Pressure treated wood in boats-

[Dutch]

Southern yellow pine - Why isnt it suitable for framing members assuming you pick over carefully for the best vertical grain knot free, and free of bow, warp and etc. stuff and air dry it for a year or so?

[Jim Ledger]

That's a good question. I have a stack of sixteen foot, 5/4x6 CCA SYP decking. Each one at least six rings per inch, vertical grain, straight grain and completely knot-free. Home Depot, fifteen dollars each.

How about glueability with epoxy?

[Gib Etheridge]

I would use it in a minute. I think I saw the Gugeoun Bros. tested it with their epoxy and found them compatible. You could call them for confirmation.

Some PT needs to be fastened with stainless rather than hot dipped galvanized. 18/8 will work for a boat that is going to be stored dry, it's what the building code requires here for decks and it lasts just fine, which makes it readily available for cheap in the lumber yards here. 304, or better yet 316, is better for continuous exposure to salt water. I don't know about the compatibility of any of the various pressure treatments and copper, bronze or monel.

[Duff]

Supposedly too wet for epoxy, someone will come along and give you the exact numbers. But I used it for a floating dock last year, half lapped joints with West Systems epoxy and galvanized through bolts, and all the joints are still tight. Of course, I'm not bobbing along with the trade winds in the middle of the Pacific, either.

[tomtoledo]

I'd like to know too...Maybe one of the experts on here will answer...All I know is the guy with the wooden cruiser next to me at the yard is replacing his rotten frames with pressure treated lumber that he bought at Home Depot, while I'm spending $$$ at the lumber yard on douglas fir and mahogany....but I draw the line at using the zink plated fastners that he's obviously buying there too.....

[Bob Smalser]

If you removed all the pressure-treated SYP and galvanized carriage bolts from the shrimp and work boat fleets of the deep south, they would all sink at their moorings.

The issues when using the same in yachts are the treated wood eats fasteners, creating rust streaks with galvy and 18-8, is often too wet to take paint in a timely manner, and is prone to warpage. When the boards squirt water when driving nails, you know the stuff is a bit wet for glue and paint and also might move, twist and cup a tad as it dries in service.

If you can correct for those problems by airdrying, etc, then have at it. But note that the Universal Building Code has changed a couple of times in the last decade because fasteners aren't holding up well in treated wood. And those are houses on dry land, not boats in salt water.

[Mark Reuten]

The primary reason not to use pressure treated woods in boats is that the species used in those products have lower durability (rot resistance) than those traditionally preferred in boat building such as long leaf yellow pine or pitch pine. Here is Canada white spruce is often used for pressure treated products. The manufacturing process can only drive the chemicals products so deep. You can clearly see this when you look at an end-cut and why all manufacturers specify that you treat end-cuts with preservative. The structure of a household deck is exposed to a lot of air movement which helps to combat fungal development. A boat is much less ventilated and sitting in an environment with much higher ambient humidity. This is why we are always fighting rot problems. The guy using the pressure treated wood in his boat is saving a couple of bucks now but I believe his efforts are largely wasted as the repair wont last nearly as long. Then again, people have budget constraints and want to get out on the water and so do their best within their resources. I'm not against quick, dirty and cheap boats but they must be held to a different standard than those built with longevity in mind.

[keith66]

Ten years ago i built a pair of GRP rowing Gigs, they were built on the cheap & the gunwales were made from 1" x 1 1/2" roofing batten, its pressure treated Larch & was cheap as chips. A couple of coats of woodstain & it looked like Mahogany, still sound after ten years.

[pipefitter]

Most every mullet seine skiff I ever saw was built using PT framing. Not the smaller dimensional sizes, but that ripped from larger 2x stock. Most didn't bother to glass over it at all on the interior. Just alkyd enamel.

[waltwood]

Because I work with it daily, I have kept up with the changes in treated lumber. Treated wood has changed several times in the last few years. ACQ was the treatment that was causing the rapid corrosion of fasteners and it is no longer used. When arsenic was found in playgrounds, the industry was asked to stop using CCA and they did. They hastily started using ACQ without enough testing and it had major problems with corroding fasteners. It has not been used for about 3 years now depending on the area where you live.

[Dutch]

That's a good question. I have a stack of sixteen foot, 5/4x6 CCA SYP decking. Each one at least six rings per inch, vertical grain, straight grain and completely knot-free. Home Depot, fifteen dollars each.

How about glueability with epoxy?

well I for one have seen it hold up for 15 years with good adhesion to ply via gluvit

[Paul Pless]

If you removed all the pressure-treated SYP and galvanized carriage bolts from the shrimp and work boat fleets of the deep south, they would all sink at their moorings..

To be slightly more accurate most of the shrimpers I've seen have a fair amount of glass and googe over everything. Not really encapsulated - more like a second heavy scantling fiberglass hull built around a slowly rotting away wooden boat. . .

[shade of knucklehead]

I use Pressure treated for posts and deck beams. That is all. We air dry it for at least a year if we can. For ribs and frames we use something harder, usually Jersey white oak, or mahogany.

[hokiefan]

If you removed all the pressure-treated SYP and galvanized carriage bolts from the shrimp and work boat fleets of the deep south, they would all sink at their moorings.

The issues when using the same in yachts are the treated wood eats fasteners, creating rust streaks with galvy and 18-8, is often too wet to take paint in a timely manner, and is prone to warpage. When the boards squirt water when driving nails, you know the stuff is a bit wet for glue and paint and also might move, twist and cup a tad as it dries in service.

If you can correct for those problems by airdrying, etc, then have at it. But note that the Universal Building Code has changed a couple of times in the last decade because fasteners aren't holding up well in treated wood. And those are houses on dry land, not boats in salt water.

This is no insignificant issue. I've used a lot of pressure-treated pine for decks, sheds, fences, etc. Some boards you buy are light, stiff, and dry. They've been in the pile for a long time. Others are damp, bendy, and heavy as a brick. And yes they squirt when nailed!!! I wouldn't trust those with glue for a minute. I'd do some research on the fastener corrosion issue before I used it in a boat.

Cheers,

Bobby

[AndreasJordahlRhude]

The primary reason not to use pressure treated woods in boats is that the species used in those products have lower durability (rot resistance) than those traditionally preferred in boat building such as long leaf yellow pine or pitch pine. Here is Canada white spruce is often used for pressure treated products. The manufacturing process can only drive the chemicals products so deep. You can clearly see this when you look at an end-cut and why all manufacturers specify that you treat end-cuts with preservative. The structure of a household deck is exposed to a lot of air movement which helps to combat fungal development. A boat is much less ventilated and sitting in an environment with much higher ambient humidity. This is why we are always fighting rot problems. The guy using the pressure treated wood in his boat is saving a couple of bucks now but I believe his efforts are largely wasted as the repair wont last nearly as long. Then again, people have budget constraints and want to get out on the water and so do their best within their resources. I'm not against quick, dirty and cheap boats but they must be held to a different standard than those built with longevity in mind.

The reason it was treated is because it has little or no decay resistance. If it was "durable", it would not be treated. Do not use refratory species (difficult to treat) that have been treated. If the chemicals only create an envelope around the perimeter of the wood, don't use it. Get a species that is easily treated, such as Southrn Pine and Norway/Red Pine. And use the proper treatment type and retention for the particular application.

Andreas

[AndreasJordahlRhude]

Of course pressure preservative treated wood can be used in boats. It is all the time.

The orignal post did not mention anything about gluing, but since someone brought it up... Would you try gluing on a piece of dripping wet untreated wood? No, of course not. So why would you try gluing on a dripping wet piece of treated wood? Make sure the moisture content of the wood is combatable with the selected adhesive - whether using untreated or treated wood.

Andreas

[Jim Ledger]

In the case of my CCA decking, it has been air drying for a year so it's not likely that moisture would be an issue. My question concerned the effect of the preservative on the glue bond, either epoxy or resourcinol.

How do silicon bronze fasteners stand up to preservatives? Being copper based they hopefully fare better than galvanized.

[Gib Etheridge]

Jim,

I just read several pages of recommendations after Googling "CCA and silicone bronze" and learned that;

You're in luck. While CCA is not used very much anymore because it releases arsenic into the environment it is the least corrosive of the pressure treatment chemicals.

Recommended fasteners are, in this order; hot dipped galvy for use where moisture content does not exceed 18%, stainless (304 and 316), silicone bronze and copper where moisture content exceeds 18% and where exposed to sea water.

Did you call Gougeon Bros. to confirm epoxy compatibility?

[Bob Smalser]

The Goo Brothers will tell you wood has to be at 12% to achieve full strength with an epoxy bond, and that CCA or other treatments short of oily ones like old-fashioned creosote or kerosene-based copper preparations will all glue just fine.

But the glitch is the 12%, not the CCA. Porous wood like hemlock and yellow-pine sapwood is sawn, kilned to 19%, then pressure treated with water-based poisons of one flavor or another. The end result is nowhere near the 12% required for epoxy, and a few months stacked and stickered may not get it there either.

Y'all need a good moisture meter if you intend to glue this material. Hope is not a management tool.