Drying out PT ply?

[erikgreen]

Does anyone have a good way to dry out PT ply without it warping?

I was thinking of putting my precut pieces on a flat concrete floor, with furring strips supporting them but allowing airflow under and between, then more furring strips supporting weights on top, and pointing a fan or heater at the whole stack.

I've tried to store it flat, but it gained moisture in my garage and warped a bit as it lay there. I'm going to re-laminate my transom this weekend, and I need the wood fairly dry before I epoxy it and seal the moisture in...

Erik

 

[Robj]

Re: Drying out PT ply?

Hello there

I put wood strips underneath and between layers with weights on top. It took a month indoors to dry out. I don't see any possible way other than inside a kiln to dry your pt ply by this weekend. Personally, if you are using epoxy, I would just use kiln dried exterior grade fir plywood. Epoxy will seal it and prevent the water from getting inside. I don't think you need the pt in this case.

Have a great day,

Rob.

 

[Mark42]

Re: Drying out PT ply?

I took a piece of 1/2 inch TP plywood and nailed it to the studs in the garage. If your walls are sheet-rocked, put a 2x4 spacer in two or three places then tack in place. That will let the air get behind it.

 

[tashasdaddy]

Re: Drying out PT ply?

i would not use treated, the chemicals eat the metal fasteners that go thru it. this is a big problem in the construction industry today.

 

[burroak]

Re: Drying out PT ply?

Placing PT plywood on a basement concrete floor is a counter productive endeavor. Moisture wicks through concrete from the ground below. Place a sheet of plastic film on a concrete floor for a couple of days and check it out, it will be wet. The temperature in a basement doesn't promote drying either.

I would screw the plywood to the rafters in the garage; good heat, lower humidity, and a flat surface. As to the use of PT and its corrosive effect on fasteners, it will do that. To mitigate that condition use stainless fasteners or a fastener coated to resist corrosion. Fastenal distributors have quite a selection.

 

[erikgreen]

Re: Drying out PT ply?

Since the wood is actually part of the transom, I was planning on leaving it fully encapsulated to prevent water ingress, which would also protect the fasteners.

But, I'm not wild about putting wood with a relatively high moisture content in and sealing it up. I think I'm going to go with some exterior grade instead, since it'll be dry (and as a bonus, flat, since I'll get it fresh from the bundle). I can use the PT that I cut already to fit as a template for the dry stuff.

I doubt I'll be able to really dry off the PT I bought for the deck, either, which means I either put that in wet or use something else. There goes $200 worth of PT ply :\

Oh, well.. at least I won't have knots showing in the deck.

Erik

 

[tashasdaddy]

Re: Drying out PT ply?

erick the chemical used to treat the pt is extremely corrosive to the metal fasteners, anywhere it contacts the metal even in the sealed transom. you see pretty nuts and bolts on the outside, but inside they are decaying. then one day the heads and nuts, just fall off.

 

[erikgreen]

Re: Drying out PT ply?

To clarify, no fasteners would actually touch the wood... glass would be the only structural fastening, and all through holes and screws are going to be pre-drilled and lined with epoxy/wood flour mix for "waterproofness".

But I would have liked to use screws on the decking to save some time here and there. I suppose it doesn't matter with the wood being wet and all anyway. I'll just build a wood rack and save it for garage repairs or something.

 

[klos]

Re: Drying out PT ply?

I'll just build a wood rack and save it for garage repairs or something.

That?s a good idea. IMO there to no place for PT in a boat and encapsulating in glass/resin.
I've seen some repairs made with PT that was thought to be completely dry on the outside. Two years later the core material was mostly mush.

The outer layers of ply can dry with in a few weeks but I would think the inner layers could take months.

Use a good quality exterior grade Douglas fir plywood. If you encapsulate the wood then there should be no worries about water getting in.