Sub-Floor with Belly Pan and Shell On

[Bauxter]

I am going to take the non-marine plywood approach, as well. I have been seeing BCX mentioned in several different forums, and may go that route. Marine sounds awesome, but when the better-half reminded me of budget realities, I decided to use an alternative....like you, I will be sealing, and re-sealing. I don't think that I would consider pressure treated, as I have never really liked that product.

[Llano]

Pressure treated worried me because of the fumes. I've built one too many decks and know how nasty that stuff is.

I want to cover the wheel wells because I plan to incorporate them into the storage I'm building. I hadn't thought of insulation but that's a great idea. One frame built today and the other easily knocked out this week. Even found perfect salvaged lumber at a neighbor's kitchen remodel!

[Llano]

Wheel well covers complete. Now, about those walls...

[1bbboomer]

You should have no concerns with your floor.
If you do a little research you will find marine and exterior ply use the same glue. The difference is in the quality of the plies themselves.
In order for it to be "marine grade" it has to meet a higher standard for voids and patches on the veneer used to make the plywood and typically the exterior plies look nicer.
None of the differences matter for use as sub-floor and do not warrant the considerable cost difference IMHO.

[Wabbiteer]

I found marine (supposed) quality plywood to be gorgeous to look at and work with - but when it came time to screw it down to the frame those eight void-free layers had as much body to them as wet paper towels - many screws buried themselves under the top ply before any real resistance was felt, I was unable to have all the fasteners draw down to anywhere near the same torque.

If I had it to do again I would look for a scaffold-grade OSHA registered plywood, and failing to find that or similar visit the real lumberyards & construction suppliers in this region and have them consult the 'books' to get the facts on composition trade-offs...

Pressure treated is corrosive and kills metal except fasteners designed for it.

[BWH-Utah]

What did you use to "seal" the plywood with?
I have long been a fan of a 50/50 mixture of Cuprinol and Boiled Linseed Oil.
Seems like if you are going with the original glue down 1ft by 1ft floor tiles
the off-gassing of the glue would be as big a concern as the sealant/preservative.
Plus, once the tiles are glued down they will certainly minimize off-gassing migrating
into the trailer.
Any opinions on this approach?
BWH

[Wabbiteer]

Cuprinolgets its name from "Copper in Oil" - copper and aluminum, copper and steel do not mix. I agree your 50/50 mix is easy working and long lasting but has no place in a forever inhabited installation constructed of pre-aged and completely consumable metals...

[Llano]

I painted thick coats of exterior polyurethane on both sides and the edges of the boards previous to installation. Off-gassing has been an issue but hopefully not an enduring one. At least it overpowers the previous funky smell...

[fooddudejeff]

The new sub floor looks great.. Did you just cut old floor as close as you could to base of wall and cut to fit new floor.

[Llano]

Old floor had graciously rotted apart over the years, so it literally crumbled away. The tricky part of the shell-on sub-floor (I learned the hard way) is ensuring that you cut your plywood long enough to get under your floor channels on both sides - yet short enough to actually fit. Think flat metal tools, gentle wedging, and not-so-gentle profanity spewing. Scroll up in this thread, I got some GREAT advice from the masters and mistresses!

Tropical Storm Hermine has "informed" me of a couple small leaks...

[BWH-Utah]

Originally Posted by Wabbiteer

Cuprinolgets its name from "Copper in Oil" - copper and aluminum, copper and steel do not mix. I agree your 50/50 mix is easy working and long lasting but has no place in a forever inhabited installation constructed of pre-aged and completely consumable metals...

True Cuprinol is named for its original formulation copper-in-oil. They NO LONGER make it that way. It is now made with "propiconazole fungicide" in most formulations and other specialty fungicides for specific applications. Many interior "bathroom" latex paints and most exterior latex paint also has chemical fungicides mixed in. It seems like the added fungicide would help in preserving the wood. After-all this is not a job most people want to do more than once.
BWH

[Wabbiteer]

The US Cuprinol site is under construction and the parent company Sherwin-Williams is no help - they have changed their formulations so many times the Internet is littered with out-dated MSDS information. The United Kingdom Company has their product info everywhere but it doesn't apply to US markets. Best that I can tell...

Cuprinol Clear Wood Preservative has (had?) a Zinc Salt.
Cuprinol No. 10 Green Wood Preservative has a Copper Salt.
Cuprinol Deck and Siding Preservative (discontinued?) has /had 3-iodo-2-propynyl butyl carbamate in it and is for exterior use only - (very weak cholinesterase inhibitor)

I can't find which blend uses propiconazole and flurox in the USA - the former is widely used on foodstuff grains (in minute quantities) while the later kills wood boring insects of concern in the United Kingdom. The only long-term hazard warning for treated areas is chance of allergic reactions.

Yes - it'd be nice to have plywood with that in every layer but a quick surface coating isn't going to stop dry-rot when moisture has wicked deep enough to allow glue failures. If there is any silicones or oils there is the chance present or future paint will fail to bond.

Its a slippery slope of what to chemically guard against for sure.