Quote:
Originally Posted by jonathanwesc
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I'm considering paying someone else to replace the floor underlay in a 2005 Interstate Twin Rear Lounge / Mid-bath. ...
Not sure what percentage of the floor is rotten. My estimate is: 90% of the driver's side; 50% of the central aisle; and 65% of the passenger side. .... The floor underlay I removed looked like a mix of potting soil with varying degrees of wood board fiber and solid wood. I've not found any significant places where the moisture is still getting inside. .....
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Bold emphasis mine above. Partial cross-post of an update here.
I lost track of this OP, but I never forgot the issue itself. My husband and I may have inadvertently just solved
part of the riddle of where and how significant water can penetrate into a T1N's plywood subfloor.
As explained on another thread (
here), I pulled up the table leg receivers in the rear of our Interstate. We recently installed a Lagun table with two sets of mounting hardware, front and back of the van (
here), and so we no longer need those OEM receiver cups that Airstream inserted into the floor, and which extend all the way through the chassis.
Furthermore, I wanted to add carpet tiles, and the original receivers stick up too far above the plane of the floor to do this. So out they came, and I've sealed the holes temporarily with two thin, flat sheet metal caps that I fabricated yesterday, as shown in the photo below (LB_3 finds these to be inelegant, but they are temporary, and carpet tiles will go over the top of them even in the short term, so they won't be visible).
It wasn't until we situated these replacement caps that we could see the degree to which the plywood subfloor is swollen in the vicinity of these penetrations. Airstream did not properly seal the holes that they cut in this location, which allowed water penetration from below. Our situation is not nearly as severe as that described by the OP, but I'm glad that I located it when I did, because now I can seal off the area and prevent the condition from worsening.
Now that I know more about a likely water penetration pathway, I can formulate an hypothesis as to why the OP's rot condition was so severe (as reported by him).
I speculate that the described pattern of damage was caused by termites which accessed the subfloor through the table leg penetrations. All that would be needed for that to happen is for them to build a mud tube up to the chassis penetration. Anyone who has ever had termites in their house knows how incredibly adaptive they can be - they can "smell" and locate damp wood across long distances. They build their own transportation tubes many feet into the air in order to access desirable wood.
Originally I was accepting the hypothesis that the OP's subfloor got wet because of water penetration via the ROOF (Fantastic and/or other penetrations). If that were solely the case, there'd still be no means of access for termites. But wetting from the ground up? That's another scenario entirely.
How could termites (and/or other wood-destroying insects such as carpenter ants) establish themselves in a motor vehicle, you might wonder? Even if they get in, the thing is on the move, so how would they get established and remain viable?
= Very easy for them if the rig is left parked in one spot for months at a time, which many owners tend to do.
This is just my speculation, but there it is. The OP's description of extensive but patchy rot and "coffee grounds" is very consistent with wood-destroying insects.
Meanwhile, I've got a floor to patch and seal, PROPERLY this time (as I stick yet another needle in my Airstream voodoo doll).
Here's one of my thin, flat metal caps. We might get SNOW in Houston in the next 24 hours, so I had to fabricate and install these lickety-split so that rodents would not make these two holes into their personal Stairway to Heaven. The next cold front is going to have rodents activating their predictable migration into cozier areas of all kinds. That happens to us in the south. Rodents tend to remain outdoors until the weather becomes inhospitable. Then they make a major run for it.