Alternate skins ....

[KCStudly]

100% sealed 10% of the time.

My neighbor up the street at "the garbage house" has a small 5 x 10 or 12 CT and a large class C RV, neither are that old, both are stored with cheap plastic tarps strapped to their roofs. What does that tell you? Tells me that they are both leakers.

[TheOtherSean]

Even if they start out 100% sealed, they will eventually leak. I've done the Airstream factory tour once and watched them do the waterproof testing, so at least they take it semi-seriously during manufacturing, but looking at the used trailer ads you'll see they're often having leak problems after 5-15 years out - and that's considered a premium trailer. Just about every unrestored vintage trailer that wasn't stored inside was subject to some level of leaking and water damage. The only real questions were where the water came in and how widespread the damage was.

[aggie79]

"(food for mold, etc when wet) “ .... Hence the need for the waterproofing .... OK ???

Okay!!! Waterproofing is certainly important.
Observation: Almost every wood-framed factory trailer leaving the showroom is 100% waterproof. Many of them have rotted through after a few short years.
What would belt and suspenders look like?
- Keep the water out (protects the contents and the structure of the trailer)
- Design and build so the trailer can dry quickly when water does get in (no materials or assemblies that trap liquid or vaporous water)
- Avoid materials that fail when wet.

But, that's admittedly an ideal approach. In real life, compromises are usually required if we want to make progress.

Mark

If I can add another point to your list, I would say "use interior finishes that do not seal in any water or vapor intrusion".

Even in Along the southern coast - assuming termites or hurricanes didn't finish them off - historical wood-framed homes with wood siding have lasted 100 years. It was only till "tight" homes were built that problems started arriving. Even water-logged boats last for centuries.

[GPW]

Well that’s the problem isn’t it .... Water and Trailers do not mix ... And water gets in through the smallest places , and is carried through unsealed wood by capillary action .... Two extremely Bad characteristics ... Which gives rise to the notion that ALL the materials should be completely waterproofed from the beginning ...

As with anything , if you really like it , keep it in the Garage , as Nature tends to “wear” on everything ... eventually ...
Foamies do fine outside , but still get dirty , grow mold and other things that only decreases the longevity of the paint ,and requires cleaning ... Stored inside , you’d only paint it when you got tired of the color ...


Aggie , so true ... it’s only trouble when the water can’t get out quickly ...

[vigilant1]

"(food for mold, etc when wet) “ .... Hence the need for the waterproofing .... OK ???

Okay!!! Waterproofing is certainly important.
Observation: Almost every wood-framed factory trailer leaving the showroom is 100% waterproof. Many of them have rotted through after a few short years.
What would belt and suspenders look like?
- Keep the water out (protects the contents and the structure of the trailer)
- Design and build so the trailer can dry quickly when water does get in (no materials or assemblies that trap liquid or vaporous water)
- Avoid materials that fail when wet.

But, that's admittedly an ideal approach. In real life, compromises are usually required if we want to make progress.

Mark

If I can add another point to your list, I would say "use interior finishes that do not seal in any water or vapor intrusion".

Even in Along the southern coast - assuming termites or hurricanes didn't finish them off - historical wood-framed homes with wood siding have lasted 100 years. It was only till "tight" homes were built that problems started arriving. Even water-logged boats last for centuries.

Aggie, I agree with your expansion on my second point. If the wall assembly can't dry to the outside, then it needs to be able to dry to the inside (and there needs to be a vent open or another way for the interior air to exchange with the outside).
I suppose If a trailer was going to be heated and cooled for most of its life (like a house typically is), then we'd need to concern ourselves with which way the water vapor pressure was going most of the time and we'd put the most restrictive vapor barrier on the correct side (usually toward the side that is expected to be warm the most. For those of us in "heating climates" that means on the inside of the wall assembly, so we use batts of insulation with a vapor barrier toward the inside of the home)). But if a trailer isn't going to be occupied all the time, it's probably sufficient that the water that gets into the assembly (through leaks, through condensation of water vapor that travels through gaps either way, or through transpiration of water vapor directly through the materials) has a way to get out, and it probably doesn't matter if it goes in or out.

So, a lead-up to a science project from this newby: Has anyone figured out the "perm rating" of the unique materials often used in TnTTT construction? Is it of interest? That would give us a good idea if drying can be expected to occur. If that's not known, I'll start a new thread to get some solicitations before I go any farther with a homebrew experiment. Ideas for testing would include:
--- 1) Thick uncorrugated cardboard (aka chipboard) treated with "the mix" (75% mineral spirits/25% polyurethane sealer)
--- 2) Same as above, but with fabric and TB II on the surface
--- 3) 3/4" plywood treated with "the mix" (as used in floors, etc)
--- 4) Fabric with TB II (not attached to anything)
--- 5) 1" of XPS with FG and epoxy

Controls (so I can adjust any results I get with published numbers for known standard materials that have published perm ratings)
--- 1" of XPS foam
--- 3/8" drywall
--- Aluminum foil (zero perm)

I've got a stake in this, as I am thinking about building with a painted FG/epoxy skin (outside), 2" XPS foam, FRP (fiberglass reinforced panels) on the inside. While that has some good points, it might not dry well when water does get inside.

Mark

[GPW]

Actually with a Foamie , we don’t expect anything to get wet , or be affected if it does ... It’s NOT an ordinary TTT building material ... Actually all of those materials have been extensively tested , which is how we arrived at where we are now ... It’s only the skeptics that need to prove this to themselves all over again ... (And those who have not bothered to read the Big thread ... )

[aggie79]

GPW,

I remember buying some 12" squares of kraft-faced foam board a few years back to experiment with. I think it was 3/16" or 1/4" thick. The kraft paper faces were "raw" - not coated. I was going to laminate a few layers together to see it could be used as lightweight panels for walls, cabinets, etc. Well..life intervened and I never got to the project.

I need to see if they are still around somewhere. If I can round them up I'll try the mix on one to see how the kraft paper reacts. I'm not sure what type of foam the middle is though. Hopefully it won't dissolve with the solvents.


Take care,
Tom

[GPW]

Tom, Thanks !!! We can always use more valid testing ....

[aggie79]

GPW,

I remember buying some 12" squares of kraft-faced foam board a few years back to experiment with. I think it was 3/16" or 1/4" thick. The kraft paper faces were "raw" - not coated. I was going to laminate a few layers together to see it could be used as lightweight panels for walls, cabinets, etc. Well..life intervened and I never got to the project.

I need to see if they are still around somewhere. If I can round them up I'll try the mix on one to see how the kraft paper reacts. I'm not sure what type of foam the middle is though. Hopefully it won't dissolve with the solvents.

Materials Testing - Take #2

Well, I couldn't find the kraft-faced foam board. On top of that the missus asked me to finish the retaining wall project I started 2 months ago. So...I am going to have to delay my testing. When I get around to it, I going to use some of roll of uncoated kraft paper that I have and make some test squares. I will make a series of test squares with 1, 2, and 3 layers of paper over the foam. The first paper layer will be bonded with either TB II or Gripper. I'll then seal the first layer with the mix. For the multiple layer squares, I think I'm going to try to use the mix as the adhesive. We'll see how things go.

[KCStudly]

I predict that the mix will be too thin to adhere paper to foam well. It does not have the bridging capability needed to fill small voids.