Is a Treated Deck ok?

[Dennis1958]

I would like to use a treated plywood deck on my 18' fishing boat if possible. I can get this at the local hardware store but if it will fail in 5 years then I will do it
the hard way and use marine grade. Has anyone had problems with treated plywood failing after a few years?

 

[DJ]

Re: Is a Treated Deck ok?

Any wood will eventually fail if left wet. Also, the wet/dry cycle will cause dry rot.

If you are leaving the wood exposed, treated is OK. If you are glassing over it or installing carpeting, treated does not accept glues/epoxies very well.

 

[dmarkvid2]

Re: Is a Treated Deck ok?

Regular extierier plywood is good to use as decking, as long as you protect it from the elements by coating both sides, and edges with an epoxy. I would also fiberglass the top side. The only time I would use a marine plywood is if I were going to replace a transom or fix a hull (of a wood boat)
I also wouldn't use carpet, especially for a fishing boat I would use this flooring instead. I have it in my boat. the water just rolls off, and easy to clean (fish blood)

https://garysupholstery.com/ntomarfloor.html

 

[tashasdaddy]

Re: Is a Treated Deck ok?

the new chenicals in treated wood will eat almost any fastener, even galvinized, and stainless. treated is no better for your project than exterior, treated is treated to stop insects not rot. if left wet marine rots also, that what there are so many transoms, floors, and stringer replaced.

 

[Kevin70]

Re: Is a Treated Deck ok?

I would encapsulate the deck with fiberglass and 1.5 oz. mat. The mat will give you a somewhat non-skid surface and you could paint it with a marine topside paint or carpet it.

 

[flashback]

Re: Is a Treated Deck ok?

Do like kevin says and then roll some gelcoat on it with a 3/8 inch nap roller cover. I will give you a great non skid and look pretty nice also....

 

[andy6374]

Re: Is a Treated Deck ok?

Or add some cabosil to the gelcoat and mix it to a ketchup like consistency and spread that over the deck. The cabosil mixed with the gelcoat will provide a great non-skid.

 

[Terry Olson]

Re: Is a Treated Deck ok?

Treated material is designed for direct contact with the soil. It's not the soil that presents the problem, but the fact that it holds moisture in direct contact with the panel for extended periods of time. From this I make a layman's conclusion (maybe falsely but it makes sense to me) that treated wood is in fact designed to deal with prolonged contact with moisture. Other exterior panels are only designed for limited and occasional contact with moisture, usually only encountered in the construction process. There is a difference if you ask me - but I'm certainly no expert.

If I'm wrong in using green treated I'm in good company judging by the posts on the subject.

 

[JB]

Re: Is a Treated Deck ok?

I used 3/4" CDX to redeck and replace casting decks on a Tracker V17 once.

I would never do that to a quality boat that I intended to keep.

 

[andy6374]

Re: Is a Treated Deck ok?

The main problem with pressure treated ply is that resin doesn't adhere well (mechanically nor chemically).

A piece of AC fir (exterior) or AB fir (marine grade ply) soaked with resin and encaspulated with a couple layers of glass is very resistant to moisture.

 

[Terry Olson]

Re: Is a Treated Deck ok?

I'm fine with Andy's suggestion but the first screw you run into the material results in it's not being encapsulated anymore. There have been a few interesting threads on this issue over on the glen-l website. Most believe that encapsulating a piece of wood before it's installed with screws or other piercing mechanical fasteners is a problem because moisture can and will penetrate at the fastener but has no way to get out.

Some of the old salts over there who build strictly with wood have been at it for decades so they their teacher has been years of experience. That doesn't mean they're right, but they'd know better than I would.

Even so, compromised encapsulation is probably better than untreated wood in a boat.

 

[andy6374]

Re: Is a Treated Deck ok?

When using screws you have two options:

1. The best, most anal way.
- Oversize drill the hole first. Then fill the oversized hole with epoxy. Once cured then put in the screw and the screw will be touching nothing but resin so any water that gets in won't hit the wood core.

2. The way most people go about it.
-Just put a bead of lifecaulk or 3M 101 or 4200 (not 5200 !!!) in with the screw to seal it up.

But IMHO I would encapsulate the wood.

 

[andy6374]

Re: Is a Treated Deck ok?

Or you can use a complete composite core for your deck, like NIDA core, and forget about rot issues all together.

 

[BillP]

Re: Is a Treated Deck ok?

My take on this is...There is unfounded bias against pt wood. Anyone wanting to use it should do some homework. The truth between fact and fiction is easy to find.

PT ply (Greenwood Products brand) has been used in production boats for decades. Resin sticks to it and it doesn't rot when wet. Their process is just like Homedepot pt wood...except Greenwood dries theirs before it leaves the factory.

If fastener corrosion was such an issue with the latest pt process we wouldn't be seeing it approved for life threatening structual applications in building construction. If 1000s of architects design pt applications and 1000s of PEs (Professional Engineers) seal those plans you can bet fastener corrosion is a minor issue...which is handled by using the correctly specified galv or ss fasteners.

Last but not least, I put my money where my mouth is and rebuilt a 17' Cobia using pt stringers, floor and transom. That was approx 5 yrs ago and it still holds like the day it was put down. It gets used often and beat hard. I also used the pt ply scraps placed directly on the ground under the trailer wheels and tongue...so far no rot, delamination or bugs on them from direct exposure either. Maybe the situation will be different in another 20 yrs but I doubt it...at 80 yrs old I won't care either (grin).

 

[seven up]

Re: Is a Treated Deck ok?

whatever

i have never heard of or observed off-the-shelf pressure treated plywood used in production boat building fastened with stainless and encapsulated.

stainless steel cannot be encapsulated and will fail without oxygen.

there's enough bad advice to go around without including thousands of architects and professional engineers as imaginary proof

 

[BillP]

Re: Is a Treated Deck ok?

whatever

i have never heard of or observed off-the-shelf pressure treated plywood used in production boat building fastened with stainless and encapsulated.

stainless steel cannot be encapsulated and will fail without oxygen.

there's enough bad advice to go around without including thousands of architects and professional engineers as imaginary proof

Really? I don't listen to hearsay without investigating credible sources first. I don't guess before posting either. But since you mention "bad advice" and "imagination"...Post the source you use for the statement "stainless steel cannot be encapsulated and will fail without oxygen".

Regardless, the statement about SS doesn't follow past or current industry standards...Ever heard of ASME? 302 & 304 SS pipe/tube has been speced and used for the last 40+ yrs to deliver GN2...that is gaseous nitrogen...which means not enough oxygen or moisture present to measure. Many parts in process gas delivery systems are sealed from air by GN2...none of them fail. Even the Space Shuttle uses SS on the exterior in the motors...all you have to do is look up into the nozzle.