Board floors , not plywood ...

[GPW]

All along in our many discussions of materials to use for floors .. Plywood always comes out the winner , and then the loser ... Easy to cut and fit as a sheet , But weakens with any water intrusion (that spreads) ... so we slobber it with the Mix , smear black nasty stuff on the bottom , paint the top , and hope for the best . But while all this is going on , my all steel cargo trailer (homemade) , has a floor made from boards ... just plain boards ... untreated on the bottom , no BNS, and some linoleum thrown over the top ... and it’s in Great shape although being much older than anything I have ...
We notice , the Old timers used board floors too ... likely economic, but then again , many of those trailers lasted a long time ... and some didn’t ...
Also with a board floor you could build up the edges to provide more foam gluing area , or even run the foam below the floor as a “skirt" (or drip edge) ... And you could even use stronger species of wood for the high stress areas , and lighter wood for the rest ...
Always trying to think of ways to make a Foamie Better ... My next trailer might have a board floor ...

[GPW]

And just another thought .... Board floors would enable you to assemble the sides with the floor frame end rails attached , then covered underneath easily on a flat table ... then just screwed to the floor frame like all the other boards ... You could theoretically cover the side and floor board underneath with a reinforcing strip , and once assembled just run the side canvas down to the bottom and trim it off flush ... good not having to get on your back underneath the trailer to wrap the floor to wall join.

[Ned B]

GPW hate to say it, but look at how many joints there are there just in that picture. As we all know joint = water intrusion point, plywood sheeting may have its downsides, but minimizing joints isn't one of them. Plywood is also dimensionally stable. If you butt those boards up side to side like that every one of them will expand & shrink with the seasons. Part of the problem you mention with ply is that it delaminates. Let's face it, how many of us are buying from the big box stores? Their ply is sourced from the absolute cheapest sources, they buy in bulk and just like traditional RV manufacturers they cut to the bottom line wherever they can. There are better rated marine grade plywoods available, they cost more, but will be much better at surviving water issues due to better glues. Cost difference between them... Perhaps 50% more, but if you have to replace the lesser grade down the road thats 100% higher or more!
Big rigs have wood floors, usually white oak 8/4 laid up on edge, screwed together and with steel support beams. They're also treated with the Gunk to help keep out water.

[Tomterrific]

Shanty boats (old time house boats) were built using found and bought boards. The sides were made upside down and boards were nailed across for the bottom of the boat. Between each board was a cord drenched in white lead to keep out water. If these old shanty boats could float in the Mississippi I see no reason a board floor could not be waterproof with a bead of caulk between each board. I used plywood for my floor 'cause it was easy and quick to build.

Tom

[GPW]

Naaa!!! Ned ... What you say is True !!! Really good plywood does not come from the box stores and is considerably more expensive than what most of us are willing to pay up front ( the budget)... What we found with previous trailers and friends trailers , is that water coming up is not the problem .... It’s always the inability to drain the water from above that’s the main problem ... Commercial trailers have “membranes” (cheap vinyl) which hold water like a great saggy balloon under the trailer ( seen that 3 times now ) , naturally rotting the entire floor ...


Tom .... There are so many examples of board floors in the past that actually worked ... as you’ve so noted !!!

Here’s my favorite .... board floor ... http://tnttt.com/VintagePlans/connestogawagon.pdf

[tony.latham]

You are going to get at least 3/4" of lateral movement on a 5' wide board floor. It'll probably work if you allow for that movement in mind (both expansion and contraction).

Me? I seal all of my plywood with Raka's thin epoxy. But I don't live in the jungle.

Here's a interesting experiment from CPES on treating AC plywood with their very thin product:

http://www.rotdoctor.com/test/plywood/plywood.html

Tony

[GPW]

The only thing is , Big Mike used that on a trailer and it delaminated ... We’re unsure of the circumstances ...and really unsure of that product as being any better than anything else ... So much HYPE today, hard to believe any advertising babble ... Everything must be tested in Foamieland ... And speaking of , the board floor in the All Steel cargo trailer has gotta’ be at least 20+ years old , and still is perfect ... The wood has turned grayish , but is not rotten or damaged in any way ... It can drain and dry quickly and the sun can’t hit it ... and it does live in a jungle .... sorta’ ...

[tony.latham]

The only thing is , Big Mike used that on a trailer and it delaminated ... We’re unsure of the circumstances ...and really unsure of that product as being any better than anything else ... So much HYPE today, hard to believe any advertising babble ... Everything must be tested in Foamieland ... And speaking of , the board floor in the All Steel cargo trailer has gotta’ be at least 20+ years old , and still is perfect ... The wood has turned grayish , but is not rotten or damaged in any way ... It can drain and dry quickly and the sun can’t hit it ... and it does live in a jungle .... sorta’ ...

I looked that thread up. Here's what Mike said:

I started peeling the paint back. The paint was still attached to the outer layer of plywood. So it's definitely the plywood delaminating.

It looks like it got in thru the screw holes... so injecting silicone into the screw hole before putting the screw back in wasn't enough. Maybe I should have used superglue? Maybe some CPES injected into the screw holes? Any thoughts?

Mike...

And farther along he says:

So I think, the moral of the story is, don't use birch plywood for exterior skins.

I still think that using a good exterior grade plywood and sealing it well will work fine––at least up here in the high mountain desert where I live! I guarantee there's no rot going on here lately, It hasn't gotten above 20ºF since Christmas. Sheeeeeeesh. When's the opening day of camping season, anywho?

Cheers,

Tony

[Tomterrific]

Boats are made of plywood. It's not only marine plywood, exterior uses the same glue. If anyone uses interior grade plywood on an exterior project they have only themselves yo blame. In another thread I mentioned that sometimes looks must be sacrificed for function.

Tom in cbus

[angib]

Separate boards have no shear strength (one can slide forwards/backwards relative to the next one) so the torsional stiffness of the body will be reduced. Is it significant? Dunno. Would I use it? No.

Tongue and grooved boards with glued joints would eliminate this and any leakage.

[GPW]

Tony , Thanks for looking that up !!! Bad ply ... Makes sense eh ?

Tom , Boats we owned made of plywood all developed Rot after a while ... even the old Chris Craft ... Now boats here are made of Fiberglass or Metal (Aluminum)

Angib ... separate boards glued and nailed ( or screwed or bolted ) to underlying frame or contained in a metal angle iron frame ... I cannot argue , my only proof of concept is the trailer sitting outside ...

Now then , anybody have a better idea ... ? Terribly expensive ply is off the menu as it just doesn’t suit the Foamie Thrifty concept ...

[dogscats]

A wood boat will dry out and get gaps. You could do a lap seam are board and battens that will get heave.

[KennethW]

GPW My 2" foam floor will not delaminated or rot. with the canvas bottom and FRP top it is strong enough and very light.

bottom up
This was just fitting. The wall sat on top of the floor with frp skin extending down past the floor. glued down with polyurethane caulk.

[GuitarPhotog]

Just another data point for plywood.

My 1947 teardrop has a 1" plywood floor, a single 4ft X 10ft piece. It is painted on the top, interior side and was left bare on the bottom, exterior side.

68 years of exposure to the elements, including the 11,000+ miles I've towed it in all kinds of weather, have not caused the plywood to delaminate. You have to choose the correct kind of plywood to begin with.

Not all plywood is bad, just the cheap stuff.

<Chas>

[GPW]

Good points for both Plywood and boards , or even foam ... Guess it’s up to the builder to choose ...

FYI, I’m only trying to promote different ideas here , so don’t get mad at me if you don’t agree... Simply post your views for consideration too ...