Do I need to seal the plywood?

[Burro]

My Plywood sides are 3/4" and I was wondering do I need to seal the plywood if I am coving it with aluminum? I picked up a gallon of polyurethane sealer but if I don't need to seal the sides or the roof I would prefer not too. Any suggestions?

If I should seal it what type of sealer should I use? The menards guy suggested using deck sealer, but I grabbed the polyurethane.

[caseydog]

It certainly won't hurt, IMO. Anything you can do to fight water is a good thing. So, sealing your plywood, especially the end grain, will help your TD last longer.

If your budget can handle it, I would say, go ahead and seal the wood even though you will be covering it with metal.

CD

[LDK]

I bought a gallon of CPES from the rot doctor that I'm gonna use. I too am skinning with aluminum. I also used henrys 201 roofing tar on the underside of the floor.

[48Rob]

My Plywood sides are 3/4" and I was wondering do I need to seal the plywood if I am coving it with aluminum? I picked up a gallon of polyurethane sealer but if I don't need to seal the sides or the roof I would prefer not too. Any suggestions?

Hi Burro,

If you cover the plywood with aluminum, will the bottom of the walls (the edge that faces the road) also be covered, or will they be exposed?

As long as the plywood is 100% protected by the aluminum, then no, you don't need to.
Where you attach the aluminum and or edge trims and other parts, injecting sealer into the screw holes is advised as putty can shrink and sometimes screws can loosen and allow water in.

Almost always, when plywood gets wet and fails, the water is drawn in through the edges, so it is inexpensive insurance to up the odds by sealing them.
The polyurethane, if covered by the aluminum should work well.
Thinning it a bit for the first and or second coat helps it penetrate deeper.
You may need 4+ coats. Lightly sand or scuff after each coat, when it becomes very smooth and shiny and looks like it has formed a solid surface water can't get in, give it one more coat.
It doesn't take long to do just the edges, though you should wait a day between coats.

Rob

[wannabefree]

Whether or not you seal the ply is really a question of how long you want your trailer to last and how you will store it. No matter what you do water will eventually get under the aluminum and cause some rot.

If you store your tear inside and only use it in fair weather it will last a long time unsealed. If you store it outside you may begin to see problems after one winter. Sealing the ply is your last defense.

We built our tear to last 30 years because when I will really be in a position to use it I won't have the health to build another. Everything is sealed, inside and out.

[Rlowell]

I think that what everyone is saying is that plywood is very porous and sealing it against the possibility of water is really desired. I used Polly and
paint thinner mix of 1/4 polly and 3/4 thinner and I still had some left
after three coats and I did the edges about three more times to make sure. We do have a lot of rain in Florida even though I am storing my TTT in the garage. Look forward to seeing pictures of yur build.

Rod