc. of 1/2'' ply.. unfinished screwed to a fence post outside for at least 5 years now with NO sign of delamination....

[tscarbroughdc]

Would one of you please post a link to what all you're advising that I use so I can get the right thing at the store?

[tony.latham]

Would one of you please post a link to what all you're advising that I use so I can get the right thing at the store?

http://store.raka.com/6quartkit.aspx

Read up on epoxy application on this forum while your stuff is shipping, but here's some quick advise:
1. Buy their pumps 'cause the ratio is 1:2, makes it much easier to mix a batch.
2. Once mixed, pour it in a disposable paint roller pan. In a confined container, the mix produces enough heat that it can start to go off within minutes.
3. You can apply it to the tear with a foam roller but have some plastic squeegees on hand to help move it around. You can get these at an automotive store near the Bondo.
4. Wear a pair of nitrile gloves. Cleanup with aecetone.
5. You can apply other coats without sanding if you apply within 24 hours, otherwise you need to sand.


TL

[Larry C]

You may get by using epoxy only to seal the flat sides, but I would glass the top even with thin glass (2 oz) The CHEAP Luan on the top that is curved will start to splinter when exposed to moisture and the sun.
Fiberglass will help stabilize the ply skin. Also, I would tape the seams with fiberglass.

Good luck...

[tony.latham]

I agree with Larry C on this. I used his method to cut bias fiberglass strips to seal my sides/roof and it worked well. You can read his bit on it here: viewtopic.php?f=21&t=34887&start=0

Scroll down to: "I stopped using fiberglass tape for kayak building a long time ago. It is much easier to make your own. If you dont already have a fabric cutter..."

[Roly Nelson]

I built my 1/2 Nelson woody over 10 years ago, using only laun plywood. It has over 30,000 miles on it in all kinds of weather, snow, sleet, driving rain and so on. I have only spar varnish for protection, and so far, absolutely no delamination what so ever. I lightly sand my treasure once a year and slap on another coat of varnish, which makes it look like new again. I am fortunate to have the ability to store it out of the nasty weather, here in So Calif, and am presently building another Luan camping trailer. Good luck on your build.
Roly, the li'l ol' So Cal woody guy