why not pressure treated?

[rockyrude]

I am getting ready to reinstall my stringers and deck. I have seen a lot of discussion about materials and have noticed there seems to be a large group against pressure treated. Will there be an unwanted reaction with the resins? Will the resins not adhere to pressure treated? Thanks in advance

 

[Bondo]

Re: why not pressure treated?

Ayuh,.............

I know many here Don't think it's a Good Idea,.......
But,.......
The Resto-work I did in 1999 with P/T Plywood,+ Epoxy resin still looks like it was Just completed............
The boat has over 700hrs. use since then too....

I had to let the wood Dry out for a Long Time,.....
And,.....
Polyester Resin might also be a different story.......

 

[Robj]

Re: why not pressure treated?

Many here say not to use pressure treated wood. When I did my restoration, I did alot of research before I decided to use PT ply for my stringers. I found no reason not to use it. Poly resin sticks fine, just make sure that the wood it dry, below about 12% moisture. I tested it and the wood failed before the poly bond did. I cut mine stringers into the required widths and let it dry indoors for over a month before glassing it in. Try and get CCA treated wood, not to sure of the new ACQ stuff. I would also use stainless fasteners.

Have a great day,

Rob.

 

[rebuilt]

Re: why not pressure treated?

Kiln dried treated CAN be bought. But it's hard to find, and expensive. Or, you can dry your own, like Rob J did. I just went to Lowe's, and bought KD white cedar for the stringers and cross braces.. It's supposedly less oily than red cedar. The original lumber in mine was plain old pine. Mine was built in Florida. I have read that the glass to the stringers is more of a form to hold them in place, than a real bonding process. I've also read more times than I can count, that a good grade of 5 ply exterior plywood is the choice for decking. So that's what I chose. In one of his previous posts, Rob J chose exterior ply for decking as well. A properly applied glassing and topcoat will waterproof your plywood, so why even bother trying to dry out a couple of full sheets of treated? Keep her covered, and it won't be a problem anyway. Good luck. KR

 

[BillP]

Re: why not pressure treated?

PT nay sayers just aren't up on modern times and unfortunately they are in the majority when it comes to opinions on using pt in boats. Old pt processes (creosote) used petroleum products that resin wouldn't stick to. Newer processes (CCA the last 25-30 yrs) eliminated petroleum for most pt processes and resin will stick to it same as non treated wood. Last time I checked only railroad ties were still using creosote.

Production boat builders have been using Greenwood Products CCA pt for decades with polyester resin. The American Plywood Association (APA) has research papers on the subject that anyone can read. Briefly said, they tested the CCA process with polyester resins and found the bond strong enough to pull wood off instead of the resin pulling away by itself. It was the same bond strength as on non treated ply. There's tons of credible info out there that debunks the typical negative comments about pt not being suitable for boat stringers, transoms, floors, etc. The only real issue is making sure the wood is dry before glassing.

With that said, I did a complete rebuild (transom, stringers, floor) using CCA pt several yrs ago and it still looks perfect.

 

[rockyrude]

Re: why not pressure treated?

Thanks for all the input. Even tho it's a fourty year old and I may not see the next fourty, I want to the very best for it.