Splicing Sub Floor on Frame Rail Acceptable?

[Venturewest]

I have a 1968 Tradewind with some perimeter floor rot, forward of the wheel wells on each side. My plan was to cut the section out and make my splice over the middle of the main frame rails. The old plywood and the the new plywood would meet on the center of the rails. I would use self tapping screws and possible construction adhesive to attach the floor to the frame rails. The sections I will be replacing will be approximately 4' long x 14" wide (whatever the distance is from the c channel to the center of the frame rails.)

Does this sound like it would be an acceptable way to make the splice?

Also, I want to make sure I am using the right term for the frame rail. I am calling the rail the main beam that runs from the front to the back of the trailer.

I really appreciate your help. I have read countless threads on sub floor replacement and I haven't found anything that addresses this specific method.

[rugjenkins]

It would be better to extend your cut closer to the center of the trailer (best). Or extend past the frame rails 3 to 4 inches (good). Then cut a splice patch underneath both old and new, glued and screwed.

[Venturewest]

Originally Posted by rugjenkins

It would be better to extend your cut closer to the center of the trailer (best). Or extend past the frame rails 3 to 4 inches (good). Then cut a splice patch underneath both old and new, glued and screwed.

Thanks Matt. Is the reason for not splicing on the center of the frame rail because the screws would be so close to the edge of the plywood and could be in danger of pulling out? I can see how that would be a problem as the frame flexes.

[rugjenkins]

The less amount of holes the better. These frames are thin. If you splice wood to wood with a backer splice plate on the bottom you are essentially making your floor solid again. Besides it's easier to glue and screw wood together than to metal[emoji1]

[Venturewest]

Thanks so much for your quick reply. That makes perfect sense and I will proceed with the repair.

[rugjenkins]

[emoji106][emoji1]

[mmcgue]

I agree with Rugjenkins. Don’t splice on top of the thin frame. A glued wood-to-wood joint should be as strong as the plywood itself. With a wood to metal joint you are counting on the screw to frame joint which would not be as strong (nor was the Airstream designed to be assembled that way). From my experience, where there is wood damage there is often frame rusting as well, making an even worse situation for using the frame as a fastener.
Locate the joint where you can gain access from underneath. Paint the frame with POR15, and use a plywood “splice” board underneath the joint at least four inches in width, surfaced glued with a good “carpenter’s” glue and screwed to the existing floor and the patched floor on both sides of the joint. Finally, seal entire joint from bottom and top with a good two part epoxy (like a table top finish) applied to both sides of the joint with a throw away brush. You’ll be good to “go”!

[harryk]

I made several splices on top center of the frame rail and some on top center of the side to side rails. I did not screw the floor to the frame. In my case, the weight of the twin beds and screwing the beds to the floor was sufficient, and its been fine for years.

[TouringDan]

I agree with the repair comments by Rugjenkins.

I don’t agree that just because you have floor wood rot that you have frame damage. I repaired lots of rotted wood floor in my 66 Tradewind that had no frame damage. This can be seen in my thread “Dan’s 66 Tradewind Improvements”. I also believe that you can repair the floor from above. You don’t need to have access from below.

Dan

[Venturewest]

Originally Posted by TouringDan

I agree with the repair comments by Rugjenkins.

I don’t agree that just because you have floor wood rot that you have frame damage. I repaired lots of rotted wood floor in my 66 Tradewind that had no frame damage. This can be seen in my thread “Dan’s 66 Tradewind Improvements”. I also believe that you can repair the floor from above. You don’t need to have access from below.

Dan

Hah. Here is some evidence that your statement is absolutely true. I cut out one big section of plywood I am replacing and here is the frame I found. It doesn't even have surface rust. No POR 15 needed here. I really like the spray foam that Airstream Used. At least in this case it did a great job protecting the from from damage. It really makes the floor feel solid as well. It is going to be a pain undercutting the foam to make a good splice though!

[ALUMINUMINUM]

1968 was the only year that had foam floor insulation. At that time Avion and Silver Streak were already using foam insulation. I wonder why AS went back to fiberglass blanket. Perhaps Airstream's new owner Beatrice Foods(aquired Airstream in late 1967 during 1968 model production) cut costs, or the factory floor laborers objected to the new process?? Perhaps an Airstream Historian could say.


The foam seems to protect the steel. I removed a little bit from the 1968GT frame and sub-floor and the surfaces were better preserved than where it wasn't sprayed on. It was all shiny like new beneath the foam. The plywood sub-floor was un-oxidized. The foam is closed cell. I submerged a chunk in my frog pond for a few days and it bobbed up dry as cork.


The foam doesn't hold moisture like fiberglass, so it appears that as long as water doesn't find a path between the foam and what it's adhered to, it may be a superior method to insulate. My 50yo belly-pan area was in mint condition. There is no evidence of foam deterioration or dusting, no teeth marks or inhabitants. I repaired some sub-floor, but No frame repair required.



Congratulations,I think that the '68 Trade Wind might be the finest Airstream ever built.

[TouringDan]

Originally Posted by ALUMINUMINUM

1968 was the only year that had foam floor insulation. At that time Avion and Silver Streak were already using foam insulation. I wonder why AS went back to fiberglass blanket. Perhaps Airstream's new owner Beatrice Foods(aquired Airstream in late 1967 during 1968 model production) cut costs, or the factory floor laborers objected to the new process?? Perhaps an Airstream Historian could say.


The foam seems to protect the steel. I removed a little bit from the 1968GT frame and sub-floor and the surfaces were better preserved than where it wasn't sprayed on. It was all shiny like new beneath the foam. The plywood sub-floor was un-oxidized. The foam is closed cell. I submerged a chunk in my frog pond for a few days and it bobbed up dry as cork.


The foam doesn't hold moisture like fiberglass, so it appears that as long as water doesn't find a path between the foam and what it's adhered to, it may be a superior method to insulate. My 50yo belly-pan area was in mint condition. There is no evidence of foam deterioration or dusting, no teeth marks or inhabitants. I repaired some sub-floor, but No frame repair required.



Congratulations,I think that the '68 Trade Wind might be the finest Airstream ever built.

I did not know that. Thanks for the education. I agree that the ‘68 Tradewind might be the finest Airstream ever built.

From your photo, it looks like there was just a thin layer of foam, like maybe 1”, then maybe 4” of air between the foam and the belly pan.

Did you have any floor rot by the bumper trunk?

Dan

[Venturewest]

Originally Posted by TouringDan

I did not know that. Thanks for the education. I agree that the ‘68 Tradewind might be the finest Airstream ever built.

From your photo, it looks like there was just a thin layer of foam, like maybe 1”, then maybe 4” of air between the foam and the belly pan.

Did you have any floor rot by the bumper trunk?

Dan

I do not have any rear floor rot. However, any of the exposed parts of my frame are rusty. The angle support for the black water tank is completely rusted out and broken off. I will be cleaning up the exposed areas and painting them. I am going to start a thread today on my restoration.

[Venturewest]

Originally Posted by ALUMINUMINUM

1968 was the only year that had foam floor insulation. At that time Avion and Silver Streak were already using foam insulation. I wonder why AS went back to fiberglass blanket. Perhaps Airstream's new owner Beatrice Foods(aquired Airstream in late 1967 during 1968 model production) cut costs, or the factory floor laborers objected to the new process?? Perhaps an Airstream Historian could say.


The foam seems to protect the steel. I removed a little bit from the 1968GT frame and sub-floor and the surfaces were better preserved than where it wasn't sprayed on. It was all shiny like new beneath the foam. The plywood sub-floor was un-oxidized. The foam is closed cell. I submerged a chunk in my frog pond for a few days and it bobbed up dry as cork.


The foam doesn't hold moisture like fiberglass, so it appears that as long as water doesn't find a path between the foam and what it's adhered to, it may be a superior method to insulate. My 50yo belly-pan area was in mint condition. There is no evidence of foam deterioration or dusting, no teeth marks or inhabitants. I repaired some sub-floor, but No frame repair required.



Congratulations,I think that the '68 Trade Wind might be the finest Airstream ever built.

Thanks a lot. I am very excited about restoring this trailer. I am going to start a new thread later today showing all the photos of the original interior. It really is a beautiful trailer. I actually had a '67 Land Yacht Tradewind for a brief period, and it also had foam. Maybe it was a late model.

[ALUMINUMINUM]

Did you have any floor rot by the bumper trunk?


YES! A very long and arduous repair task exacerbated by my stubbornness to do it without removing any bath plastic or interior skin. There's no foam in the black tank bay, but it is completely foamed outside the frame rails in the last outrigger/rear tapered belly wrap area.


I think the “Bumper Box” came into full-play about 1964 with the “Airline” bath that lasted thru 1966*. They needed space to evacuate the new under-floor black tank. Sadly, The designers “lost focus”... In their futile enthusiasm to keep the B-box unnecessarily dry, they created a flashing design that funneled water into the rear sub-floor. I have to believe that there must have been a worker or two that pointed this out to management/design, as anyone who has even only shingled a dog house could clearly see the mistake, but the ignorant, floor-rotting design was denied for decades.


The foam thickness varies quite a bit. I think it may have been specified to be 2” thick, as it mostly is. Some areas are 3” others less.


As the foam years go, I wonder if the start/stop times were influenced by California or Ohio builds. There's not much documentation, but it's rumored that Beatrice Foods(of milk and processed cheese foods fame) was diversifying by purchasing different companies, then cost-cutting them into oblivion.


* Interestingly, the “Airline Bath” was not used in the Globe Trotter during those years, the GT shared the little Caravel's rear wet-bath. The '67/'68 GT got the big trailer's “Penthouse” bath, Which I'll say was the most brilliant rear bath of any year, ever.

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