floor chassis undercarriage bed frame screw hole punctures

[jonathanwesc]

My 2005 Interstate Twin has holes in the floor.
These holes were caused by the twin bed frame's sheet metal screws penetrating the floor all the way through the the floor vinyl, wood underlayment, and metal chassis undercarriage.
The screws rusted out leaving holes. The holes allowed water under the vinyl flooring. That caused the wood to rot out. Any ideas on how to plug, fill, or make leakproof the holes?

I removed 4 square inches of flooring, down to the hole penetration through the metal chassis under carriage. Now I need to make that hole water tight so no more water gets inside the motorhome.

[InterBlog]

Could post a couple of pictures?

And also a bit more context. How did you discover this? Did you find it because of visible damage to the floor, or, I could imagine the bed frames potentially beginning to feel loose because their attachment points were weakening due to the corrosion (a scenario that deserves more contemplation in terms that extend beyond remediating the floor damage, given that those beds contain two seat belts apiece).

I think I understand what you're describing - I just want to be sure. This probably goes back to the issue observed previously on other threads - that Airstream did not use hardware and fittings intended for exterior applications, when attaching appurtenances to the chassis or the body of the van. If one crawls under one's T1N chassis and looks upward at the underside, one can see an assortment of corroding hardware, not just the hardware for the couch (e.g., the hardware to attach the subfloor itself). Sooner or later, any T1N Interstate that gets sufficiently old is going to experience some measure of what you describe, if I'm understanding correctly.

On the holes themselves, my first instinct would be:

(1) Overdrill the holes to expose fresh bare metal.
(2) Dab a bit of phosphating compound onto the bare metal to react it out.
(3) Coat the exposed areas with a good metal coating such as Rustoleum or perhaps POR-15.
(4) Once the coating is dry, seal the entire mess with a really stiff and durable caulk such as Sikaflex 221. Work from both the top and the bottom to ensure it's thorough.

If this happened to the extent that it has with your couch attachment points, I'm betting that you've got additional issues under your chassis. I have a couple of blog posts that might interest you. This one describes how I rehabbed the supports for our 2007 Interstate's ground effects (running boards) - I suspect your rig was constructed similarly. This other one talks about how we re-tapped screw holes to better secure the running boards to the chassis.

Please let us know how it proceeds.